火星快车号传来的火星南极冰盖图像 Mars Express image of the icy cap at Mars’ south pole (© ESA/DLR/FU Berlin/Bill Dunford)

火星快车号传来的火星南极冰盖图像 Mars Express image of the icy cap at Mars’ south pole (© ESA/DLR/FU Berlin/Bill Dunford)

An ice cap-puccino

No, that's not a new frozen coffee drink from Starbucks; it's the southern polar ice cap on Mars. Mars is the only other planet in the Solar System with a visible ice cap, though it differs from Earth’s because it is comprised of both water ice and frozen carbon dioxide. The ice cap looks smooth here, but its surface is pockmarked with swiss cheese-like depressions caused by the seasonal freezing and melting of the Martian winters and summers. While Mars has been observed by humanity for thousands of years, it was only on August 13, 1642, that Dutch astronomer Christiaan Huygens observed the ice cap using the most powerful telescope of the day. The giant of science designed the 50x magnification telescope himself, and with his brother, produced the lenses as well.