The Andromeda galaxy is a galaxy that’s pretty close to ours, but it’s bigger, with a truly insane star mass.
The Andromeda galaxy is named after its resemblance to a female figure in Greek mythology.
Andromeda is the largest galaxy in its cluster, a cluster that our own galaxy the ‘Milky Way’ is a part of.
There are over 1 trillion stars in this galaxy and what else? What else? Oh yeah, it eats other galaxies!
Yeah, you read that right. Andromeda is a cannibal galaxy that has been eating up other galaxies since it was a wee one.
While we have no idea just how far back this goes, scientists believe that Andromeda started consuming galaxies when it was young.
What Exactly Is Galactic Cannibalism Anyway?
Put simply, galactic cannibalism happens when galaxies of different sizes collide, and the smaller of the two becomes trapped within the larger, adding to its overall mass.
Andromeda’s Rumblin’ Tum
Andromeda’s appetite for other galaxies grew as it devoured smaller galaxies, eventually growing into the massive and beautiful thing it is today.
So although it looks more or less like a star field (which it is), all those black dots aren’t actually individual stars; they’re just little pieces of other galaxies that the Andromeda galaxy gobbled down years ago.
And unlike us, Andromeda has lots of room to grow because there’s plenty of space between the rest of the Milky Way galaxy.
As mentioned earlier, we don’t really have a full account of Andromeda’s cannibalistic past, but we know for sure that it has devoured at least two significant galaxies.
The first of these galaxies (Andromeda’s starter course) was consumed between 7 and 10 billion years ago, and the second, (the entrée), in the last few billion years, and now we may be for dessert!
The Andromeda galaxy is currently being pulled towards our own by a vast amount of dark matter that surrounds it.
This can be seen if you look at the constellation Ursa Major which contains many stars near where the Andromeda galaxy once resided before it moved away from Earth.
Even though the distance between the Milky Way and Andromeda has increased dramatically over time, both galaxies are still bound together by powerful gravity.
The Andromeda galaxy is headed for a collision with our own. Both galaxies will collide around 4 billion years from now.
By then, our Milky Way Galaxy may not even exist anymore!
Scientists estimate that the galaxies closest to Andromeda will fly past us on average once every 40 million years.
But don’t worry: none of these near-misses will affect life here on Earth.
Our home will be okay as long as we manage to avoid a direct hit.
If our planet was ever threatened by a close encounter with another galaxy, astronomers would likely send out probes to attempt to find habitable planets orbiting nearby stars.
These distant worlds could provide clues to whether intelligent life exists elsewhere in the universe.
More good news… kind of — in 5 billion(ish) years, when the collision between our own galaxy and Andromeda is set to occur, the temperature on Earth will have increased to the point where no liquid water will exist on the planet.
This means that all life as we know it will have perished, so even if something were to go incredibly wrong during the collision, we wouldn’t be around to witness it.
Weirdness From Andromeda
In some cases, the Andromeda galaxy doesn’t only gobble up entire galaxies but also makes them explode.
This occurs when the Andromeda galaxy slams into a small galaxy causing an explosion.
These explosions occur when a large quantity of matter collides with a smaller quantity resulting in gravitational forces exceeding those necessary to maintain equilibrium.
Because there is very little mass left behind, the leftover material forms a highly energetic blast.
When this happens, it emits more energy than any nuclear bomb you’ve ever heard of.
In fact, sometimes there are so many supernovae going off at once in Andromeda that they create huge amounts of radiation detectable throughout the electromagnetic spectrum.
Some supernovae emit too much light for the human eye to detect, however.
It takes telescopes equipped with sophisticated cameras and spectrographs to see these events.
There is one peculiar type of supernova known to happen in Andromeda that is thought to be unique to it.
Called hypervelocity stars, these are believed to result when a star born within the Andromeda galaxy gets ejected from its planetary system early in its evolution.
This usually happens when a giant gas cloud collapses under its own weight and begins to form a new star.
The newly formed star quickly becomes unstable, throwing off huge quantities of stellar debris.
If the ejected star travels fast enough, it can escape the gravitational pull of the parent galaxy.
Hypervelocity stars have been observed leaving Andromeda.
They travel faster than most stars and appear to come from the far side of the galaxy.
In fact, scientists believe that they came from a dwarf galaxy that was swallowed up by Andromeda billions of years ago.
Is Andromeda A Threat To Earth?
This particular type of supernova is interesting because it could help explain why Andromeda appears to be moving closer to the Milky Way.
A recent study suggests that the Milky Way and Andromeda are slowly drifting closer due to their mutual gravitational attraction.
This means that if Andromeda has been eating other galaxies, it might eventually devour the Milky Way.
However, the authors of the study say that this scenario is unlikely.
Instead, they think that Andromeda is simply approaching the Milky Way on a more gradual basis.
The researchers used computer simulations to model how the two galaxies move toward each other over time.
Their results suggest that Andromeda will pass through the Milky Way about four billion years from now.
At that point, the two galaxies will begin to merge. During the merger, both galaxies will produce lots of tidal tails of stars, gas, and dust.
Eventually, all of this material will fall back onto the central region of the merged galaxy forming a single disk.
Scientists predict that the combined mass of the two galaxies will increase by about 1% during the next few billion years.
This means that the total gravity acting upon our solar system will increase slightly.
As a result, the orbits of planets like Mercury and Venus will become less stable.
This could cause the inner planets to be flung out of orbit or even pulled into the Sun.
If this were to happen, It’s possible that Earth would be no more. Fortunately, astronomers aren’t worried about this happening.
They say that the chances of such a catastrophe occurring are extremely low.
They estimate that the probability of this event occurring is no greater than 0.1%.
What Is Andromeda Made Up Of?
It turns out that Andromeda isn’t just full of stars, but also full of planets.
Astronomers have discovered thousands of exoplanets orbiting stars in the Andromeda Galaxy.
And since all of these planets are located relatively close to their host stars, they are considered “hot Jupiters”.
Hot Jupiters are Jupiter sized planets that orbit very closely to their stars. As such, they experience extremely high temperatures.
For example, Mercury experiences surface temperatures of about 800 degrees Fahrenheit (427 degrees Celsius).
On the other hand, hot Jupiters like Kepler 45b experience surface temperatures of over 3200 degrees Fahrenheit (1680 degrees Celsius) which is almost as hot as the surface of the sun!
Since hot Jupiters are so close to their host stars they receive a lot of heat.
This causes them to lose a significant amount of atmosphere through evaporation.
Over time, the planet loses its ability to retain water. Eventually, the planet becomes completely dry.
If the Andromeda Galaxy were to consume the Milky Way, it would likely swallow the solar system along with it.
However, astronomers aren’t sure exactly what will happen next. Will the Milky Way survive? Or will Andromeda devour us?
Only time will tell.
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