Pluto
Pluto used to be a planet, but is
now one of the four (Pluto, Eris, Sedna, Ceris) dwarf planets in the solar
system. Pluto is the god of the underworld in Roman mythology. This is probably
because it gets almost no light as it is extremely far from the sun. Pluto has
three moons, Charon, Nix and Hydra with Charon being the largest. Charon is
almost the size of Pluto itself. Nix and Hydra are much smaller and are only
between 60 and 200 km in diameter. Click on the image of Pluto to learn more
about it and the image of Charon for the same.
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Distance from the sun:
5,913,520,000 km from the Sun (on an average because it sometimes crosses with
the orbit of Neptune)
Diameter: 2274 km 22
Mass: 1.2722 kg
So far, all the information we
know of Pluto comes from ground based observations. There has not been a single
spacecraft that has flown to Pluto. We have, however, launched a spacecraft, New
Horizons, in January 2006 and it should reach Pluto by 2015 if it flies
according to plans.
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Pluto’s orbit is unlike the most
of the other planets in the solar system. First of all, it rotates in an
direction opposite to most of the other planets in the solar system. It has also
got one of the most eccentric (not a perfect circle) orbits in the solar system.
Infact, it is so eccentric that it sometimes orbits in front of Neptune, thus
coming closer to the sun.
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Unlike most of the other outer
planets, Pluto contains only about 30% ices and around 70% rock. The ices may
include carbon monoxide ice, ethane ice, methane ice, and nitrogen ice. The
average temperature is about 38K-63K.
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Pluto does not always an
atmosphere. As Pluto moves farther away from the Sun, more of its atmosphere
freezes and falls to the ground, and when it comes closer to the Sun, the
temperature of Pluto's solid surface increases, causing the nitrogen ice to
sublimate into gas thus creating an anti-greenhouse effect and a temporary
atmosphere. Because no spacecraft has flown to Pluto, we do not know what the
contents of the atmosphere are. However, its is predicted by Scientists that it
may be composed of methane and carbon monoxide, two very poisonous gases.
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Charon’s name comes from two places. Like in all the other planets, Charon’s name has a mythological origin. In Greek mythology, all the dead, were ferried to Hades (Pluto) who was across the river, Acheron, by Charon. Before, Charon was discovered as a moon of Pluto, people used to think that it was part of Pluto, since most of the images at that time were blurred and showed Pluto and Charon as one. Pluto and Charon orbit in such a way that they always keep their same side facing each other.
Fact File
Distance from Pluto: 19,640 km
Diameter: 1212 km
Mass: 1.9021 kg
Surface and Contents
Like most of the other outer planets and their moons, Charon is made up all most completely out of ice. But this is suprising as Pluto is not made out of ice in this way. Astronomers feel that Charon must have been created when an enormous object smashed into Pluto.
1. If you know exactly where to look, and you try very hard, it is possible to see Pluto with a amateur telescope. But you won’t be able to see much at all and it will take a very long time to find it.
2. Pluto crossed the orbit of Neptune in January 1979 and stayed that way for a stunning 20 years until the 11th of February 1999.
3. Another very surprising fact about the orbit of Pluto is that the length of the orbit is exactly one and half times longer than the length of Neptune’s orbit.
