Andromeda Galaxy Our Closest Galactic Neighbor Revealed

The Andromeda Galaxy is a massive swirl of roughly a trillion stars located just south of the Milky Way. Yet, it will crash with our own galaxy billions of years from now.
On a clear night away from city lights, you can just make out a long, fuzzy blob known as the Andromeda Galaxy if you look toward the constellation Andromeda.
The Andromeda Galaxy, or M31, is our Milky Way’s nearest major companion, located around 2.5 million light-years away. As a result, it is frequently apparent to the naked eye as the furthest object.

Two European Space Agency observatories collaborated to cast a new light on the Andromeda Galaxy. In this, the most comprehensive image of the Andromeda Galaxy yet captured at infrared wavelengths, Herschel observes rings of star formation, while XMM-Newton finds dead stars emitting X-rays into space. As the galaxy merges with the Milky Way, its spiral structure, which is identical to that of the Milky Way, will transform into one huge elliptical galaxy.

The finding of the Andromeda Galaxy

For thousands of years, ancient astronomers may have just speculated about the nature of this misty region. In 964 A.D., while compiling a treatise on “Fixed Stars,” a Persian astronomer named Abd al-Rahman al-Sufi discovered the Andromeda Galaxy. He dubbed it Andromeda and saw the Great Magellanic Cloud, the Milky Way’s much smaller satellite galaxy. The Andromeda Galaxy was described as a “small cloud” in the sky.

Nevertheless, astronomers did not detect Andromeda’s singularity until the 1800s. This is because, until about a century ago, astronomers believed the Milky Way was the universe’s center of gravity.

For a long time, the term “nebula” was used to denote any fuzzy night-sky object that wasn’t a comet, and it was employed by viewers using telescopes to look for comets. Spiral nebulae were nebulae with spiral formations, such as Andromeda. Nevertheless, in 1864, an English astronomer named Sir William Huggins used a prism to isolate and analyse the different colours of light from many nebulae. Huggins discovered that the light spectra of M31 varied greatly from those of numerous other nebulae.

The Great Galaxy Controversy

Several astronomers began to witness supernovae erupting in Andromeda during the next several decades. Heber Curtis, in particular, computed the distance to Andromeda based on the brightness of the explosions. He calculated the distance between these “spiral nebulae” to be 500,000 light-years, well outside the Milky Way’s borders.

Vesto Slipher of Lowell Observatory in Flagstaff saw M31 using the 24-inch Clark Telescope a few years ago, noting its astounding rate of ascent. Except for three spiral nebulae, all of the others Slipher measured (more than a dozen in all) were moving away from Earth.

Vesto Slipher of Lowell Observatory in Flagstaff saw M31 using the 24-inch Clark Telescope a few years ago, noting its astounding rate of ascent. Except for three spiral nebulae, all of the others Slipher measured (more than a dozen in all) were moving away from Earth. These findings formed the basis of the famed “Great Argument” between Curtis and the ambitious young scientist Harlow Shapley. A vast number of astronomers supported Shapley’s long-held belief that the Milky Way was the entirety of the Universe. Yet, evidence suggested the presence of “island universes” in Andromeda and other perplexing spiral nebulae. Years would pass before the argument was finally settled.

The Milky Way and Andromeda meet in Milkomeda.

We now know that the Andromeda Galaxy is a different island world from our own. This will not always be the case.

As Slipher’s observations first indicated, the Milky Way and Andromeda will approach a little too close during the next five billion years. The two will trade light hits, ripping stars apart and twisting them into long tails.

During these trips, the Andromeda Galaxy will be visible in our night sky as seen from Earth. Yet, once the two are completely intertwined, they will join to form one massive group of stars. But, rather than a spiral galaxy, the end object will be an elliptical galaxy. Milkomeda is the name given to this future galaxy by astronomers, and mergers like this one are common.

Galaxy mergers frequently result in powerful bursts of star formation, despite the fact that they appear to end in destruction. Although it is unlikely that humanity would survive long enough to see it, it will be visible from our solar system.

Yet, the aftereffects of the Milkomeda collision will flood our night sky with bright new stars. As a result, rather than destroying both galaxies, the merging of the two may result in the production of new galaxies.

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