No place like home

The European Space Agency’s Rosetta mission snapped this stunning picture of a crescent Earth during a Nov. 13, 2009, flyby of our planet. This was the final Earth flyby on the craft’s journey to its ultimate destination: Comet 67P/Churyumov-Gerasimenko. Credit: ESA/OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA/Gordan Ugarković

At the end of the classic 1939 film The Wizard of Oz, after defeating the Wicked Witch of the West, Dorothy Gale squeezes her eyes tightly shut, clicks the heels of her ruby slippers together, and whispers, “There’s no place like home.” And she was right.

Eighty-seven years after cinema audiences were thrilled by that restless Kansas girl’s adventures, we know we live in a spectacular solar system full of wondrous worlds wheeling around a golden Sun. Venus blazes like burning magnesium in our sky, but is a hell planet beneath a deadly atmosphere. Mars, although half Earth’s size, has volcanoes and canyons that dwarf the largest of our own. Jupiter is a bloated ball of gas so huge it could swallow Earth a thousand times over and still have room for more. And Saturn is surrounded by a system of rings that shine in our telescope eyepieces like icy hoops.