There’s something out there.
Something that happens every day. If it were to happen at the right distance, and point in just the right direction, it would obliterate everything on Earth’s surface. We wouldn’t have much warning, and any preparation would be meaningless. There would be nothing we could do to stop our impending annihilation.
I’m talking, of course, about gamma-ray bursts.
Hide Under Your Desk And You’ll Be Fine
Gamma-ray bursts are the most powerful known phenomena in the universe.
Don’t believe me? Gamma rays alone are the strongest (highest frequency) and most dangerous form of electromagnetic radiation. Bursts of these rays emit ‘more energy in a few seconds than our sun will during its entire energy-producing lifetime,’ and a few seconds would be all it takes to decimate the Earth’s ozone layer and lead to an incredible mass extinction event.
Gamma-ray bursts are the result of the rapid collapse of high-mass stars, or a collision between binary neutron stars. In either case, gamma radiation shoots out in two distinct beams from the star, one at each pole, sending powerful, narrow streams of electromagnetic radiation shooting through space.
They can last from milliseconds to several minutes, traveling thousands of lightyears, and anything in their path — in this case, Earth — would experience a number of terrible effects.
The funny thing about gamma-ray bursts, however, is that at least one is observed every day. Some are even visible to the naked eye. Thankfully, all of those observed to date have occurred billions of light years away, well beyond the confines of our own galaxy, and the Milky Way itself doesn’t seem likely to produce any Earth-destroying bursts any time soon.
And, obviously, no gamma-ray bursts have hit Earth since humans arrived on the scene. Yet.
No, They Won’t Give You Super Powers
If, however, a gamma-ray burst occurred within the Milky Way Galaxy, and was aimed directly at Earth, it would be Lights Out for most, if not all, life on the planet.
It’s possible that some deep-sea organisms would survive, shielded from the brunt of the radiation by the ocean waters. Even then, the depletion of the ozone layer would spell rough times ahead for anything left alive.
First, we would likely see, with our naked eyes, an explosion out in space that would appear as bright as the sun. That would be the supernova. Once the invisible, deadly beam from one of its poles shot toward us, even if we knew it was coming, it would simply be a matter of time.
The scorching, fiery doom wouldn’t only affect the side of Earth facing the gamma rays. While Earth’s atmosphere would initially protect the planet, it would be cooked fairly quickly, superheating the planet’s entire surface. Beyond the initial effects, the gamma rays would potentially also bring about acid rain, lead to photochemical smog, which would darken the skies, which would unleash a terrific cosmic winter and, last but not least, expose Earth to harmful cosmic radiation.
So, what we’re talking about here is a really, really, really bad day for all life on Earth.
Has Earth Already Been Hit By A Gamma-Ray Burst?
When we talk about “world-ending” scenarios, what we really mean is “life-ending” or, even more specifically, “human-ending.”
That’s because it’s very, very difficult to destroy Earth itself. Only the sun will have that honor, and only if, in death, it expands beyond Earth’s orbit. Otherwise, Planet Earth has already witnessed a plethora of doomsday scenarios, from supervolcanoes and (maybe) rogue planets to ice ages and asteroid impacts.
And, you know what? It may have also already experienced a gamma-ray burst, leading to an ancient mass extinction event (yeah, we’ve missed all the cool stuff, right?).
By ancient, I mean about 450 million years ago, during the Ordovician-Silurian extinction event. It’s theorized that the mass extinction of this time was caused by a gamma-ray burst, given an observed “pattern of higher UV radiation” found to correlate with that time period. The mainstream thought is that the event was instead caused by climate change, but gamma rays are still on the table.
Our biggest threat today in regards to gamma rays are the World Rayet stars, which have been described as “ticking bombs” because they’re massive, hot, and rapidly losing mass. WR 104, in particular, sits a cool 8,000 light-years away, and is considered a “potential threat.” It’s a massive, binary star, and may be aligned in such a way that if it were to go supernova and produce a gamma-ray burst, we could be in serious trouble.
So, you know, look out for that.
For now, we have satellites like NASA’s SWIFT hanging out in space, hunting for gamma-ray bursts and gathering information on these powerful cosmic death rays. There’s not much we can do about them. We can only sit here, powerless, and hope all we ever do is observe…