Credit: ACS Science & Engineering Team, NASA

Recently (well, in 2012), a groundbreaking find was brought to us by the Spitzer Space Telescope, with NASA scientists suggesting that the vast expanses of background infrared radiation in our skies have a very plausible explanation...

In several previous articles, we covered the existence of real-life shooting stars, or hypervelocity stars, which are stars that are essentially flung out of their home systems and even their galaxies. In addition to these, there are also believed to be thousands, if not millions of stars discarded during galaxy mergers. The result of these mergers are a stream of stars known as "tidal tails".

Many great examples of said mergers exist (understandable since events such as this are a regular occurrence), with the most prominent being the Antennae Galaxies and the Mice (pictured above).  Both objects actually consist of two once-separate galaxies that were drawn together by their mutual gravitational pull. Once they became too close, the galaxies began to intermix, eventually creating the incredible structures seen here.Antanna


As they vacate the system/galaxy, the gaseous and particulate detritus left in their wake are like a blood trail leaving back to the scene of a crime. Part of this is because the mergers result in an epic wave of star-formation, while part of it lies in the fact that a lot of debris is flung throughout the intergalactic medium. The prevalence of these signature emission is what NASA scientists believe to be responsible for most of the background infrared radiation that pollutes our skies at night!

This is pretty groundbreaking since astronomers first thought that the infrared glow is evidence left over following the life and death of the very first stars produced after the big bang. Yet this suggestion seemed counter-intuitive. If that were the case, we would expect the glow to be much less prominent than it actually is. relic

Image Credit: NASA / JPL-Caltech

The image above is an artistic NASA representation of what they believe to be the star trails left behind from typical galaxies mergers. How cool is that? Not only do we see into history as we look at the stars at night, but also, we are able to see the footprints of creation all around us!


How the collision might look from a planet in the Milky Way (Credit: NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger)

Furthermore, these galaxy mergers give us insight into our OWN history. Here in about 5 billion years, our galaxy will collide with its nearest neighbor; the Andromeda galaxy. The change would have little to no effect on us though, as our sun will have destroyed our solar system about a billion years before the merger begins. Hopefully, the human race (or what's left of it) will have found shelter elsewhere - among the billions of other planets circling another Sun-like star in our galaxy. At the least, any surviving species will have quite a sight to behold.

Adding to the uncertainty, astronomers still have little insight (excluding heightened star formation activity) into what actually happens inside that galaxies that are in the process of merging. It's likely that nothing significant happens at all, but it must be said that the black hole located in the center of our galaxy could turn into a mini-quasar. Otherwise, the odds of a single star or planet colliding remain highly unlikely (after all, space really is big).

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