Dwarf Planets Ceres and Eris

With the discovery of Pluto in 1930, most astronomers considered the Solar System to have nine planets, along with thousands of significantly smaller bodies (asteroids and comets). For almost 50 years Pluto was thought to be larger than Mercury, but with the discovery in 1978 of Pluto’s moon Charon, it became possible to measure Pluto’s mass accurately and to determine that it was much smaller than initial estimates. It was roughly one-twentieth the mass of Mercury, which made Pluto by far the smallest planet. Although it was still more than ten times as massive as the largest object in the asteroid belt, Ceres, it had one-fifth the mass of Earth’s Moon. Furthermore, having some unusual characteristics, such as large orbital eccentricity and a high orbital inclination, it became evident that it was a different kind of body from any of the other planets.


As expected, coming in a range of materials means that there is extensive flexibility with respect to colour choice. Throughout their history the Moon Boot has always been a bright and happy addition to any winter wardrobe and now is no different. Colour examples include neutral and subtle tones such as ochre, grey, dark brown, black and ice through to light pink, violet, azure, petrol blue, orange and sea green. More conspicuous colours consist of silver, ivory, burgundy, bouganville, apricot, red and yellow especially since some also come in a metallic finish. As time passed, the region would have cooled down considerably and contracted--thus pulling away from its surroundings and forming fractures akin to the cracks that form in mud as it becomes dry--but on a considerably larger scale. "The rectangular pattern of gravity anomalies was completely unexpected. Using the gradients in the gravity data to reveal the rectangular pattern of anomalies, we can now clearly and completely see structures that were only hinted at by surface observations," Dr. Jeffrey Andrews-Hanna explained in the October 1, 2014 NASA Press Release. Dr. Andrews-Hanna, a GRAIL co-investigator at the Colorado School of Mines in Golden, Colorado, is lead author of the paper.