Nine Of The Most Surprising Facts About Andromeda Galaxy

The closest large galaxy to us, the Andromeda galaxy, is one of the very few galaxies which can be seen with the naked eye from Earth. It is much bigger than the Milky Way, but apparently, it is similar in mass.

The Andromeda galaxy is an elliptical type of galaxy, and it is the largest galaxy in the Local Group – a conglomeration of galaxies of which our own Milky Way is part of.

Apart from these statements, what makes the Andromeda galaxy so unique? Well, there is a lot more than that, here are some awesome facts that you may or may not know about the Andromeda galaxy.

Andromeda Galaxy
Credit: NASA

1. The Andromeda Galaxy has around four times as much stars as the Milky Way

Estimates suggest that Andromeda has around 1 trillion stars; in comparison, our Milky Way only has between 200 to 400 billion stars. NASA’s Hubble Space Telescope has uncovered a large and rare population of scorching, bright stars as a part of those one trillion.

These blue stars have cast out their outer layer of materials and exposed their blue-hot cores. They are scattered throughout the galaxy’s center and are the brightest in ultraviolet light.

Curious to know more about Hubble Space Telescope? Check Top Features and Discoveries of Hubble Space Telescope

Andromeda Galaxy size
Credit: NASA

2. Andromeda has a double nucleus

There are two points of light-peaks situated in the center of Andromeda. They contain millions of densely packed stars, and about five light-years separate the ends.

The first point is designated as P1, while the second P2. Some scientists determined that the nucleus isn’t really composed out of two pieces but preferably just one lopsided group of stars that are orbiting a supermassive black hole.

The stars in the P1 point follow elliptical orbits around the black hole, and they mostly shine in the outer regions, making the area very bright. The second nucleus only exists since the stars bunch together when approaching the black hole.

Andromeda Galaxy double nucleus
Credit: NASA

3. The Andromeda galaxy will clash with our Milky Way

The Andromeda galaxy is set on a collision course with our own galaxy, the Milky Way. It is heading towards us at around 400,000 km/h (248000 mph). With such a velocity, one could circle the Earth in just six minutes.

Astronomers estimated that this collision will take place somewhere around 3.75 billion years from now. But will the Earth survive this collision? Scientists strongly believe that it will [1].

Our planet will mostly be unharmed since galaxies are made up of mostly empty space. The collision will be seen throughout the sky for many years as the two galaxies continue to tug each other for long periods until their central black holes merge as well.

To discover more, check 16 Mind-Blowing Space Facts You Should Know

Andromeda and Milky Way Galaxies
Credit: NASA

Once this process is over, our solar system will be in an entirely different type of galaxy known as an elliptical galaxy.

Andromeda and Milky Way Galaxy collision
Credit: NASA

4. Andromeda galaxy has more black holes than we could count

The Andromeda galaxy is swarming with black holes, and astronomers have found even newly formed black holes. Most of them have between five to ten times the mass of our Sun.

Close to the galaxies center, many of these newly formed black holes were found at around 1,000 light-years away. However, there are two supermassive black holes located in Andromeda’s center; they are the closest-orbiting pair currently documented.

Scientists speculate that they could collide within less than 350 years and merge as one larger black hole. Both black holes are around 0.01 light-years apart, which is just a few hundred times the distance of the Earth from the Sun.

You can discover more about black holes’ mystery in the following article: 9 Of The Most Surprising Facts About The Black Holes

Andromeda Galaxy black holesa
Credit: NASA

5. The Andromeda galaxy is filled with globular clusters

These clusters are densely packed collections of ancient stars, and they contain hundreds of thousands or even millions of stars. They are used in determining the age of the Universe, or they can be used to pinpoint galaxies center.

Scientists have identified over 200 globular clusters in the Milky Way, but around 450 have been observed in the Andromeda galaxy. These numbers can be even higher for Andromeda since the outermost of its regions haven’t been researched enough.

If these clusters would have the same range and size as those in the Milky Way, then Andromeda could have anywhere between 700 to 2,800 globular clusters.

Andromeda Galaxy globular clusters
Credit: NASA

6. The Andromeda galaxy was thought to be a nebula in the beginning

Nebulas are massive clouds of gas, dust, hydrogen, helium, and plasma, and they are regions where stars are born. Since we began to analyze the heavens more seriously, galaxies were often mistaken for nebulas.

It was thought that the Milky Way was the only galaxy in the Universe, surrounded by nebulas. This changed in 1924 when astronomer Edwin Hubble announced that Andromeda was actually a galaxy and not a nebula.

Andromeda Galaxy
Credit: NASA

Through his works, many other galaxies were found, but mainly, the conclusion that Andromeda was another galaxy completely changed our perspective of the Universe.

Hubble found many stars in the Andromeda galaxy, including the famous Cepheid variable type of stars. They are used to measure the distance between celestial objects. Using these stars, he concluded that Andromeda was 860,000 light-years away from us. However, it is actually 2.5 million light-years away.

7. Andromeda is also known as Messier 31

The famous French astronomer, Charles Messier, cataloged Andromeda and many other celestial objects in the Northern Hemisphere. They are collectively known as the Messier objects.

In 1757, Messier began the hunt for Halley’s comet, but the calculations given to him had sent him to a different section of the sky. He observed there a nebula that became the first entry in his catalog, M1, also known as the Crab nebula.

Messier 31 Galaxy
Credit: NASA

In 1764, he added M31 to his catalog, and by 1781 he logged a total of 103 objects, 40 of which had been discovered by Messier himself.  Since the galaxy is located in the constellation of Andromeda, it borrowed the same name [2].

The constellation was catalogued by the Greek astronomer Ptolemy in the second century BCE. Andromeda was the wife of the Greek hero Perseus.

8. It is larger than the Milky Way

Our Milky Way measures around 100,000 light-years or 30 kiloparsecs. In comparison, the Andromeda galaxy has a diameter of about 220,000 light-years; thus, it is more than twice as large as the Milky Way.

Though it is far away from us, if it were a bit more bright, the Andromeda galaxy would appear more significant than our Moon in the night sky. It has an apparent magnitude of 3.4, the brightest of any Messier objects.

It appears around six times wider than the Moon in the sky, though given its distance, and the Moon closeness to us, one can imagine the scale of Andromeda.

9. Andromeda and the Milky Way are part of the Local Group

Though Andromeda is twice the size of the Milky Way, its mass isn’t significantly bigger. This suggests that our own galaxy may have more dark matter than Andromeda.

Both the Milky Way and Andromeda are part of the Local Group, a conglomeration of 50 other galaxies, which are gravitationally bound to one another.

The majority of these galaxies are dwarf galaxies, which are orbiting the three largest: Andromeda, the Milky Way, and Triangulum. Though Andromeda is the largest galaxy in this group, it is unknown if it is also the most massive.

To discover more about the universe beginning, check What is the Big Bang, and how did the Universe Begin?

The Local Group of galaxies
Credit: NASA

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