General, Research, Technology

The collision between Andromeda and the Milky Way has already begun. Why so early?

In about 4 billion years Andromeda Galaxy will finally collide with our galaxyMilky Way, which will lead to a bright flash and, according to scientists, the formation of a new galaxy. This is not news - astronomers learned about the impending collision in the last century, it was discussed in many popular books, and the team working with the Hubble Space Telescope even made beautiful illustrations of what the impending explosion would look like. But this story has an unexpected twist. Earlier this week, researchers working on a sky mapping project called AMIGA reported that the first stages of a collision between Andromeda and the Milky Way will occur much earlier. Looking up to the night sky, you can see it ... because the collision of Andromeda and the Milky Way already started.

If Andromeda was highlighted enough, you would see her on Earth now.


  • 1 Collision of the Milky Way with the Andromeda galaxy
  • 2 What does the Andromeda galaxy look like?
  • 3 How to see another galaxy?
  • 4 What will happen to the Earth after the collision of galaxies?

Collision of the Milky Way with the Andromeda galaxy

The reason why the collision occurs onseveral billion years ahead of schedule, is that the Andromeda galaxy is much larger than it seems. The bright stellar disk of this galaxy is about 120,000 light years across, slightly larger than the Milky Way. In recent years, exploration of Andromeda using giant telescopes has revealed a large population of stars, resulting in an overall diameter increase of about 200,000 light years... However, this is nothing compared to the latest research.

Nicholas Lehner of the University of Notre Dame and hiscolleagues have determined that Andromeda's halo - its outer shell of thin hot gas, similar to the "galactic atmosphere" - is located 2 million light years from its center. The AMIGA project team also revealed that the shell is split into two layers: the inner one, where supernova explosions rage, and the outer one, which is much quieter.

The Milky Way Galaxy is very similar to Andromedain size and structure, this became known not so long ago. This means that the halo of the Milky Way is similar to that of Andromeda. Andromeda is 2.5 million light-years from the Milky Way. And if each of these galaxies has a halo stretching for 1-2 million light years in all directions, then their contact has already begun.

What does the Andromeda galaxy look like?

If you could take a full view of the galaxyAndromeda, it would seem incredibly large in the sky. The disk of the galaxy is visible to the naked eye as a fuzzy spot about half the width of our Moon. Long exposure images taken with telescopes show faint outer spiral arms that increase significantly in size.

But the halo of Andromeda is not visible even in the largest telescope. However, due to the fact that quasars with their glow "illuminate" it from behind, scientists were able to explore this area.

Using light from 43 distant quasars, galactic nuclei and some of the brightest space objects in the universe, astronomers were able to map the huge halo that surrounds the Andromeda galaxy.

If your eyes could make out the diffuse glow of this hot gas bubbling around Andromeda, you would see that this galaxy already occupies a third of our sky.

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How to see another galaxy?

Human intuition suggests that the distantastronomical objects should appear smaller in the sky than nearby objects. But intuition, as a rule, is not the best assistant when working with unfamiliar scales and structures of the distant Universe. In our solar system, only the Sun, Moon and random comets have a pronounced size that can be seen with the naked eye. The planets are just dots.

But if you go even further, everything will start to change. As the distance increases the scale of objects increases even faster, so they seem a lot more.

This pattern continues as you move awayfrom the earth. The closest large galaxy cluster is the Virgo cluster, which contains about 1,500 galaxies; it is so large that it fills the entire constellation after which it is named. The Virgo Cluster is part of the larger Virgo Supercluster, which includes our Milky Way. The Virgo Supercluster, in turn, is a subset of an even larger supercluster called Laniakea, one of the largest structures in the known universe.

Take for example a recent comet NEOWISEthat could be observed from Earth. The solid part of the comet is tiny, no more than 5 kilometers wide, how did we see it? The fact is that the gas and dust that "boiled away" from the comet and formed its common trace in the environment - have spread a million times further.

The dust and ion tails of Comet NEOWISE were easily visible from Earth, although the comet itself was so small that even the Hubble Space Telescope could not see it.

What will happen to the Earth after the collision of galaxies?

As it stands, the collision of the Milky Way andAndromeda poses no danger to us. But what will happen when the galaxies get close to each other? Both galaxies will be attracted to each other until the black holes at their centers eventually merge into one. Once this happens, our solar system will become part of a completely different galaxy - elliptical.

At the moment, the Andromeda galaxy is moving towards the Milky Way at a speed 400,000 kilometers per hour... At this speed, the globe can be circled in just 6 minutes.

Experts believe that despite suchlarge-scale event, the Earth will still survive. Together with the rest of the solar system. Scientists assume that our planet will hardly be affected by this intergalactic collapse, since both galaxies have a lot of free space. Nevertheless, it will be very interesting to observe the event from Earth.

If, of course, life is still preserved on it by that time. And then by this time the Sun can already swallow the Earth.