Where did the universe come from?

We know that at the moment space is expanding and this means that in the past everything was close together, here the Big Bang theory has his origins.

We can see the moment when the universe was very packed together at the period of 1 second after the Big Bang and we can also here the echo of that period.

The problem begins when the universe is even younger then 1 second because the only vision of that period comes from our theories, due to the fact that we can't reproduce that period in a laboratory yet. The drawback of these theories is the fact that we have to use quantum (because of the small objects we have to deal with) and relativity (because of the massive objects that we have to deal with). However, those theories do not work together.


This is the background radiation as we see it










Two conversions of ripples in the radiation that have been converted to the frequencies that we can hear.

 

| la 1:44 PM | 0 comentarii

Modern mysteries of astronomy

In this post I will try to present the 11 mysteries of modern astronomy and in the future I will discuss them individually.

There are the 3 well renowned mysteries:

And the 8 less renowned ones:
  • How did Black Holes get so big?
  • Where are the dwarf galaxies?
  • Sedna's Orbit
  • Lack of Tidal Locking
  • Long Stellar Pulsation
  • Planet Formation
  • Jets
  • Comet Tails

| la 10:01 AM | 0 comentarii

Neptune

Diameter: 49,500 kilometers
Temperature: -200 °C (72 K)
Orbit: Takes 164.8 Earth-years to complete an orbit.
Average Distance:  4,500 million kilometers - 2,794.4 (millions of miles) from Sun
Mass:  17.15 Earth-masses
Moons: 13
Period of Rotation: 17.7 hours

Missions to Neptune:

Voyager 2's closest approach to Neptune occurred on August 25, 1989

Neptune in history:


Galileo was the first to observe Neptune on December 28, 1612 and again on January 27, 1613 but in both occasions, Galileo mistook Neptune for a fixed star. During the period of his first observation in December 1612, Neptune was stationary in the sky because it had just turned retrograde that very day. This apparent backward motion is created when the orbit of the Earth takes it past an outer planet.  In July 2009 University of Melbourne physicist David Jamieson announced new evidence suggesting that Galileo was at least aware that the star he had observed had moved relative to the fixed stars.


In 1821, Alexis Bouvard published astronomical tables of the orbit of Neptune's neighbor planet Uranus. Subsequent observations revealed substantial deviations from the tables, leading Bouvard to hypothesize that an unknown body was perturbing the orbit through gravitational interaction. In 1843, John Couch Adams began work on the orbit of Uranus using the data he had. Via James Challis, he requested from Sir George Airy, the Astronomer Royal, who sent the data in February 1844. Adams continued to work on this in 1845-1846 and produced several different estimates of new planet, but did not respond to a request from Airy about the orbit of Uranus.

In 1845–46, Urbain Le Verrier, independently of Adams, developed his own calculations but also experienced difficulties in stimulating any enthusiasm in his compatriots. In June 1846, upon seeing Le Verrier's first published estimate of the planet's longitude and its similarity to Adams's estimate, Airy persuaded Cambridge Observatory director James Challis to search for the planet. Challis vainly scoured the sky throughout August and September.

Meantime, Le Verrier by letter urged Berlin Observatory astronomer Johann Gottfried Galle to search with the observatory's refractor. Heinrich d'Arrest, a student at the observatory, suggested to Galle that they could compare a recently drawn chart of the sky in the region of Le Verrier's predicted location with the current sky to seek the displacement characteristic of a planet, as opposed to a fixed star. The very evening of the day of receipt of Le Verrier's letter on September 23, 1846, Neptune was discovered within 1° of where Le Verrier had predicted it to be, and about 12° from Adams' prediction. Challis later realized that he had observed the planet twice in August, failing to identify it owing to his casual approach to the work.

In the wake of the discovery, there was much nationalistic rivalry between the French and the British over who had priority and deserved credit for the discovery. Eventually an international consensus emerged that both Le Verrier and Adams jointly deserved credit. Since 1966 Dennis Rawlins has questioned the credibility of Adams's claim to co-discovery and the issue was re-evaluated by historians with the return in 1998 of the "Neptune papers" (historical documents) to the Royal Observatory, Greenwich. After reviewing the documents, they suggest that "Adams does not deserve equal credit with Le Verrier for the discovery of Neptune. That credit belongs only to the person who succeeded both in predicting the planet's place and in convincing astronomers to search for it."

Shortly after its discovery, Neptune was referred to simply as "the planet exterior to Uranus" or as "Le Verrier's planet". The first suggestion for a name came from Galle, who proposed the name Janus. In England, Challis put forward the name Oceanus.

Claiming the right to name his discovery, Le Verrier quickly proposed the name Neptune for this new planet, while falsely stating that this had been officially approved by the French Bureau des Longitudes. In October, he sought to name the planet Le Verrier, after himself, and he had loyal support in this from the observatory director, François Arago. This suggestion met with stiff resistance outside France. French almanacs quickly reintroduced the name Herschel for Uranus, after that planet's discoverer Sir William Herschel, and Leverrier for the new planet.

Struve came out in favour of the name Neptune on December 29, 1846, to the Saint Petersburg Academy of Sciences. Soon Neptune became the internationally accepted name. In Roman mythology, Neptune was the god of the sea, identified with the Greek Poseidon. The demand for a mythological name seemed to be in keeping with the nomenclature of the other planets, all of which, except for Earth, were named for Greek and Roman mythology.

Most languages today, even in countries that have no direct link to Graeco-Roman culture, use some variant of the name "Neptune" for the planet; in Chinese, Japanese and Korean, the planet's name was literally translated as "sea king star" (海王星), since Neptune was the god of the sea.




Neptune internal structure: 


Neptune's internal structure resembles that of Uranus. Its atmosphere forms about 5 to 10 percent of its mass and extends perhaps 10 to 20 percent of the way towards the core, where it reaches pressures of about 10 GPa. Increasing concentrations of methane, ammonia and water are found in the lower regions of the atmosphere.

The mantle reaches temperatures of 2,000 K to 5,000 K. It is equivalent to 10 to 15 Earth masses and is rich in water, ammonia and methane. As is customary in planetary science, this mixture is referred to as icy even though it is a hot, highly dense fluid. This fluid, which has a high electrical conductivity, is sometimes called a water-ammonia ocean. At a depth of 7000 km, the conditions may be such that methane decomposes into diamond crystals that then precipitate toward the core. The mantle may consist of a layer of ionic water where the water molecules break down into a soup of hydrogen and oxygen ions, and deeper down superionic water in which the oxygen crystallises but the hydrogen ions float around freely within the oxygen lattice.

The core of Neptune is composed of iron, nickel and silicates, with an interior model giving a mass about 1.2 times that of the Earth. The pressure at the centre is 7 Mbar (700 GPa), millions of times more than that on the surface of the Earth, and the temperature may be 5,400 K.


Rings of Neptune:




Neptune has a planetary ring system, though one much less substantial than that of Saturn. The rings may consist of ice particles coated with silicates or carbon-based material, which most likely gives them a reddish hue. The three main rings are the narrow Adams Ring, 63000 km from the centre of Neptune, the Le Verrier Ring, at 53000 km, and the broader, fainter Galle Ring, at 42000 km. A faint outward extension to the Le Verrier Ring has been named Lassell; it is bounded at its outer edge by the Arago Ring at 57000 km.

The first of these planetary rings was discovered in 1968 by a team led by Edward Guinan, but it was later thought that this ring might be incomplete. Evidence that the rings might have gaps first arose during a stellar occultation in 1984 when the rings obscured a star on immersion but not on emersion. Images by Voyager 2 in 1989 settled the issue by showing several faint rings. These rings have a clumpy structure, the cause of which is not currently understood but which may be due to the gravitational interaction with small moons in orbit near them.

The outermost ring, Adams, contains five prominent arcs now named Courage, Liberté, Egalité 1, Egalité 2 and Fraternité (Courage, Liberty, Equality and Fraternity). The existence of arcs was difficult to explain because the laws of motion would predict that arcs would spread out into a uniform ring over very short timescales. Astronomers now believe that the arcs are corralled into their current form by the gravitational effects of Galatea, a moon just inward from the ring.

Earth-based observations announced in 2005 appeared to show that Neptune's rings are much more unstable than previously thought. Images taken from the W. M. Keck Observatory in 2002 and 2003 show considerable decay in the rings when compared to images by Voyager 2. In particular, it seems that the Liberté arc might disappear in as little as one century.

| la 6:10 AM | 0 comentarii

Uranus



Diameter: 51,500 km (32,000 miles)
Temperature: -197.15 C (-322.87° F)
Orbit: Takes 84 years to complete an orbit.
Average Distance: 2,870,972,200 km (1,783,939,400 miles - 19.2 AU) from Sun
Mass: 8.6849 x 1025 kg
Moons: 27
Period of Rotation: 17.24 hours (retrograde: spins backwards compared to most other planets)

Missions to Uranus:


Voyager 2 - January 24, 1986


Uranus in history:


Uranus was mistaken at first for a star first time in 1690 by Jon Flamsteed, cataloging it as 35 Tauri, then the French astronomer Pierre Lemonnier observed it at least twelve times between 1750 and 1769.


After this Sir William Herschel observed the planet on March 13, 1781 in his garden but initially reported it om April 26, 1781 as a "comet". Herschel was using a telescope of his own design.


In his journal he recorded On March 17:  "I looked for the Comet or Nebulous Star and found that it is a Comet, for it has changed its place". When he presented his discovery to the Royal Society, he continued to assert that he had found a comet while also implicitly comparing it to a planet.

Herschel notified the Astronomer Royal, Nevil Maskelyne, of his discovery and received this flummoxed reply from him on April 23: "I don't know what to call it. It is as likely to be a regular planet moving in an orbit nearly circular to the sun as a Comet moving in a very eccentric ellipsis. I have not yet seen any coma or tail to it".

While Herschel continued to cautiously describe his new object as a comet, other astronomers had already begun to suspect otherwise. Russian astronomer Anders Johan Lexell was the first to compute the orbit of the new object and its nearly circular orbit led him to a conclusion that it was a planet rather than a comet. Berlin astronomer Johann Elert Bode described Herschel's discovery as "a moving star that can be deemed a hitherto unknown planet-like object circulating beyond the orbit of Saturn". Bode concluded that its near-circular orbit was more like a planet than a comet.

The object was soon universally accepted as a new planet. By 1783, Herschel himself acknowledged this fact to Royal Society president Joseph Banks: "By the observation of the most eminent Astronomers in Europe it appears that the new star, which I had the honour of pointing out to them in March 1781, is a Primary Planet of our Solar System." In recognition of his achievement, King George III gave Herschel an annual stipend of £200 on the condition that he move to Windsor so that the Royal Family could have a chance to look through his telescopes.


Uranus internal structure: 



Uranus has a mass of roughly 14.5 times that of the Earth, making it the least massive giant planet. Its diameter is slightly larger than Neptune's at roughly four times Earth's. A resulting density of 1.27 g/cm3 makes Uranus the second least dense planet, after Saturn. This indicates that it is made primarily of various ices, such as water, ammonia and methane. The total mass of ice in Uranus's interior is not precisely known, it must be between 9.3 and 13.5 Earth masses. Hydrogen and helium constitute only a small part of the total, with  between 0.5 and 1.5 Earth masses, the remainder of the non-ice mass, 0.5 to 3.7 Earth masses, is accounted for by rocky material.


In standard model of Uranus internal structure consists of three layers: a rocky (silicate/iron-nickel) core in center, an icy mantle in the middle and an outer gaseous hydrogen/helium envelope. The core is relatively small, with a mass of only 0.55 Earth masses and a radius less than 20% of Uranus's; the mantle comprises the bulk of the planet, with around 13.4 Earth masses, while the upper atmosphere is relatively insubstantial, weighing about 0.5 Earth masses and extending for the last 20% of Uranus's radius. Uranus's core density is around 9 g/cm3, with a pressure in the center of 8 million bars and a temperature of 5000K. The ice mantle is not in fact composed of ice in the conventional sense, but of a hot and dense fluid consisting of water, ammonia and other volatiles. This fluid has a high electrical conductivity is sometimes called a water-ammonia ocean. The bulk compositions of Uranus and Neptune are very different from those of Jupiter and Saturn, with ice dominating over gases, hence justifying their separate classification as ice giants. There may be a layer of ionic water where the water molecules break down into a soup of hydrogen and oxygen ions and deeper down superionic water in which the oxygen crystallizes but the hydrogen ions move freely within the oxygen lattice.

Other models are also in satisfaction with the observations. For instance, if substantial amounts of hydrogen and rocky material are mixed in the ice mantle, the total mass of ices in the interior will be lower and correspondingly, the total mass of rocks and hydrogen will be higher. Presently available data does not allow science to determine which model is correct.


Rings of Uranus:





Uranus has a complicated planetary ring system (the second such system to be discovered in our Solar System after Saturn's). The rings composition is from a extremely dark particles, which vary in size from micrometers to a fraction of a meter. All rings are extremely narrow, except two of them. The rings are probably quite young and the dynamics considerations indicate that they did not form with Uranus so the matter in the rings may have been part of a moon or moons that was shattered by high speed impacts.

| la 7:28 AM | 0 comentarii

Saturn


Diameter: 120,660 km. It is about 10 times larger than our Earth
Temperature: –178°C
Distance from Earth: At its closest, Saturn is 1190.4 million km
Atmosphere: Hydrogen and helium
Surface: consists of liquid and gas.
Rotation of its axis: 10 hours, 40 min, 24 sec
Rotation around the Sun: 29.5 Earth years

Missions to Saturn:

 -  
Pioneer 11 in September 1979

-
  Voyager 1 in November 1980
-  Voyager 2 in August 1981

 - Cassini–Huygens spacecraft in July 1, 2004



Saturn in History: 

Because is visible whit the naked eye, Saturn was known from ancient times:


Babylonian astronomers systematically observed and recorded the movements of Saturn. In Roman mythology, the god Saturnus, from whici the planet takes its name, was the god of agricultural and harvest sector. They considered Saturnus the equivalent of  the Greek god Cronus so as usual Greeks associates a particular star whit a god and the Romans followed suit.


In Hindu astrology, Saturn is known as "Shani", the one that judges everyone based on the good and bad deeds performed in life. In the 5th century CE, the Indian astronomical text Surya Siddhanta estimated the diameter of Saturn whit a remarkable precision by more then 99%. Ancient Chinese and Japanese designated the planet Saturn as the earth star, based on the Five Elements which were traditionally used to classify natural elements.

In Hebrew, Saturn is called "Shabbathai" and in ottoman Turkish, Urdu and Malay, its name is "Zuhal", derived from Arabic.

European observations (17th–19th centuries):
Galileo was first to saw the ring as two moons on Saturn's sides and only when Christian Huygens used greater telescopic magnification this notion was refuted. Huygens was also the one ho discovered Saturn's moon Titan. Giovanni Domenico Cassini discovered four other moons: Iapetus, Rhea, Tethys and Dione. He also discovered the gap now known as the Cassini Division.

Almost 150 ears later William Herschel discovered two further moons, Mimas and Enceladus.

And in 1899 William Henry Pickering discovered Phoebe, a highly irregular satellite that does not rotate synchronously with Saturn as the larger moons do. Phoebe was the first such satellite found and it takes more than a year to orbit Saturn in a retrograde orbit. During the early 20th century, research on Titan led to the confirmation in 1944 that it had a thick atmosphere, a feature unique among the solar system's moons.


Saturn internal structure: 


Saturn's internal structure is similar to that of Jupiter, having a small rocky core surrounded mostly by hydrogen and helium. The rocky core is similar in composition to the Earth, but much more dense. Core is surrounded by a thicker liquid metallic hydrogen layer, followed by a liquid hydrogen/helium layer and a gaseous region is estimated to be about 9-22 times the mass of the Earth. The temperature of Saturn's core is about 11,700  °C and radiates 2.5 times more energy into space than it receives from the Sun. Most of this extra energy is generated by the Kelvin - Helmholtz mechanism (slow gravitational compression), but this alone may not be sufficient to explain Saturn's heat production. It is possibely that an additional mechanism might be at play whereby Saturn generates some of its heat through the "raining out" of droplets of helium deep in its interior, thus releasing heat by friction as they fall down through the lighter hydrogen. The interior is estimated to be about 25,000 km across.



Saturn atmosphere:


Saturn has an outer atmosphere of 96.3% molecular hydrogen and 3.25% helium. Also have been detected trace amounts of ammonia, acetylene, ethane, phosphine and methane.
The upper clouds on Saturn are made of ammonia crystals, while the lower level clouds apper to be composed of either ammonium hydrosulfide or water. The atmosphere of Saturn is significantly deficient in helium relative to abundance of the elements in the Sun.

Rings of Saturn:




Saturn is best known for its planetary ring, which makes it the most visually remarkable object in the solar system. The rings extend from 6,600 km to 120,700 km above Saturn's equator.
Composition of the rings is a 93$ water ice with a smattering of thlion impurities and 7% amorphous carbon. The particles that make up the ring range in size from specks of dust up to 10m..
There are two main theories about the formation of the rings. One of them is that the rings are remnants of a destroyed moon of Saturn and the second theory is that the rings are left over from the original nebula material from which Saturn formed. Some ice in the central rings comes from the moon Enceladus' ice volcanoes.


Beyond the main rings at a distance of 12 million km from the planet is the spare Phoebe ring, which is tilted at an angle of 27°  to the other rings and like Phoebe, orbits in retrograde fashion. Some of the moons of Saturn act as shepherd moons to keep the planetary ring stable and prevent them from escaping. Pan and Atlas, two of Saturn moons, cause weak, linear density waves in Saturn's rings that have yielded more reliable calculations of their masses.


The age of these planetary rings is probably hundreds of millions of years old (in contrast to previous thoughts that the rings formed alongside the planet when it formed billions of years ago) and their fate include spiraling inward towards the planet, or the boulders forming the rings colliding with each other and disappearing.





| la 10:55 AM | 0 comentarii

Jupiter



Diameter: 85,788 miles the largest planet - more than 12 Earths could line up across it
Temperature: Range -163° C to >-121° C
Distance from Sun: Approximately 466 million miles
Atmosphere: Mostly hydrogen and helium
Surface: A giant ball of mostly hydrogen and helium
Rotation of its axis: 9 hours, 55 minutes in Earth time (the length of one rotation)
Rotation around the Sun: 12 Earth years
Magnetic Field: Yes
Number of Moons: 63 moons have been identified Ganymede is the largest moon - it is bigger than both Mercury and Pluto


Missions to Jupiter: 

Pioneer 10                      -                          December 3, 1973
Pioneer 11                      -                          December 4, 1974
Voyager 1                      -                          March 5, 1979
Voyager 2                      -                          July 9, 1979
Ulysses                           -                          February 8, 1992 and February 4, 2004
Cassini                           -                          December 30, 2000
New Horizons               -                           February 28, 2007


Jupiter in history:


The name of Jupiter comes from the Romans (latin: Iuppiter,   Iūpiter and also called Jove), the principal god of Roman mythology, whose name comes from the Proto-Indo-European vocative compound...   Dyēu-pəter (nominative: *Dyēus-pətēr, meaning "O Father Sky-God", or "O Father Day-God").



Jupiter has been known since ancient times because it is visible to the naked eye in the night sky and sometimes can be seen in the daytime when the sun is low.


For Babylonians, this object represented their god Marduk and they used a 12 year orbit of this planet along the ecliptic to define the constellations of their zodiac.

In astronomical symbolistic Jupiter is a stylized representation of the god's lighting bolt. The original Greek deity, Zeus, adopted by Romans.

The adjectival form of Jupiter is Jovian. The older adjectival from jovial, employed by astrologers in the Middle Ages, has come to mean "happy" or "merry", the moods ascribed to Jupiter's astrological influence.

For the Japanese, Korean and Chinese civilization Jupiter is the wood star. This comparation is based on the Chinese Five Elements.

Hindu astrologers baned the planet after Brihaspati, the religious teacher of the gods, and often called it "Guru", which literally means the "Heavy One"

In English, Thursday is derived from "Thor's day", Thor was associated with the planet Jupiter in Germanic mythology.

Jupiter internal structure:

Is thought that Jupiter has a dense core with a mixture of elements, a surrounding layer of liquid metallic hydrogen with some helium and an outer layer predominantly of molecular hydrogen. Beyond this basic outline composition is unknown as are the properties of materials at the temperatures and pressure of those depths.The existence of a core is suggested by a gravitational measurements made in 1997, indicating a mass of 12 to 45 times then Earth's mass or roughly 3%-15% of the mass of Jupiter.


The core region is surrounded by dense metallic hydrogen, which extends outward to about 78 percent of the radius of the planet. Rain-like droplets of helium and neon precipitate downward through this layer, depleting the abundance of these elements in the upper atmosphere.

Above the layer of metallic hydrogen lies a transparent interior atmosphere of hydrogen. At this depth, the temperature is above the critical temperature, which for hydrogen is only 33 K. In this state, there are no distinct liquid and gas phases - hydrogen is said to be in a supercritical fluid state. It is convenient to treat hydrogen as gas in the upper layer extending downward from the cloud layer to a depth of about 1,000 km, and as liquid in deeper layers. Physically, there is no clear boundary - gas smoothly becomes hotter and denser as one descends.

The temperature and pressure inside Jupiter increase steadily toward the core. At the phase transition region where hydrogen - heated beyond its critical point - becomes metallic, it is believed the temperature is 10,000 K and the pressure is 200 GPa. The temperature at the core boundary is estimated to be 36,000 K and the interior pressure is roughly 3,000 - 4,500 GPa.

Jupiter atmosphere:


The atmosphere of Jupiter is the largest planetary atmosphere in the Solar System. Mostly made of molecular hydrogen and helium in roughly solar proportions; other chemical compounds are present only in small amounts and include methane, ammonia, hydrogen sulfide and water.

The Jovian atmosphere shows a wide range of active phenomena, including band instabilities, cyclones and anticyclones, storms and lighting.

Jupiter has powerful storms, always accompanied by lighting strikes. The storms are a result of moist convection in the atmosphere connected to the evaporation and condensation of water. They are sites of strong upward motion of the air, which leads to the formation of bright and dense clouds. The lightning strikes on Jupiter are more powerful than those on Earth, however, there are fewer of them.

Jupiter rings:



Jupiter has a faint planetary ring system composed of three main segments: an inner torus of particles known as the halo, a relatively bright main ring and an outer gossamer ring. There rings apper to be made of dust, rather than ice as with Saturn's rings.


The main ring is probably made of material ejected from the satellites Adrastea and Metis. This material dose not fall back to the moon because Jupiter is pulling it whit his strong gravitational influence so the ring is a constant flow of material from the moons to Jupiter. Another ring is created by moons Thebe and Amalthea composed of dust. There is also evidence of a rocky ring strung along Amalthea's orbit which may consist of collisional debris from that moon.

 

| la 4:06 PM | 0 comentarii

Mars


Number of Satellites: 2 (Phobos and Deimos)
Rotation Period: 24 hours and 37 minutes
Temperature: -140 to 20 degrees celsius (-220 to 60 fahrenheit)
Length of Year: About 1 Earth-year and ten and a half months (687 days)
Diameter: 6796 Km (4223 Miles)
Axial Tilt: 25.19 degrees
Atmosphere: Mainly Carbon Dioxide
Magnetic field: No (partial)


Missions to Mars:

Marsnik 1 (Mars 1960A)      -       10 October 1960      -       Attempted Mars Flyby (Launch Failure)
Marsnik 2 (Mars 1960B)      -       14 October 1960      -       Attempted Mars Flyby (Launch Failure)
Sputnik 22                            -       24 October 1962      -       Attempted Mars Flyby
Mars 1                                  -        1 November 1962      -       Mars Flyby (Contact Lost)
Sputnik 24                             -        4 November 1962      -       Attempted Mars Lander
Mariner 3                               -        5 November 1964      -       Attempted Mars Flyby
Mariner 4                              -       28 November 1964      -       Mars Flyby
Zond 2                                 -        30 November 1964      -       Mars Flyby (Contact Lost)
Zond 3                                -         18 July 1965                -         Lunar Flyby, Mars Test Vehicle
Mariner 6                             -         25 February 1969      -       Mars Flyby
Mariner 7                             -         27 March 1969          -        Mars Flyby
Mars 1969A                        -         27 March 1969         -         Attempted Mars Orbiter (Launch Failure)
Mars 1969B                        -           2 April 1969           -         Attempted Mars Orbiter (Launch Failure)
Mariner 8                             -          8 May 1971            -         Attempted Mars Flyby (Launch Failure)
Cosmos 419                        -         10 May 1971           -         Attempted Mars Orbiter/Lander
Mars 2                                -         19 May 1971           -         Mars Orbiter/ Attempted Lander
Mars 3                                -         28 May 1971            -        Mars Orbiter/ Lander
Mariner 9                             -        30 May 1971           -        Mars Orbiter
Mars 4                                -         21 July 1973            -         Mars Flyby (Attempted Mars Orbiter)
Mars 5                                -         25 July 1973           -         Mars Orbiter
Mars 6                                -         5 August 1973        -         Mars Lander (Contact Lost)
Mars 7                                -         9 August 1973         -         Mars Flyby (Attempted Mars Lander)
Viking 1                              -         20 August 1975        -         Mars Orbiter and Lander
Viking 2                               -        9 September 1975    -       Mars Orbiter and Lander
Phobos 1                             -         7 July 1988              -       Attempted Mars Orbiter/Phobos Landers
Phobos 2                            -       12 July 1988               -       Mars Orbiter/Attempted Phobos Landers
Mars Observer                   -       25 September 1992      -       Attempted Mars Orbiter (Contact Lost)
Mars Global Surveyor         -       07 November 1996      -       Mars Orbiter
Mars 96                               -       16 November  1996    -         Attempted Mars Orbiter/Landers
Mars Pathfinder                  -         04 December 1996      -       Mars Lander and Rover
Nozomi (Planet-B)             -         3 July 1998                -         Mars Orbiter
Mars Climate Orbiter         -         11 December 1998      -       Attempted Mars Orbiter
Mars Polar Lander              -        3 January 1999          -         Attempted Mars Lander
Deep Space 2 (DS2)           -         3 January 1999         -        Attempted Mars Penetrators
2001 Mars Odyssey            -        7 April 2001              -         Mars Orbiter
Mars Express                      -         2 June 2003              -        Mars Orbiter and Lander
Spirit (MER-A)                  -        10 June 2003             -         Mars Rover
Opportunity (MER-B)        -         7 July 2003               -         Mars Rover
Mars Reconnaissance Orbiter -    10 August 2005         -         Mars Orbiter
Phoenix                              -         04 August 2007         -        Mars Scout Lander
Phobos-Grunt                    -         08 November 2011    -       Martian Moon Phobos Lander
Yinghuo-1                         -        08 November 2011      -       Mars Orbiter
Mars Science Laboratory  -        25 November 2011       -  Mars Rover
MAVEN                            -        18 November 2013 (planned) -  Mars Scout Mission Orbiter



Mars in history:


Mars was regarded as a malevolent agent of war, pestilence and apocalyptic disaster. Often in an attempt to calm down the planet-god, various ancient cultures offered it human sacrifices. This concept of a evil god was found in the New World as well as the Old one.



In Babylonian civilization Mars was identified as the god of war Nergal. Deity of the desert, god of fire, god of war, which is one of negative aspects of the sun, god of the underworld, and also being a god of one of the religions which rivaled Christianity and Judaism, Nergal was sometimes called a demon and even being identified with Satan. According to Collin de Plancy and Johann Weyer, Nergal was said to be the chief of Hell's "secret police", and said to be "an honorary spy in the service of Beelzebub".
Greeks called this planet Ares their god of war. Ares was the great Olympian god of war, civil order and manly courage. In Greek art he was depicted as either a mature, bearded warrior dressed in battle arms, or a nude beardless youth with helm and spear.

In Mayan, Mars is depicted as a long nosed monster or animal, hanging from a band that stretch across the sky and sometimes Mars is depicted to be a regular human.

In recent history Mars was believed to be the home of green aliens which were forced to live inside artificial structures named "canals" and in present time Mars is the best candidate for alien life form, but this time microbiological life.



Geology:

Mars has a meteorite collection on the surface whit the primarily composed of basalt. Some evidence suggets that a portion of Martian surface is more silica-rich than typical basalt and may be similar to Andesitic rocks from Earth, these observation explained by the presence of silica glass. Much of the surface is deeply covered in grained iron oxide dust (from which the red color comes).

Although Mars has no current structured global magnetic field, observations show that parts of the planet's crust have been magnetized and that alternating polarity reversals of its dipole field have occurred in the past. This paleomagnetism of minerals has properties very similar to the alternating bands found on the ocean floors on Earth. These bands also demonstrate that around four billion years ago on Mars where tectonic plates, before the planetary dynamo ceased to function and caused the planet's magnetic field to fade away.

In current models of the planet the interior has a core region about 1,480 km radius, consisting primarily of iron with about 14-17% sulfur. This iron sulfide core is partially fluid and has twice the concentration of the lighter elements than exist at Earth's core. The core is surrounded by a silicate mantle that formed many of tectonic and volcanic features on the planet, but now appears to be inactive. The planet crust has an average thickness of about 50 km, with a maximum thickness of 125 km. Earth's crust is averaging to 40 km and it is only one third as thick as Mars crust, relative to the size of the two planets.

In the formation of the Solar System Mars was created out of the protoplanetary disk that orbited the Sun as the result of a stochastic process of run-away accretion. Mars has a many distinctive chemical features caused by its position in the Solar System. Elements with low boiling points such as chlorine, phosphorus and sulphur are much more common on Mars than Earth.

After the formation of the planets about 60% of the surface of Mars shows an impact record from that era. Much of the rest of the surface of Mars is probably underlain by immense impact basins that date from this time and in norther hemisphere of Mars is a crater spanning 10,600 km by 8,500 km (about four times larger that the Moon's South Pole-Aitken basin), this suggests that Mars was struck by a Pluto sized body about four billion years ago. This event created the smooth Borealis basin that covers 40% of the planet.

In the geological history of Mars there are three main periods:
- Noachian period (named after Noachis Terra): Formation of the oldest extant surfaces of Mars, 4.5 billion years ago to 3.5 billion years ago.  Noachian age surfaces are scarred by many large impact craters. The volcanic upland is thought to have formed during this period with extensive flooding by liquid water late in the period.
- Hesperian period (named after Hesperia Planum): 3.5 billion years ago to 2.9-3.3 billion years ago. This period is marked by the formation of extensive lava plains.
_ Amazonian period (named after Amazonis Planitia): 2.9 - 3.3 billion years ago to present. Amazonian regions have few meteorite impact craters, but are otherwise quite varied. Olumpus Mons formed during this period along with lava flows elsewhere on Mars.

Mars is still have some geological activity. The Athabasca Valles is to sheet-like lava flows. Water flows in the grabens called the Cerberus Fossae. On February 19. 2008 images from Mars Reconnaissance Orbiter showed evidence of an avalanche from a 700 m high cliff.

| la 10:59 AM | 0 comentarii

Venus


 Diameter: 12,100 km. It is about 1040km smaller in diameter than Earth
 Temperature: Ranges from 900F+/- 50F (about 500°C +/- 32°C) at the surface
 Distance from Earth: At its closest, Venus is 41,840,000 km away
 Atmosphere: Carbon dioxide (95%), nitrogen, sulfuric acid, and traces of other elements
 Surface: A rocky, dusty, waterless expanse of mountains, canyons, and plains, with a 200-mile river of hardened lava
 Rotation of its axis: 243 Earth days (1 Venusian Day)
 Rotation around the Sun: 225 Earth days
 Magnetic Field: week


Missions to Venus:
USSR - Sputnik 7               -        February 4, 1961               -        Impact (attempted)
USSR - Venera 1                -          February 12, 1961           -        Flyby (contact lost)
USA   - Mariner 1               -          July 22, 1962                   -        Flyby (launch failure)
USSR - Sputnik 19              -          August 25, 1962              -        Flyby (attempted)
USA   - Mariner 2                -          August 27, 1962             -        Flyby
USSR - Sputnik 20              -          September 1, 1962          -        Flyby (attempted)
USSR - Sputnik 21              -          September 12, 1962        -       Flyby (attempted)
USSR - Cosmos 21             -          November 11, 1963        -        Attempted Venera test flight?
USSR - Venera 1964A        -        February 19, 1964            -        Flyby (launch failure)
USSR - Venera 1964B        -         March 1, 1964                 -        Flyby (launch failure)
USSR - Cosmos 27             -          March 27, 1964              -        Flyby (attempted)
USSR - Zond 1                    -          April 2, 1964                  -        Flyby (contact lost)
USSR - Venera 2                 -          November 12, 1965       -        Flyby (contact lost)
USSR - Venera 3                 -          November 16, 1965       -        Lander (contact lost)
USSR - Cosmos 96              -          November 23, 1965       -        Lander (attempted?)
USSR - Venera 1965A         -          November 23, 1965       -        Flyby (launch failure)
USSR - Venera 4                  -          June 12, 1967                -         Probe
USA   - Mariner 5                 -          June 14, 1967                -         Flyby
USSR - Cosmos 167             -          June 17, 1967               -         Probe (attempted)
USSR - Venera 5                   -          January 5, 1969            -         Probe
USSR - Venera 6                   -          January 10, 1969           -         Probe
USSR - Venera 7                   -          August 17, 1970           -         Lander
USSR - Cosmos 359             -          August 22, 1970           -         Probe (attempted)
USSR - Venera 8                  -          March 27, 1972            -         Probe
USSR - Cosmos 482            -          March 31, 1972            -         Probe (attempted)
USA   - Mariner 10              -         November 4, 1973          -         Flyby Mercury flyby
USSR - Venera 9                 -         June 8, 1975                   -         Orbiter and lander
USSR - Venera 10               -          June 14, 1975                -         Orbiter and lander
USA   - Pioneer Venus 1      -          May 20, 1978                -          Orbiter
USA   - Pioneer Venus 2      -          August 8, 1978              -          Probes
USSR - Venera 11               -          September 9, 1978         -         Flyby bus and lander
USSR - Venera 12               -          September 14, 1978       -        Flyby bus and lander
USSR - Venera 13               -         October 30, 1981            -          Flyby bus and lander
USSR - Venera 14               -          November 4, 1981          -         Flyby bus and lander
USSR - Venera 15               -          June 2, 1983                   -          Orbiter
USSR - Venera 16               -          June 7, 1983                   -          Orbiter
USSR - Vega 1                    -          December 15, 1984       -          Lander and balloon Comet Halley flyby
USSR - Vega 2                    -          December 21, 1984       -        Lander and balloon Comet Halley flyby
USA   - Magellan                 -          May 4, 1989                  -          Orbiter
USA   - Galileo                    -          October 18, 1989          -          Flyby Jupiter orbiter/probe
USA   - Cassini                    -          October 15, 1997          -          Flyby Saturn orbiter
USA   - MESSENGER        -          August 3, 2004               -          Flyby (x2) Mercury orbiter
ESA    - Venus Express         -         November 9, 2005         -          Orbiter
JPN    - Akatsuki                 -          December 7, 2010       - Orbiter (attempted) Possible reattempt in 2016
JPN   -  BepiColombo         -          July 2014                     -   Flyby (x2, Planned) Planned Mercury orbiter

Venus in history:


Because Venus is the brightest object in the sky, this planet is known since prehistoric times and as such has gained an entrenched position in human culture. In Sumerian times Venus was named Inanna (Babylonian Ishtar) the goddess of love.

In Ancient Egypt was believed that Venus is two separate bodies named the morning star (Tioumoutiri) and the evening star (Ouaiti). Likewise, believing Venus to be two bodies, the Ancient Greeks called the the morning star Phosphorus, the "Bringer of Light" or Eosphoros the "Bringer of Dawn" and the evening star by the name of Hesperos "star of the evening". By Hellenistic times, the ancient Greeks realized the two were the same planet and named it after the goddess of love, Aphrodite. In latin Hesperos would be translated as Vesper and Phosphoros as Lucifer ("Light Bearer"), a poetic term later used to refer to the fallen angel cast out of heaven.
Romans as other civilizations have named the planet Venus after their goddess of love (Venus). In Persian mythology, the planet correspods to the goddess Anahita. In Some parts of Pahlavi literature whit Aredvi Sura and Anahita two separate entities, the first one is a personification of the mythical river and the latter as a goddess of fertility.

Venus was important to the Maya civilization, who developed a religious calendar based in part upon its motions, and held the motions of Venus to determine the propitious time for important events. The named it Noh Ek', in translation "the Great Star" and Xux Ek' "the Wasp Star". The Maya were aware of the planet's synodic period (a synodic day is the period of time it takes for a planet to rotate once in relation to the body it is orbiting) and could commute it to within a hundredth part of a day.

Venus is also important in many Australian aboriginal cultures, such as that of the Yolngu people in Northern Australia. The Yolngu gather after sunset to await the rising of Venus, which they call Barnumbirr. As she approaches, in the early hours before dawn, she draws behind her a rope of light attached to the Earth, and along this rope, with the aid of a richly decorated "Morning Star Pole", the people are able to communicate with their dead loved ones, showing that they still love and remember them. Barnumbirr is also an important creator-spirit in the Dreaming, and "sang" much of the country into life.

Venus plays a prominent role in Pawnee mythology. The Pawnee, a North American native tribe, until as late as 1838, practiced a morning star ritual in which a girl was sacrificed to the morning star.

Shukra is the Sanskrit name for Venus

In western astrology, derived from its historical connotation with goddesses of femininity and love, Venus is held to influence desire and sexual fertility. In Indian Vedic astrology, Venus is known as Shukra, meaning "clear, pure" or "brightness, clearness" in Sanskrit. One of the nine Navagraha, it is held to affect wealth, pleasure and reproduction; it was the son of Bhrgu, preceptor of the Daityas, and guru of the Asuras. Modern Chinese, Korean, Japanese and Vietnamese (citation needed) cultures refer to the planet literally as the “metal star” (金星), based on the Five elements.

Physical characteristics:

Venus is one of the four rocky planets in our solar system whit a size and mass very similar to the Earth and often described as Earth's "sister" or "twin". Venus has a diameter only 650 km less than the Earth's and its mass is 81.5% of the Earth's. But condition of Venusian surface differ radically from those on Earth, due to its dens carbon dioxide atmosphere (atmosphere of Venus contains 96.5% carbon dioxide, with most of the remaining 3.5% being nitrogen).

Internal structure:

Without seismic data or knowledge of its moment of inertia, there is little direct information about the internal structure and geochemistry of Venus. The similarity in size and density between Venus and Earth suggests that they share a similar internal structure: a core, mantle, and crust. Like that of Earth, the Venusian core is at least partially liquid because the two planets have been cooling at about the same rate. The slightly smaller size of Venus suggests that pressures are significantly lower in its deep interior than Earth. The principal difference between the two planets is the lack of plate tectonics on Venus, likely due to the dry surface and mantle. This results in reduced heat loss from the planet, preventing it from cooling and providing a likely explanation for its lack of an internally generated magnetic field.

Surface geography and geology:

About 80% of the Venusian surface is covered by smooth volcanic plains, consisting of 70% plains with wrinkle ridges and 10% smooth plains. Two highland "continents" make up the rest of its surface area, one lying in the planet's northern hemisphere and the other just south of the equator.
The northern continent is called Ishtar Terra, after Ishtar, the Babylonian goddess of love, and is about the size of Australia. Maxwell Montes, the highest mountain on Venus, lies on Ishtar Terra whit his peak at 11 km above the Venusian average surface elevation.
The southern continent is called Aphrodite Terra, after the Greek goddess of love, and is the larger of the two highland regions at roughly the size of South America. A network of fractures and faults covers much of this area.

Mountains as well as the impact craters and valleys commonly found on rocky planets, Venus has a number of unique surface features. Among these are flat-topped volcanic features called farra, which look somewhat like pancakes and range in size from 20–50 km across, and 100–1,000 m high; radial, star-like fracture systems called Novae, features with both radial and concentric fractures resembling spider webs, known as Arachnoids; and Coronae, circular rings of fractures sometimes surrounded by a depression. These features are volcanic in origin.

The longitudes of physical features on Venus are expressed relative to its prime meridian. The original prime meridian passed through the radar-bright spot at the center of the oval feature Eve, located south of Alpha Regio. After the Venera missions were completed, the prime meridian was redefined to pass through the central peak in the crater Ariadne.



Much of the Venusian surface appears to have been shaped by volcanic activity. Venus has several times as many volcanoes as Earth, and it possesses some 167 large volcanoes that are over 100 km across. The only volcanic complex of this size on Earth is the Big Island of Hawaii. This is not because Venus is more volcanically active than Earth, but because its crust is older. Earth's oceanic crust is continually recycled by subduction at the boundaries of tectonic plates and has an average age of about 100 million years, while the Venusian surface is estimated to be 300–600 million years old.

Several lines of evidence point to ongoing volcanic activity on Venus. During the Soviet Venera program, the Venera 11 and Venera 12 probes detected a constant stream of lightning and Venera 12 recorded a powerful clap of thunder soon after it landed. The European Space Agency's Venus Express recorded abundant lightning in the high atmosphere. While rainfall drives thunderstorms on Earth, there is no rainfall on the surface of Venus (though it does rain sulfuric acid in the upper atmosphere that evaporates around 25 km above the surface). One possibility is that ash from a volcanic eruption was generating the lightning. Another piece of evidence comes from measurements of sulfur dioxide concentrations in the atmosphere, which were found to drop by a factor of 10 between 1978 and 1986. This may imply that the levels had earlier been boosted by a large volcanic eruption.


There are almost a thousand impact craters on Venus evenly distributed across its surface. On other cratered bodies, such as the Earth and the Moon, craters show a range of states of degradation. On the Moon, degradation is caused by subsequent impacts, while on Earth, it is caused by wind and rain erosion. On Venus, about 85% of craters are in pristine condition. The number of craters, together with their well-preserved condition, indicates that the planet underwent a global resurfacing event about 300–600 million years ago, followed by a decay in volcanism. Earth's crust is in continuous motion, but it is thought that Venus cannot sustain such a process. Without plate tectonics to dissipate heat from its mantle, Venus instead undergoes a cyclical process in which mantle temperatures rise until they reach a critical level that weakens the crust. Then, over a period of about 100 million years, subduction occurs on an enormous scale, completely recycling the crust.

Magnetic field and core:

In 1967, Venera-4 found that the Venusian magnetic field is much weaker than that of Earth. This magnetic field is induced by an interaction between the ionosphere and the solar wind, rather than by an internal dynamo in the core like the one inside the Earth. Venus' small induced magnetosphere provides negligible protection to the atmosphere against cosmic radiation. This radiation may result in cloud-to-cloud lightning discharges.

The lack of an intrinsic magnetic field at Venus was surprising given that it is similar to Earth in size, and was expected also to contain a dynamo at its core. A dynamo requires three things: a conducting liquid, rotation, and convection. The core is thought to be electrically conductive and, while its rotation is often thought to be too slow, simulations show that it is adequate to produce a dynamo. This implies that the dynamo is missing because of a lack of convection in the Venusian core. On Earth, convection occurs in the liquid outer layer of the core because the bottom of the liquid layer is much hotter than the top. On Venus, a global resurfacing event may have shut down plate tectonics and led to a reduced heat flux through the crust. This caused the mantle temperature to increase, thereby reducing the heat flux out of the core. As a result, there is not an internal geodynamo that can drive a magnetic field. Instead the heat energy from the core is being used to reheat the crust.

One possibility is that Venus has no solid inner core or its core is not currently cooling, so that the entire liquid part of the core is at approximately the same temperature. Another possibility is that its core has already completely solidified. The state of the core is highly dependent on the concentration of sulfur, which is unknown at present.b

| la 5:03 PM | 1 comentarii

Mercury


History:

The early records about Mercury can be found in the Babylonian and Sumerian writings, about 3000 years ago. The planet is also mentioned in Ancient China, India, and in the documents laying in the tombs of Egypt. Mercury has and still is hard to see because it does not orbit far from the Sun. This problem was also encountered by the ancient astronomers.

Ancient Greeks called Mercury either Apollo or Hermes. Its present name was given by the Romans, due to the fact that Mercury moves fast before the dawn and after the sunset.

In the recent history, Mercury is believedto be first observed by Johann Hieronymus. He drew the surface of Mercury and kept a record of it in his notes. Schroeteralso studied the planet, until his death in 1816. Moreover, Mercury was observed by Percival Lowell and Schia too, whonoticed dark streaks on Mercury's surface. They thought those were the same canals seen on planet Mars but with the use of a more advanced telescope, EugeniosAntoniadi was later able to map out the surface of Mercury. From his notes, it has been discovered that these so-called Martian canals were just an optical illusion. In present,Mercury images comes from Mariner 10, the first robot that photographed our closest and smallest planet.

Because Mercury is so close to the Sun, there is no atmosphere.

Mercury is 4879 (km) across. That makes Mercury just less than half the size of the Earth.

Mercury has craters like those on the Earth's moon. The largest crater on Mercury is Caloris Basin. It is about 1300 km wide. It was created by a huge asteroid which hit Mercury. The asteroid was probably 100 km wide.

The surface also has big cliffs called scarps. They were created when Mercury cooled down. It shrank, causing the surface to get wrinkled in some places. This wrinkling created the scarps.

There may also be ice at the poles of Mercury because there the temperature is much lower.

Mercury gets very hot during the day and very cold at night. It is very hot during the day (over 400°C) because Mercury is so close to the Sun. At night, however, Mercury loses almost all its heat because there is almost no atmosphere to keep it there. The temperature can fall to almost -200°C.

Mercury rotates around his axes much more slowlier than the Earth, so one day on Mercury lasts as long as 58 days on Earth!

Mercury has the shortest year in the Solar System. It is about 88 Earth days long.

Composition:

As far as we know, the center of Mercury is made of iron. It contains more iron for its size than any other planet in the Solar System. The rest of Mercury is made of rock.

| la 12:06 PM | 0 comentarii

Europa


Image source: astronomycentral.co.uk



Europa is one of Jupiter's moon slightly smaller than the Earth's Moon. It is beleaved that Europa has a iron core whit a rocky mantle and a undergraond ocean of slaty water. This ocean is deep enough to cover the whole surface and being far from the sun, the surface of it is globally frozen over. The ocean heat comes from friction forces generated by orbiting arownd massive planet Jupiter.

Europa orbits Jupiter every 3.5 days and is phase locked just like Earth's Moon so one side of it faces Jupiter all the time. The friction is generated because Europa has a eccentric orbit (an oval not a circle orbit) so when it is close to Jupiter the tide is much higher than when it is far from it. Thus tidal forces raise and lower the sea beneath the ice, causing constant motion and very likely causing the cracks seen on the Europa's surface from robotic probes.

This tidal force causes Europa to be warmer that it would otherwise according to his distance of about 780.000.000 Km (485.000.000 miles) from the Sun, more that five time further as the distance from Earth to sun. This heat could prove critical to the survival of simple organisms within the ocean, if they exist.

History:

Discovered on 8 January 1610 by Galileo Galilei along with three other moons. Europa was the first moon discovered orbiting a planet other than Earth. This discovery eventually led to understanding that planets in our solar system orbit the Sun, instead of our solar system revolving around Earth. Galileo apparently had observed Europa on 7 January 1610. but had been unable to differentiate it from Io until next night.

Galileo originally called Europa Medicean planet, after the Medici family. This name was used for a couple of centuries until the mid-1800s wen the moons are renamed, Io, Europa, Ganymede and Callisto because it became apparent that naming moons by number would be very confusing as new additional moons were being discovered.

Europa is named after the daughter of Agenor. Europa was abducted by Zeus (Greek equivalent of the Roman god Jupiter), who had taken the shape of a spotless white bull. Europa was so delighted by the gentle beast that she decked it with flowers and rode upon its back. Zeus seizing his opportunity rode away with her into the ocean to the island of Crete, where he transformed back into his true shape. Europa bore Zeus many children, including Minos.


Mass (kg) - 4.8e+22
Mass (Earth = 1) - 8.0321e-03
Equatorial radius (km) - 1,569
Equatorial radius (Earth = 1) - 2.4600e-01
Mean density (gm/cm^3) - 3.01
Mean distance from Jupiter (km) - 670,900
Rotational period (days) - 3.551181
Orbital period (days) - 3.551181
Mean orbital velocity (km/sec) - 13.74
Orbital eccentricity - 0.009
Orbital inclination (degrees) - 0.470
Escape velocity (km/sec) - 2.02
Visual geometric albedo - 0.64
Magnitude (Vo) - 5.29

| la 7:20 AM | 0 comentarii

Dwarf Planets

In order for a celestrail body or an astromical body to be labeled as a dwarf planet it has to have a orbit around a star, has sufficient mass for it's self-gravity to overcome rigid body forces so that it has a nearly round shape, has not cleared the neighborhood around its orbit and it is not a satellite.

The dwarf planets discovered until now, are: Pluto (It takes 248 Earth days for 1 Pluto year and 6 Earth days for 1 Pluto day), Sedna (It takes 10.500 Earth years for 1 Sedna year and 10.27 Earth hours for 1 Sedna day), Eris (It takes 55 Earth years for 1 Eris year and 8 Earth days for 1 Eris day), Quaoar (It takes 285 Earth years for 1 Quaoar year but the duration of a day on Quaoar is unknown), Ceres (It takes 4.6 Earth years for 1 Ceres year and 1679.819 Earth days for 1 Ceres day)

History of Dwarf Planets:

- The Dwarf Planets got there name by a group of astronomers named the IAU. There were tons of small planets with odd revolution cycles. Instead of adding tons of more planets to the solar system, they made a new group named dwarf planets and Pluto fit into the definition of a dwarf planet. The place were the Dwarf Planets remain in space is behind Neptunes orbit. It is called the Kuiper Belt, named after the astronmer Gerard Kuiper. The Kuiper Belt is a place where remaining building bodies of our solar system are locadet.
- The five common dwarf planets are Pluto, Cires, Eris, Make Make, Haumea.
- Mike Brown estimates that there are more than 200 dwarf planets in the space close to our star.


Moons of Dwarf Planets:

- Pluto's moons are Charon, Nix, and Hydra. Charon was dicovered in 1978. Nix and Hydra where discovred in 2005 at the same time.
- Quaoar- Quaoar has no moons discovered yet.
- Eris- Eris has one moon discovered named Dysnomia.
- Sedna- Sedna has no moons discovered yet.
- Ceres- Ceres also has no moons discovered yet.



Measurement and Size:

-The Kuiper Belt is 4.5 billion km from the sun and it is located behind Neptune orbit whit the smallest diameter of 303 kilometers (185 miles) and the largest one of 2,400 kilometers(1,500 miles). The largest dwarf planet is about five times smaller then the Earth and the smallest one is about fiftey eight times smaller than the Earth.
- Pluto is about 5 billion km from the sun whit a diameter of 2274 km.
- Sedna's diameter is about ¾ the size of Pluto resulting in a diameter of 1,800 km. Sedna is 130 billion kilometers (84 billion miles) away from the San which is 900 times greater that the Earth's solar distance.
- Quaoar has 1250 km in diameter and is his volume is equal whit the volume of 50,000 asteroids. Quaoar is at 4 billion km away from the sun.
- Eris is placed at a average distance of 6.3 billion miles away from the sun and it has the same diameter like Pluto.

Names origin:
- Charon in greek mythology, was the boat man who carried souls of the dead to the underworld. The underworld was a kingdom ruled by the god, Pluto.
- Sedna is the name of a sea goddess. Sedna the Sea Goddess.
- Eris is the Greek Goddess of discord and strife. Eris is evil. Her hobbie is to make trouble. She has an Golden Apple (apple of discord) that is so birght and shiny that everyone wants it. When she throws it among friends, their friendships come to an end and when she throws it among enemies war breaks out. She did this once during the wedding of Peleus and Thetis, this brought the Trojon war.
- The name Quaoar is from Greek Mythology. At the beginning there was chaos, then came Quaoar. He was sad because the emtyness in existince and began to dance, whirl and twirl all around while he sang the song of creation.
- Dysnomia is (the moon of Eris) the mythological daughter of Eris. Dysnomia is the demon spirit of lawlessness.
- Nix is the goddess of Night and the daughter of mischief.
- Hydra is a dog monster with nine indistructible serpent haeds and deadly poisonous blood.

| la 5:00 AM | 0 comentarii

Eris real size



Finally astronomers have accurately measured the size of the remote dwarf planet named Eris . They caught it as it passed in front of a faint star using the occultation technique. Eris also seems to be extremely reflective, probably because it is covered in a thin layer of frozen atmosphere.

Occultations are rather like eclipses —the background star disappears behind the object and reappears on its other side. By looking at these two events, astronomers can measure the size and shape of the occulting foreground object and if they also know the mass of this object they can then determine its density which can be used to determine the composition of the object.

Eris was identified as a large object in the outer Solar System in 2005. Its discovery was one of the factors that led to the creation of a new class of objects called dwarf planets and the reclassification of Pluto from planet to dwarf planet in 2006.

Eris is three times farther from the Sun than Pluto at the moment, and until now was believed to be about 25% bigger. But the new observations show that Eris is in fact almost exactly the same size as Pluto, with a diameter of around 2330 kilometres.


Because Eris also has a moon, called Dysnomia, astronomers have also been able to calculate the mass of Eris by a careful study of this moon's orbit. Using the new diameter and known mass, they then calculated the density of the Eris, which now appears to be greater than astronomers had previously thought. Eris seems to be a rocky body surrounded by a thick mantle of ice.

The dwarf planet turns out to reflect almost all of the light that falls on it — its surface is even brighter than fresh snow on Earth. Eris is probably covered in a very thin layer of frozen atmosphere that is likely to consist of frozen nitrogen mixed with methane. It is probably the result of the freezing of Eris's atmosphere as the dwarf planet's elongated orbit takes it far away from the Sun.
These important new observations, made with relatively small telescopes, have allowed astronomers to measure Eris's properties better than ever before. This is another step towards understanding the mysterious objects that lie in the remote parts of our own Solar System.

| la 4:36 AM | 0 comentarii

Enceladus

Image source: Astrobioloblog



Enceladus the brightest satellite of Saturn, also named Saturn II was discovered by William Herschel in August 28, 1789

Orbital characteristics:
Semi-major axis 237,948 km
Eccentricity 0.004 7
Orbital period 1.370 218 days or 118,386.82 seconds
Inclination 0.019° (to Saturn's equator)

Proper orbital elements
Physical characteristics:

Dimensions 513.2×502.8×496.6 km
Mean radius 252.1 ± 0.2 km (0.0395 Earths)
Mass (1.080 22 ± 0.001 01)×1020 kg (1.8×10−5 Earths)
Mean density 1.609 ± 0.005 g/cm3
Equatorial surface gravity 0.114 m/s2 (0.011 3 g)
Escape velocity 0.239 km/s (860.4 km/h)
Rotation period synchronous
Axial tilt zero
Albedo 1.375 ± 0.008 (geometric) or 0.99 (Bond)[8]
Surface temp. Kelvin
min mean max
32.9 K 75 K 145 K

Apparent magnitude 11.7
Atmosphere
Surface pressure trace, significant spatial variability
Composition 91% Water vapour
4% Nitrogen
3.2% Carbon dioxide
1.7% Methane

Geyser eruption on Enceladus

| la 4:10 PM | 0 comentarii

Saturn's Moons

Image source: Cassini

The dozens of icy moons orbiting Saturn vary drastically in shape, size, surface age and origin. Some of these worlds have hard, rough surfaces, while others are porous bodies coated in a fine blanket of icy particles. All have greater or smaller numbers of craters, and many have ridges and valleys. Some, like Dione and Tethys, show evidence of tectonic activity, where forces from within ripped apart their surfaces. Many, like Rhea and Tethys, appear to have formed billions of years ago, while others, like Janus and Epimetheus, could have originally been part of larger bodies that broke up. The study and comparison of these moons tells us a great deal about the history of the Saturn System and of the solar system at large.

So far, 62 moons have been discovered in Saturn's orbit, and 53 of them have been officially named.
The 53 moons of Saturn in alphabetic order: Aegaeon, Aegir, Albiorix, Anthe, Atlas, Bebhionn, Bergelmir, Bestla, Calypso, Daphnis, Dione, Enceladus, Epimetheus, Erriapus, Farbauti, Fenrir, Fornjot, Greip, Hati, Helene, Hyperion, Hyrrokkin, Iapetus, Ijiraq, Janus, Jarnsaxa, Kari, Kiviuq, Loge, Methone, Mimas, Mundilfari, Narvi, Paaliaq, Pallene, Pan, Pandora, Phoebe, Polydeuces, Prometheus, Rhea, Siarnaq, Skadi, Skoll, Surtur, Suttung, Tarqeq, Tarvos, Telesto, Tethys, Thrym, Titan and Ymir.

Astronomers continue to find new small moons orbiting Saturn, using both ground-based observatories and Cassini's own imaging cameras.

| la 3:53 PM | 0 comentarii

Titan the largest moon of Saturn


Discovered by Christiaan Huygens in March 25, 1655

Titan is also known as Saturn VI

Orbital characteristics are:
Periapsis 1,186,680 km
Apoapsis 1,257,060 km
Semi-major axis 1,221,870 km
Eccentricity 0.0288
Orbital period 15.945 days
Inclination 0.34854 ° (to Saturn's equator)

Physical characteristics:
Mean radius 2,576±2 km (0.404 Earths)
Surface area 8.3×107 km2
Volume 7.16×1010 km3 (0.066 Earths)
Mass 1.3452±0.0002×1023 kg (0.0225 Earths)
Mean density 1.8798±0.0044 g/cm3
Equatorial surface gravity 1.352 m/s2 (0.14 g)
Escape velocity 2.639 km/s
Rotation period Synchronous
Axial tilt Zero
Albedo 0.22
Temperature 93.7 K (−179.5 °C)
Apparent magnitude 8.2 to 9.0

Atmosphere:
Surface pressure 146.7 kPa
Composition Variable
Stratosphere:
98.4% nitrogen (N2),
1.4% methane (CH4);
Lower troposphere:
95% N2, 4.9% CH4

| la 3:22 PM | 0 comentarii

Lakes of Titan


It’s been thought for some time that liquid might exist on Titan, and given its dense atmosphere that’s loaded with hydrocarbons, methane or ethane is a good guess. But evidence has been scant. The best so far was when the Huygens probe, launched by Cassini to land on Titan, appeared to have squished down in mud!

The image above, taken using the Cassini probe’s radar. It’s the shape of the features that’s interesting: sharp-edged, yet with rounded contours. That, plus the fact that liquid methane and ethane absorb radar, making them look dark just like those features, is very provocative. Cassini scientists are excited about the images, so I’m sure we’ll be hearing lots more about this very soon.

People will inevitably wonder if this has any impact on life evolving on Titan. Beats me. We really have no clue how life first sparked on Earth. We need liquid water now, but as far as I know it’s not clear exactly what Earth was like when life first arose (any biologists or archaeologists wanna enlighten us physical scientist-types about this?). And does that situation apply to Titan, with twice the Earth’s atmospheric pressure and temperatures of -180 Celsius?

Still and all, liquid existing on the surface of another world is really exciting. The more we look at other worlds, the more alien we realize they are… but the more like home as well.

| la 3:17 PM | 0 comentarii