Ask Dr. SETI ®
by Dan Duda
from the April, 2022 issue of Penn Central,
the monthly newsletter of Central PA Mensa,
used by permission
Good Grief! Think of all the mass; the power; the velocity. When our Milky Way collides with the Andromeda Galaxy, calling it a cosmic event just doesn’t do it justice. Our Milky Way has 100 thousand million stars, our Sun being just one. Andromeda has over a trillion. And, these behemoths are racing toward each other like WWF wrestlers with fire in their eyes. But don’t get the bomb shelters ready just yet – it isn’t scheduled to occur for another 25 million years.
Interestingly, the Andromeda occupies a visual area in our sky larger than the Moon. But, we can’t see it with our naked eyes, because at the current distance and the spread of its stars, not enough light is reaching us yet. However, we can see several of its stars, including (Alpheratz) Alpha Andromedae, which is a binary and part of the Pegasus constellation.
Now maybe back to the call for bomb shelters. Cosmologists are learning more about the universe every day. And one of the more recent ideas is that there is more to galaxies than previously thought. More specifically, invisible matter seems to expand the radii significantly further than our classic measurements have told us. OK, wait for it. That means the collision may already be occurring!
Don’t worry, the need for bomb shelters still isn’t called for. It will take about 25 million years for us to see any effect of the merger. And even at the peak of the collision, any danger will be at a minimum for at least two major reasons:
What may happen as the pileup progresses is an ejection of our solar system into the void. That wouldn’t necessarily disrupt Earth’s orbit around the Sun. And ,the emerging view of the chaos we would be leaving would likely be breathtaking (too bad we won’t be there to see it.)
When you’re wondering what happens when two galaxies collide, try not to think of objects smashing into each other or violent crashes. Instead, as galaxies collide, new stars are formed as gasses combine, both galaxies lose their shape, and the two galaxies create a new supergalaxy that is elliptical.
It's also interesting to note that collisions are not new to the Milky Way. Not only have we consumed several smaller galaxies, but that process is occurring right now. For example, the Sagittarius Dwarf Spherical Galaxy is joining our party. A stream of its stars is leading the way. The small and large Magellanic Clouds are also patiently waiting their turn.
A quote by Carl Sagan seems appropriate here. “The near side of a galaxy is tens of thousands of light years closer to us than the far side; thus, we see the front as it was tens of thousands of years before the back.”
And, in the words of Neil deGrasse Tyson “We are part of this universe: we are in this universe, but perhaps more important than both of those facts, is that the universe is in us.” And of course, the Milky Way is in the universe.
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this page last updated 7 May 2022
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