As scientists have demonstrated, our solar system seems to be a pretty special place. Namely because of us, but we aren’t the only reason. Our local neighborhood happens to lie within a region in our galaxy that is lacking in many of the things that make certain planets uninhabitable; things high energy radiation from supernovae, rogue stellar-mass black holes and densely packed regions containing hundreds, perhaps even thousands, of stars. The list goes on and on. Simply put, our solar system meets all of the requirements for Earth and everything on it to thrive.
However, that’s not to say that Earth doesn’t have its fair share of obstacles. For starters, scientists know that Earth is encased in huge “belts’ of radiation that seems impossible to safely traverse. We also know that Earth is technically located within the Sun’s atmosphere and that it might even be surrounded by a halo of dark matter so large, it would make our planet look like Jupiter from afar.. that is, if we could actually see it.
Astronomers have now confirmed yet another surprising find to the list of things Earth is surrounded by.
Long ago, physicists believed the vacuum of space to be completely empty, devoid of all types of matter. However, later research revealed that it is, in fact, pervaded with all sorts of weird things, like particles that pop in and out of existence. However, when astronomers went looking for these things in our neighborhood, they noted that, contrary to other parts of space, IT is virtually empty inside, harboring only a single atom for every liter of gas in spacetime, which raised the question: where the heck is everything?
Scientists went on to suggest that the reason most of the expected material is missing is because we are positioned inside of an immensely large bubble, composed of nothing but the byproducts of one of nature’s most energetic events; supernova explosions.
Why would they come to such a conclusion, you might ask? Well, the assertion is partially based around the discovery that, from above, Earth is being bombarded by a barrage of x-ray radiation coming at us from all sides. This radiation has since been linked to supernovae that blasted off somewhere remotely close to us in the somewhat-recent past, or about ten million years ago.
Naturally, not all astronomers agreed that the x-ray emissions were coming from dead stars, thus the local bubble was just a pretty hypothesis. In fact, more than a few scientists suggested that the bubble doesn’t exist at all and that the soft X-ray diffuse background is actually the result of charge exchanges. This refers to the way in which electrically charged solar wind affects neutral gas. Through these interactions, the solar wind often robs neutral gas of its electrons. The subsequent x-ray glow looks remarkably similar to the glow left behind after a star vomits its innards up in the throes of death.
Since no consensus was reached on the issue, a team of researchers — including F. Scott Porter (from the Goddard Space Flight Center) and Massimiliano Galeazzi (a physics professor from the University of Miami in Coral Gables) — created and launched a device, called DXL (short for ‘Diffuse X-ray Emission From the Local Galaxy‘),that specializes in measuring charge exchange radiation. Merely minutes after it was launched in 2012 (one of NASA’s rockets assisted in getting it about 160 miles above Earth’s surface), its objective was met, with the team learning that just 40% of this all-encompassing radiation originated from within our solar system, once again putting the bubble hypothesis back into play.
This bubble would be 300 light-years across and shaped like a peanut (it’s extremely hot as well, with temperatures hanging around a million degrees). Under this scenario, nearby supernovae would essentially expel most of the missing ingredients generally found within “empty” space, leaving leftover radiating gas in its place (its hot diffuse gas would be the primary source of the x-ray emissions).
“This is a significant discovery,” said Galeazzi. “It affects our understanding of the area of the galaxy close to the sun, and can, therefore, be used as a foundation for future models of the galaxy structure.”
The team still isn’t sure just which star is responsible for the bubble, but one of the most promising candidates is a stellar core. dubbed Geminga (a pulsar in the Gemini constellation). However, it’s likely that multiple stars contributed to its existence, when, as a team member put it, several stars popped off like popcorn, all happening around the same time (unusual since only a handful of supernovae ignite in every galaxy each century). Geminga itself lies about 800 light-years from Earth — a number that seems both close to us and far away at the same time — yet its effects were felt here on Earth.
In fact, if a supernovae were to ignite within several hundred light-years of our planet, it would almost certainly wreak untold havoc on Earth. The gamma-ray beams, if their poles are pointed directly in Earth’s line of fire, would essentially destroy our ozone layer, which would, in turn, leave us vulnerable to high-energy radiation (among other things). There’s even a good chance it could wipe out all life on Earth.
All in all, supernovae are bad news for inhabited planets, but what would you expect from an event so energetic, it unleashes more energy in mere moments than the Sun will release over the course of its entire lifetime?