By David Ward
On a clear, dark October evening you can still see the Milky Way stretching across the sky from northeast to southwest. Look for a pale, glowing band of light and, if you see it, you have spotted the galaxy in which we live, our home in the vast cosmos. Our sun is one of several hundred billion in this immense conglomeration. It is difficult for us to imagine how large the Milky Way galaxy really is. Astronomers tell us it is 100,000 light years across, but that does not begin to convey the enormous size of that glow of light in the sky.
The space probe Voyager 1 is the farthest man-made object from Earth. Launched in 1977 and traveling at a speed of 35,500 miles per hour, it is currently about 12,276,000,000 miles from Earth. In another 80,000 years, the probe will be at about the same distance as the nearest star other than the sun. That is a start on a journey across the galaxy, but not much of one, because in 80,000 years Voyager 1 will only have completed one part in 25,000 of the vast distance across our galaxy. What all this means is that our galaxy is really, really big and that our favorite science fiction characters like Captain Kirk and Mr. Spock, who hopped from star to star like they were running errands on their way home from work, were going really fast.
But wait, there is something else out there that is even bigger. With a little patience and a dark, clear night away from distracting lights, you, too, may be able to see it. It will not be easy because it is a long ways away and it is quite dim, but those of us who are blessed with the dark skies of the Methow Valley have a shot at it.
Go outside and give your eyes a few minutes to adjust to the dark first. That way they will be sensitized to see the dimmest objects up there. Then find the constellation Cassiopeia up in the northeast. It looks like the letter “W” on its side. Notice that one of the points of the W is sharper than the other. Early in the evening that is the upper point. Use it to point to the southeast about one length of Cassiopeia. Look for a pale, oblong, fuzzy spot in the sky. Cannot find it? Try again using binoculars. It will stand out a lot better.
What is that fuzzy-looking thing anyway? It is another galaxy, called Andromeda, and it is the biggest one in our corner of the cosmos. No one is sure exactly how big it is, but it is probably about twice the size of our own Milky Way. If you do manage to see it, you can be sure that it is the most gigantic thing you have ever seen.
Remember all that nonsense in science fiction stories about “tractor beams?” Han Solo’s space ship got sucked into the evil Death Star by one in the first Star Wars movie. Maybe you thought, like I did, that it was pretty foolish. Actually, it is all real and it is called gravity. The Andromeda galaxy, being a lot bigger than our galaxy, has a lot more gravity and it is sucking us in like a giant tractor beam. Another way to look at it is that we are falling into Andromeda at over 1 million miles per hour and there is nothing anyone can do about it. Do not worry, you do not have to rush out and buy collision insurance tomorrow. It will be a while before we get there, like several billion years.
You may wonder if we are falling so fast why it will take so long to get there. But I bet you guessed that it is a long ways away. The Voyager 1 would take about 50 billion years to make the trip. That is a time span far longer than the age of the universe. What all this means is that little fuzzy spot is not only the biggest but also the most distant thing you have ever seen.
Early in the evening you may still catch a glimpse of Saturn low in the southwest. That is the star Antares, the heart of the scorpion, to the left. The brightest planets are seen in the early morning just before sunrise. Look for dazzling Venus high in the east. You cannot miss it. Lower and a little bit to the left, not-so-bright Jupiter is pretty easy to pick out. Between the two, much dimmer Mars is more difficult to spot in the brightening twilight.
Remember Captain Kirk calling down to chief engineer Scotty to rev up the Enterprise to warp 10 because they had to get there before those nasty Klingons? Warp 10 is 10 times the speed of light and I wonder how feasible it is to go that fast. Albert Einstein told us that the speed of light is the speed limit in this universe. Nobody, nothing, nohow is going to travel through space faster than that. Recently two physicists, Yurtsever and Wilkinson, have calculated what would happen if a space ship traveling at almost the speed of light ran into a speck of dust floating around out there. The impact would be so catastrophic that it would be like the explosion of 5,000 pounds of dynamite, Think about that the next time you are watching old Star Trek reruns.