By David Ward
A brisk fall evening is the perfect time to catch a glimpse of the Milky Way. Go out on a moonless night away from distracting lights and look for a glowing band of light stretching across the sky from northeast to southwest. That is our home in the vast cosmos, a huge pinwheel-shaped structure called a galaxy containing several hundred billion stars.
Our sun is one rather unremarkable inhabitant of the Milky Way galaxy except for our amazing little planet we call Earth circling around it. Here, due to an amazing stretch of “good weather” that has lasted for several billion years, what we call life has developed consciousness and is able to look out at the universe and understand what it sees.
How many other planets orbiting the billions of stars in our galaxy are this lucky? That is a question hotly debated among astronomers, but probably very few.
Look low in the southwest near the end of the Milky Way for a group of stars shining in the glow. That is Sagittarius, the archer. It does not get very high in the sky as seen from this latitude. The sun is hanging out there at the winter solstice, which is why the sun is so low in the sky in the winter.
The constellation Sagittarius is associated with Chiron, a half-horse, half-man creature known as a Centaur. Centaurs were a rowdy and unpredictable bunch who crashed around in the forest causing trouble. You really would not want to be caught unawares and alone with those characters.
Chiron, however, was different. He could predict the future and could read the fortunes of men in the stars. He was also known as a wise teacher and instructed such notable pupils as the great Greek warrior Achilles and Aeneas, the Trojan who escaped the destruction of his city and founded Rome.
One thing extraordinary about Sagittarius is that the center of the Milky Way Galaxy resides in the dim glow behind those stars, the center of everything within 100,000 light years. How far is that? Trust me, a long, long way, farther than we can imagine.
A new planet?
Chiron would have been proud to know that the center of the galaxy resided in his part of the sky. Back in his day no one had a clue what the Milky Way actually was. Legend had it that it was some kind of a celestial river or even breast milk from the Greek goddess Hera, wife of Zeus. Our name for our galaxy comes from that old legend.
See if you can spot reddish Mars and yellowish Saturn low in the southwest to the right of Sagittarius. They are not going to be with us much longer as they are drifting into the sunset glow. If you are somewhere where you can see very low into the west, you might be able to see the planet Venus just after sunset before it gets dark. Venus has been residing in the east as the morning star for the past year, but will dazzle us with her beauty in the evening this fall and winter.
Probably you have heard about a new planet astronomers have found circling the star Proxima Centauri, the closest star to us besides our sun. This news is very exciting and I wish I could tell you where to look for it. Unfortunately, it is located in that region of the sky visible only from the southern hemisphere or much closer to the equator than we are.
Also, that star is very dim and even though it is “close” to us, it is invisible to the naked eye. The new planet is in the habitable zone of its star meaning that water could possibly be in the liquid state there. We do not know if the planet has water or not. Using our current technology it would take us about 75,000 years to get there, so it might be a while before we know all the answers about our new next-door neighbor.