This is the Astronomers Alphabet. Today we start with the letter “A.” “A” stands for “Astronomy,” of course, the study of the stars, moon and planets, of the sky, of the entire universe for that matter, including the earth, which is very much a part of this great cosmos. “A” stands for “Astronomer,” someone who studies everything and yet is limited unlike other scientists who can touch the things they study: we can see the stars, we can reach for the stars, but we can never touch them. “A” is for “accretion discs,” great whirlpools of gas and dust that surround forming solar systems, dying novas, and of course, weird black holes. “A” is for astronaut, someone who travels into space, and while aboard the International Space Station, orbits the earth every 90 minutes. And “A” is also “Andromeda,” both a constellation in the heavens and a great spiral galaxy that lies beyond our Milky Way, two and a half million light years out.