M31, or how I learned to stop worrying and love 700 billion stars

There are quite a few galaxies out there. Ironic as it may be, it’s far easier for us to get a good look at pretty much any one of them than it is for us to see our own. Being in the middle (but not at the center, that would be bad) of our fabulous Milky Way makes anything on the far side of our central bulge virtually impossible to examine. It’s like trying to understand the dimensions of a forest while surrounded by trees, there’s only so far you can look in most directions.

Pretty much all the “close” galaxies require at least binoculars or a small telescope to view, the distant ones require A LOT more. There’s one, however, that you can see with your naked eye, even in a somewhat light polluted area. I live within Boston city limits (though on the outskirts) and on a clear night, I can see it from my back yard, just by looking up. The one, the only, Andromeda Galaxy.

It's slightly less impressive when you see it bare-eyed, FYI.

To the un-aided eye, it looks like a fuzzy patch, but an entire galaxy is what you’re looking at. Weighing in at about 700 billion solar masses (our sun=1 solar mass), this is a BIG galaxy. We can see it with relative ease because it’s 220,000 light years wide. The Milky Way is no chump, but this thing is a monster. It’s no Abell 2029 mind you, at least, not yet. There will come a day when it grows much larger, and we (residents of the Milky Way) are going to be a big part of it, and I don’t mean that figuratively.

In about 2.5 billion years it’ll be our new home, that is, once it has consumed the Milky Way. It’s headed this way, right now, at 300 kilometers per second. Fortunately for our immediate plans, its distance of 2.5 million light years will ensure it arrives fashionably late. By then our sun’s energy output will have gone up by 20% and will have long since evaporated our oceans and raised Earth’s mean surface temperature to something much like what Venus has now, thanks to all that evaporated ocean in our atmosphere. We’ll have either left for greener pastures or come up with some clever way to keep things cool long, long before any of this becomes an issue. If our descendants are still hanging around though, provided they still have heads with eyes, they’ll have one heck of a view when they look upat the night sky. Of course, we may evolve into eyeless mole people by then. There’s no doubt that we’ll be unrecognizably different that far out, should we endure. I’d say we probably have a 50/50 shot of avoiding moleification, but I digress.

Personally, I think this is a pretty bad ass thing to see, even for us 21st century humans that almost always have heads with eyes. Get some binoculars or a scope and it’s even more so! Either way, we have some clear nights coming and this will be high in the sky, just waiting for you. Currently, you’ll find it if you look straight up around midnight. How easy is that?

BUT WAIT! THERE’S MORE!!! If you act now (or at any point in your lifetime), you’ll also get to see M32 ABSOLUTELY FREE!

M32 is the dwarf galaxy that acts like a satellite around M31, which provides some additional influence on the larger galaxy’s star formation. The Milky Way has a couple of these as well, and some day, we’ll all be one big happy family. Well, all our stars will be part of the same greater object anyway. We’ll have to leave the happiness part to the mole people.

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