Andromeda galaxy real size? Yes. This image really depicts what the night sky would look like if the Andromeda Galaxy – the galaxy next door – were brighter. Original background photo of the month by Stephen Rahn. Andromeda Galaxy image via NASA. Composite photo by Tom Buckley-Houston. Not convinced? Here is a similar image of APOD.
The image above makes the rounds on social media this week. It’s true. The neighboring Andromeda galaxy occupies about 6 months in diameter across the dome of our sky. But the galaxy is obviously not that bright. You need a dark sky to see it, and even then it’s a barely visible fuzzy patch of light. To appear as bright as in the image above, the Andromeda Galaxy would have to be closer. If it was close enough to see so clearly, it would even appear larger on the dome of our air. And that will happen someday! The Andromeda Galaxy is currently traveling toward our Milky Way at a speed of about 70 miles (110 km) per second. Eventually, the two galaxies will merge. Between now and that possible fusion, every creature that lives on Earth will grow into the Andromeda Galaxy and larger en BIGGER in our night sky.
The Andromeda Galaxy is now about 2.5 million light-years away from us. The artist’s concepts below, released by NASA in 2012, show what will happen to the night sky of the earth as the Andromeda galaxy smells like us.
Bigger view. | This series of illustrations shows the predictive fusion between our Milky Way galaxy and the neighboring Andromeda galaxy.
First row, left: Present day.
First row, right: In 2 billion years, the disk of the upcoming Andromeda galaxy is noticeably larger.
Second row, left: In 3.75 billion years, Andromeda fills the field of view.
Second row, right: In 3.85 billion years, the sky has been burned with new star formation.
Third row, left: In 3.9 billion years, star formation continues.
Third Row, Right: In 4 billion years, Andromeda is stretched in time and the Milky Way is twisted.
Fourth row, left: In 5.1 billion years, the cores of the Milky Way and Andromeda appear as a pair of bright lobes.
Fourth row, right: In 7 billion years, the aggregated galaxies form an enormous elliptical galaxy, whose light core dominates the night of the sky.
Image via NASA / ESA / Z. Levay and R. van der Marel, STScI / T. Hallas / A. Mellinger.
The descriptions above are based on sharp Hubble Space Telescope measurements of the motion of the Andromeda Galaxy, followed by computer models of the irreversible future collision between the two galaxies. A series of studies published in 2012 showed that – instead of looking at each other, as fusing galaxies sometimes do – our Milky Way galaxy and the Andromeda galaxy will in fact merge to form one large elliptical, or football-shaped, galaxy.
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 – M33, also known as the Triangulum Galaxy, will also play a role. In this video you will recognize the Triangulum galaxy as the smaller object near the Andromeda and Milky Way. Although the Triangulum galaxy is unlikely to participate in the merger, it may hit our Milky Way at some point if it is engaged in a large cosmic dance with the two larger galaxies.
Across the entire universe, galaxies collide. Astronomers see galactic collisions – or their imitation – through their telescopes. In some ways, when a galactic fusion takes place, the two galaxies are like ghosts; they just go through each other. This is because stars in galaxies are separated by such large distances. Thus, the stars themselves typically do not collide when galaxies merge.
That said, the stars in both the Andromeda Galaxy and our Milky Way will be affected by the merger. The Andromeda Galaxy contains about a trillion stars. The Milky Way has about 300 billion stars. Stars from both galaxies will be thrown into new orbits around the newly merged galactic center. For example, according to scientists involved in the 2012 studies:
It’s likely that the sun is moving into a new region of our galaxy …
And yet, they said,
.. our Earth and solar system are not in danger of destruction.
How is life on earth? Will earthly life survive the fusion? Astronomers say that the brightness, like intrinsic brightness, of our sun will gradually increase over the next 4 billion years. As the brightness of the sun increases, so does the amount of solar radiation that reaches the Earth. It is possible that – by 4 billion years from now – the increase in the Earth’s surface temperature will cause a circular breeding effect, perhaps similar to what is happening now on the planet next door, Venus, whose surface is hot enough to melt lead. No one expects to find life on Venus. It looks like life on earth will not exist 4 billion years from now.
What’s more, our sun is evolving as well. It is expected that they will eventually become a red giant star. The outer layers of the sun will swell in the space of the solar system, so that Earth itself will be swollen by the outer layers of the sun. That is expected to happen in about 7.5 billion years.
Perhaps by that time some earthly inhabitants would have become space-dwelling. Maybe we will leave Earth, and even our solar system. Do you think so? Let us know in the comments below.
Read more: Hubble shows Milky Way destined for head-on collision, via NASA in 2012
Bigger view. | Artist’s concept of a stage in the predictive fusion between our Milky Way galaxy and the adjacent Andromeda galaxy, as it will work out in the billions of years to come. In this image, represented by the night sky of the earth in 3.75 billion years, Andromeda (left) fills the field of view and begins to drown the Milky Way with tidy pull. Image via NASA / ESA / Z. Levay and R. van der Marel, STScI / T. Hallas / A. Mellinger.
Bottom line: Billions of years from now expect our Milky Way galaxy and the Andromeda galaxy to merge. This post contains photos and video illustrating the difficult fusion and shows how the Andromeda galaxy will appear in the night sky of the earth over the next 7 billion years.
The M31 Velocity Vector. I. Hubble Space Telescope accurate measurements for motion
The M31 Velocity Vector. II. Radial trajectory to the Milky Way and implied local group mass
The M31 Velocity Vector. III. Future Milky Way-M31-M33 Orbital Evolution, Fusion, and Fate of the Sun.
Via NASA
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