David J. Eicher, editor in chief of Astronomy Magazine, gave an interesting talk at this year's Northeast Astronomy Forum entitled "Does the Universe Really Care About Itself?" I want to share one theme of Dave's lecture that I believe everyone needs to know and consider. Sit down, I'm about to be Mr. Doom and Gloom.
You may have heard that our Sun has about 5 billion years of life left in it. No worries, you think, that's a long way off...right? But, did you know that long before the Sun meets its eventual demise, it will swell to the point where it'll boil off the Earth's oceans? That will happen in a mere 800 million to 1 billion years from now. Still far into the future, huh? Well, it gets worse. We don't even have that much time left to live on this world (told you I was going to be gloomy).
Every 100 million years or so, a 10-kilometer size object strikes the Earth causing a global extinction. Meaning from a statistical probability standpoint, the planet will see eight to ten such events BEFORE the oceans go bye-bye. The last one happened about 66 million years ago and killed all the dinosaurs...remember that one? Luckily some little rodent-like mammals, and all the cockroaches, managed to survive and along we came. But...it gets worse.
Every 500,000 years or so, a 2-kilometer wide rock hits us. When this happens next, it will make a crater nearly 30 miles wide and will cause everything within 150 miles to instantly burst into flames. Everything within about 400 miles will also probably catch fire from all of the ejected debris re-entering the atmosphere. The ozone layer of the atmosphere (you know, the layer that keeps all that cancer-causing UV radiation from reaching our bodies) will disappear for years. There will be global crop failures and some extinctions. Oh, and summer vacations will be canceled that year.
But...it gets even worse. About every 200,000 years, a 1-kilometer wide rock will take a shot at this blue marble. While the effects from an object of this size are less than the larger impacts, you still don't want to be within 200 miles of it unless you have a really super-duper big bag of marshmallows to roast.
I am writing this because I don't think most people realize the extent of the cosmic shooting gallery we live in. THIS is the main reason why astronomy and space exploration are so critical to humankind. Sure, it won't cure hunger or produce a vaccination against HIV but that's not what astronomy and space exploration are trying to do. Harsh truth coming up -- if we intend to continue on as a species we are going to have to leave this rock someday. I realize the sense of urgency may not rank right up there with global warming, but it should. We can see global warming happening, we may not see the threat from above until it is too late. And, at this point in our evolution, there is absolutely nothing we can do about it. But, we CAN change that if we want to.
Now that you know the reality of our situation, get ready to participate in AsteroidDay on June 30th, 2015. http://www.asteroidday.org/