The Andromeda and Milky Way galaxies merge

The merger of the Milky Way and Andromeda has begun

The Andromeda Galaxy, the closest spiral galaxy to our Milky Way, is not noticeable in our night sky unless you look for it. Under dark skies, however, you can see it without optical aid, but only as a faint blurry patch of light. But one day, in the distant future, Andromeda will shine in our sky, growing bigger and bigger… as it gets closer to us. And even though the two galaxies are still 2.5 million light-years apart, the eventual merger of our two galaxies has, in fact, already begun.

EarthSky Lunar Calendars are always in stock! We are guaranteed to sell – get one while you can.

The great expanse of galactic halos

The Andromeda galaxy is currently moving towards our Milky Way at a speed of about 70 miles (113 km) per second. With that in mind, our merger will occur in five billion years. But, in August 2020, the Peer-reviewed Astrophysical Journal published new search revealing that the collision between our galaxies is already underway.

News from the Andromeda Galaxy came from AMIGA projectwho uses the The Hubble Space Telescope to observe the distant surroundings of the Andromeda galaxy. AMIGA stands for Absorption Map of Ionized Gas in Andromeda. Nasa called him:

… the most comprehensive study of a halo surrounding a galaxy.

The Andromeda Galaxy, our Milky Way and other galaxies are all shrouded in a large envelope – called a galactic halo – which is made up of gas, dust and stray stars. Galaxy halos are faint, so faint, in fact, that detecting them is no small feat. These astronomers measured the size of the Andromeda Galaxy’s halo by examining how well it absorbed light from background quasars. They were surprised to find that the halo of the Andromeda galaxy extends a lot, many far beyond its visible limits.

Indeed, it extends up to half the distance to our Milky Way (1.3 million light-years) and even further in other directions (up to 2 million years). -light).

Do the halos still touch each other?

So, does this mean that the halos of the Andromeda and Milky Way galaxies are touching?

It turns out that from our vantage point inside the Milky Way, we can’t easily measure the characteristics of our galaxy’s halo. However, since the two galaxies are so similar in size and appearance, scientists assume that the Milky Way’s halo would also be similar.

In other words, it’s the faint halos of the galaxies that actually seem to have started touching. So, in a way, the collision between our two galaxies has already begun.

Visualize Andromeda’s halo in our sky

So what will the Andromeda merger look like?

NASA released the images below in 2012. These are artistic conceptions of what someone on Earth might see as the Andromeda Galaxy hurtles towards us.

The depictions below are based on careful measurements of the motion of the Andromeda Galaxy by the Hubble Space Telescope, with computer modeling of the inevitable collision between the two galaxies. Furthermore, a series of studies published in 2012 showed that – rather than staring at each other, as merging galaxies sometimes do – our Milky Way Galaxy and the Andromeda Galaxy will merge into made to form a single large galaxy. ellipticalWhere shaped like a soccer ballgalaxy.

Roeland van der Marelastronomer at the Space Telescope Science Institute, says Discover the magazine in February 2022:

Whether it’s a head-on collision or more of a peek, it doesn’t really affect the end result.

And it’s a new giant elliptical galaxy.

Another video of the Andromeda fusion

However, the Milky Way and Andromeda galaxies will not be the only ones involved in this merger. As shown in the video below, the other large galaxy in our Local Group of galaxies, i.e. M33, aka the Triangle Galaxy, will also play a role.

In the video below, you will recognize the Triangle galaxy as the smallest object near the Andromeda and Milky Way galaxies. Although the Triangle galaxy is unlikely to join in the merger, it could nevertheless at some point strike our Milky Way as it is engaged in a grand cosmic dance with the two larger galaxies.

What happens to stars and planets when galaxies merge?

across the universe, galaxies collide with each other. Astronomers observe galactic collisions – or their aftermath – using powerful telescopes. In some ways, when a galactic merger takes place, the two galaxies are like ghosts; they simply cross each other. This is because the stars inside galaxies are separated by such great distances. So stars themselves don’t usually collide when galaxies merge.

That said, stars in the Andromeda Galaxy and our Milky Way will be affected by the merger. The Andromeda Galaxy contains approximately one trillion stars. Meanwhile, the Milky Way has about 300 billion stars. Stars from both galaxies will be launched into new orbits around the newly merged galactic center. For example, according to the scientists involved in the 2012 studies:

It is likely that the sun will be propelled into a new region of our galaxy…

And yet, they said,

…our Earth and our solar system are in no danger of being destroyed.

Will humanity see the Andromeda merger?

So what about life on Earth? Will Earth Life Survive the Meltdown? Well, the sun will eventually become a red giant in about 7.5 billion years, when it increases in size and consumes the Earth. But even before that, the luminosity, or intrinsic luminosity, of the sun will increase. This will happen, ultimately, in a timeline of about four billion years.

As solar radiation reaching the Earth increases, the Earth’s surface temperature will increase. We could be experiencing a runaway greenhouse effect, similar to the one currently occurring on neighboring planet Venus. So there is a good change that life on earth will no longer be there when the merger ends.

But by then, perhaps some terrestrial inhabitants will have become spatial. Perhaps we will have left Earth, and even our solar system. We can still get the sight of Andromeda crashing into the Milky Way, just from a slightly different vantage point.

Read more: Hubble shows Milky Way is destined for head-on collision

Conclusion: the merger of the Milky Way and Andromeda has already begun. The two spiral galaxies will form a giant elliptical galaxy in 5 billion years.

Source: AMIGA Project: The Circumgalactic Environment of Andromeda*

Via Discover the magazine