Yet, we're surrounded by distant danger. Every once in awhile, scientists will mention in passing that an asteroid the size of a football field has come within 2 or 3 million miles of the earth. Asteroids buzz by the earth every day, and estimates place the near earth objects at about 10,000. Most are no danger, even if they do hit the earth. The earth is sort of a cosmic vacuum picking stuff up all the time, every day. Scientists believe that much of our water came from space. That is lucky for us.
Then there is the sun. Every once in awhile, the sun has a bit of indigestion and burps a large ball of fire, known as a coronal mass ejection, into space. For most of earths history, earth has not been in the path of a smoke ring from the sun. There have been times when scientists were worried about it and have expressed concern. But that has usually been for our satellites. So far, we've been lucky to see the sun as a benign benefactor of life here, on earth.
We've all heard of supernovas. Supernovas are the end of the line for a star. When a star runs out of hydrogen to burn, then it burns helium, and then it start fusing helium to make oxygen. When the star fuses bigger atoms together, it grows into a red giant, like a giant balloon. When it runs out of fuel, the star collapses on itself and when the matter slams together at the center and goes boom, that's a supernova. Some us have seen the Crab Nebula. That's a remnant of a supernova. Heavy atoms like silver, gold, thorium, and uranium are made in supernovas.
While that's big, there's a bigger boom out there. It's called a gamma ray burst. Gamma rays are at the top end of the electromagnetic spectrum. Gamma ray photons are the most energetic forms of light and are beyond the range of our eyes to see. We usually detect them with special instruments as coming from stars, supernovas and gamma ray bursts.
I read about gamma ray bursts a few years ago. The last one I read about came from an object known as a magnetar. It's essentially a neutron star, but with a very strong magnetic field. The gamma ray burst came from a magnetar having what can best be described as an earthquake. That was a little blip for the magnetar, but to us, we measured an output of about 250,000 years of our suns output, in less than a second.
It is theorized that if one of those were pointed at the earth, and we were say, within 1000 light years of it, life on this planet would be mostly toast. Fortunately, those events are rare, maybe one or two every million years in our galaxy, and most recorded gamma ray bursts come from outside of our galaxy, placing them millions of light years away from us. I guess we can take comfort in that.
We are a putative force in the universe, and we have been blithely unaware of the forces at work in the universe for a long, long time. Maybe that's a good thing. It would be hard to get out of bed fraught with worry that we might be snuffed out by an asteroid, supernova or gamma ray burst.
Knowing about all this myself, when I'm down and I feel like nothing is going right, I remind myself how lucky I am to be here. For if the world were truly against me, I'd be about a millimeter thick.