Observing the Cosmic Ladder - The Andromeda Galaxy
Moving beyond the boundaries of our own Milky Way galaxy, the next major celestial landmark we encounter is the Andromeda Galaxy, 2.5 million light-years from Earth. Best of all, it can be viewed from Earth on a clear night with the unaided eye, as it’s roughly four times wider than the disc of the full Moon.
As it continues to move into the evening sky we’ll post more tips and details for locating it, if you’d like to give it a try now you can spot it after midnight in the eastern sky (you can use any freely available planetarium program to help navigate).
The Andromeda Galaxy is similar to our own Milky Way in many regards, though it is believed to be more massive. Perhaps most interesting to us Earthlings is that we’re headed straight on a collision course toward the Andromeda Galaxy, though not for another 4.5 billion years, so no cause for alarm yet! Curiously, physicists have discovered that when galaxies merge their stars don’t appear to collide with each other, a phenomenon still being studied.
Here’s a clip produced by NASA discussing more about the Andromeda Galaxy:
Galactic collisions are not rare, believe it or not. In fact we have numerous collisions that are visible from Earth right now and being studied. There’s no hurry either, these collisions happen over an era of cosmological time at an almost incomprehensibly glacial pace, so we won’t see motion as we observe. What scientists instead look at are the different stages of collision, as determined by a galaxy’s age, and compare observations to predictions based on a continuously growing understanding of collision dynamics.
Furthermore, we’re quite literally peering back through time to witness these colossal structures interact with each other. Because of the staggering distances involved, the light that is currently reaching Earth is from the ancient past, (remember the Andromeda Galaxy is 2.5 million light-years away, and it’s relatively close!) the galaxies today may not look anything like what we see today, a lot can change in a million years!
Here’s an article with pictures and further discussion of galaxy collisions:
Join us Wednesday 9/2 @ 6:00 PM for another virtual event on the space program “Apollo: Getting Home.” Email LBmartin@cityofwestminster.us to register for this free virtual program.
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