Dwarf Planets : Pluto
The never-before-seen surface of the distant planet Pluto is resolved in this NASA Hubble Space Telescope picture, taken with the European Space Agency's (ESA) Faint Object Camera (FOC) aboard Hubble.
Discovered in 1930, Pluto has always appeared as nothing more than a dot of light in even the largest Earth-based telescopes because Pluto's disk is much smaller than can be resolved from beneath the Earth's turbulent atmosphere. Pluto is 2/3 the size of Earth's Moon but 12,000 times farther away. Hubble imaged nearly the entire surface of Pluto, as it rotated through its 6.4-day period, in late June and early July 1994. These images, which were made in blue light, show that Pluto is an unusually complex object, with more large-scale contrast than any planet, except Earth.
Some of the variations across Pluto's surface may be caused by topographic features such as basins, or fresh impact craters. Most of the surface features unveiled by Hubble, including the prominent northern polar cap, are likely produced by the complex distribution of frosts that migrate across Pluto's surface. The original picture was taken in blue light when Pluto was at a distance of 3 billion miles from Earth.
In August 2006 the International Astronomical Union voted on a new definition for planet and Pluto did not make the cut. Rather, Pluto was re-classified as a dwarf planet and is considered as a prototype for a new category of trans-Neptunian objects.
Image : Alan Stern (SRI) Marc Buie (Lowell) NASA ESA
