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Pluto

Pluto, discovered in 1930 by the astronomer Clyde Tombaugh, turns out to be the first known example of a new class of planetary bodies called ice dwarfs — the third class of planets: where the Earth, Mercury, Venus and Mars are rocky worlds, and Jupiter, Saturn, Uranus and Neptune are gas giants The ice dwarfs are believed to be embryo planets, formed in the early days of the solar system more than four billion years ago. While other planets went on to bigger things, the ice dwarfs stopped growing.

As well as being the furthest planet from the Sun although its orbit means it is sometimes closer than Neptune — Pluto is the oddball of the solar system.

Pluto also has a less circular orbit than the other planets, it orbits around its poles instead of its equator — a characteristic it shares with Uranus — and is orbiting on a tilt of 17 degrees, more than twice as great as the next highest, Mercury, which tilts at seven degrees.

Pluto is also one of only four objects in the solar system to possess a mainly nitrogen atmosphere, the others being Saturn’s moon Titan, Neptune’s moon Triton, and the Earth. Although its surface is about minus 223 degrees Centigrade, scientists believe its interior may be warm enough to house an ocean.

The surface of Pluto is roughly minus 223 degrees Centigrade. Pressure on the surface is between three and 100 millionths that on Earth, and if you stood on Pluto you would weigh approximately seven per cent of your weight on Earth.

Pluto orbits the Sun every 248 years, and turns on its own axis once every six and a half days. During daylight on Pluto, the Sun would appear almost 300 times as bright as the full moon on Earth, but 900 times dimmer than full daylight on Earth.

Pluto’s moon Charon was discovered in 1978. Charon is more than half the size of Pluto, leading to some suggestions that they are in fact binary planets, revolving around a point between them. Two further satellites were discovered late last year. Pluto is the only planet whose rotation is synchronized with its satellite, meaning Pluto and Charon continuously face each other.

Pluto is hundreds of times fainter than can be seen with the naked eye, but can be seen with an amateur telescope — as long as you know where to look and observe the sky over several days.

posted by: kyawoo at 20:38 | link | comments |
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