On a clear day it looks like you can see forever, but on a clear night you can see even farther. Last month I guided you towards the Milky Way galaxy, which is probably the biggest and the most distant object you have ever seen. This month let’s take it up a notch and look for something even bigger and really far out there.
Use the constellation Cassiopeia, which is shaped like a W with two points, to find a hazy little fuzz ball up in the night sky. If I am not there with my laser pointer, then you might need a star chart. If the sky is still smoky, forget it for now and wait until the smoke clears.
If you manage to see it, congratulations. It is the biggest and the farthest away object you have ever seen. What is it? That fuzzy little thing is photons, quadrillions of photons, created in the core of stars in another galaxy.
They have been traveling at the amazing speed of light for a staggering 2,500,000 years just to reach your eyeballs and say hello. They call it Andromeda.
It is huge. Our own galaxy, the Milky Way, has 300,000,000,000 stars in it. That is a big number, but Andromeda has twice that many,
Standing out there looking at Andromeda, let go of your perspective of what is up and what is down. Try to imagine that you are looking downhill in the biggest sense of the word. That distant galaxy has more stars, a lot more. That means more mass, and more mass means more gravity. That means we are falling into Andromeda at a speed of 1,300,000, miles an hour. There is good news and bad news about all of this.
The bad news first. We are going to crash. There is nothing anybody can do to prevent it.
Eons to go
The good news. You do not have to rush out and buy collision insurance tomorrow. It will be awhile before we get there.
I know it is confusing trying to picture galaxies careening through space on a collision course each with hundreds of billions of stars inside. Here is a simple demonstration you can do in the comfort of your living room. Amaze your family and friends with your knowledge of celestial mechanics.
Get two footballs and paint an A on one for Andromeda and a MW on the other for Milky Way. Place them on your living room floor 30 feet apart. Interestingly, enough this is the scale of the size and distance between the two galaxies. Now all you have to do is sit down on your couch and watch carefully. In 11,111,111 years the two galaxies will move one inch closer together. And that is gravity at work, the same force that lets you collapse in your easy chair after a hard day of working in your yard.
Closer to home, this is a great time to watch Venus transition from the Evening Star to the Morning Star. She is getting lower in the west just after sunset. If you have a small telescope, watch her change into a beautiful thin crescent. Later in the fall, you can spot her low in the east at dawn.
I know this whole thing about the Andromeda Galaxy sounds dire, but I do not worry. I do not think any of us will live to see it.
