The closest known planet outside our solar system is 10.5 light years away. There's only a handful of starts under 10 LY from Earth.
The other known planets outside our solar system are mostly
less than 300 light years away, not greater than. That's just because finding planets is harder the farther away the star is, so they've been concentrating on nearby stars in the search.
The first *direct* image of a planet around another star using visible light was taken in 2008, and only confirmed in this past June.
SPACE.com -- First Direct Photo of Alien Planet Finally Confirmed
The Earth takes about 200 to 250 million years to make an orbit around the center of the Milky Way Galaxy. Civilization is only about 10,000 years old. In terms of moving around the galaxy, the Earth has gone next to nowhere since civilization began.
I think you may not quite grasp the scale here.
The chance that the Earth will get hit by an object from outside the solar system is, for all practical purposes, zero. Space is big. Really big. Really vastly empty big. There's only a handful of stars within ten light years of Earth now, and that's only going to change on the order of millions of years, not thousands. For our purposes, there is nothing out there to hit us, and we are such a tiny target that hitting us is nigh impossible.
Now, getting hit by a rock that's already within our own solar system? That we can show has happened rather frequently in the past, so that it is likely to happen again.
I don't think I'm misunderstanding the scale. It's all a matter of statistics. I don't think I said that the Earth has passed all the way around the Milky Way in 10,000 years. What I was saying was that the article I'd been reading had suggested that we've experienced a period of thousands (or a few million, can't remember the number) of years of time, wherein Earth was going through an area of the Milky Way where there was less debris. As a result, we may have had lower numbers of large impacts.....a stability that partly enabled the development of human civilization. The article said that the space ahead may be rougher, increasing the chance of large impacts.
There are space rocks out there of all sorts of different sizes. We know we've been hit by different rocks over hundreds of millions of years. There are craters of various ages all over the earth. Heck a guy was in the paper earlier this summer for getting his by a speck of cosmic dust (relatively speaking) that burned a hole through his hand. I saw a picture of a car that got hit by a small one, which basically destroyed an end of the car.
This stuff hits us. Most of it gets burned up in the upper atmosphere, but every so many thousand or million years, something bad happens, and we get hit by something bigger. It's not like the rock that created the Chixculub crater and contributed to the major extinctions 65 mya was the first large rock that's hit us. There's some evidence apparently that an extrasolar event, possibly another meteor strike contributed to a mass of extinctions among megafauna 10,000 + years ago.
Statistically, we've been hit before, and we'll be hit again. The longer we go without a big strike, the greater become the odds that we *do* get hit again. That doesn't mean tomorrow, or in 10 years, 100 years, 1000, or 10,000. But it's likely going to happen. When is the question. If it's 1,000,000 years from now....well, humanity might not be around anymore....or our descendents might not be recognizable to us at that point, so for all intents and purposes it wouldn't matter.
It's just like earthquakes. Everybody buys earthquake insurance right after an earthquake occurs. But that's when, statistically, you're less likely to have another major quake. But if you're in a quake zone, then every year that goes by without a quake increases the chances one *will* occur....making having insurance against it more and more important.....yet people become less and less likely to buy that insurance, the longer it goes without a quake.
I absolutely know that space is vast. Immensely vast. There's lots of emptiness out there. But there are also rocks and other things, each with their orbit, as our planet has an orbit, our sun has an orbit, and even our solar system has an orbit. Everything's out there moving around. But we know that there there are big rocks in and around our solar system perfectly capable of radically transforming life on this planet, by wiping out pretty much every mammal bigger than a mouse. So....Spaceguard has been working to collate information about all the rocks 1 mile across or bigger, and is supposed to have identified 90% of them by now.
But governments haven't been able to put together enough funding of $300-400 million, to allow them to identify 90% of asteroids 140 - 1000 m in size. These are the rocks fully capable of obliterating a country the size of India, with like 16% of the world's population. That would be an example of a very bad day that doesn't destroy civilization as we know it.
Now aside from knowing that the rocks are there, I'm not sure if we even have the capability to do anything about them. I don't think we'll be landing Ben Affleck and Bruce Willis on an asteroid anytime soon. And if we *do* develop the ability to interfere with one of these space rocks, and prevent a collision, we still have to *find* them......and we're not really looking (for rocks between 140 and 1000 meters) from what I understand. At least not in an organized fashion. I do think it would be nice to know. Our calculations are good enough that scientists can look at an asteroid, observe its orbit, and say "well, it'll come close in 2079, but not close enough........but 2208 might be a bad year for somebody or many somebody's".
The *chances* of any of this happening are very low in our lifetimes. But they're not 0. Spread that out over a longer period of time.....100, 500, 1000 years, and they start to climb. If the Tunguska explosion of 1908 was in fact an asteroid detonating in the atmosphere, it's evidence of the scale of the problem. There's lots of uninhabited land (and water) on earth. But imagine if that event had happened over a city, instead of over Siberia.
Volcanoes are another way that life can be negatively impacted. They're the main suspect behind the Jurassic extinction event, are they not? Where 50% of life on the planet was wiped out? It doesn't even take something that major. The volcano eruption in Iceland this summer caused how much interference to air travel? How much money was lost? And that was a relatively small one, from what I understand (geologically speaking).
In any case, the only reason I brought this up is to basically to illustrate the point that space is big (heck, earth is big), and man is small. We can control what we can control.....and you just cross your fingers the rest of the way. And I'm not saying this to indicate that I think an asteroid's going to hit tomorrow. Or the day after. Or the year after. The greater the perceived negative effect of something happening, the greater the chance we estimate that it will actually happen. I understand that. A big rock wiping out all life on the planet? Possible, but unlikely. A big rock wiping out a country? More possible, but still unlikely. A big rock wiping out a city? Probably even more possible, but still very, very unlikely. An individual is still in far greater danger smoking, driving their car, or drinking pop. Someone's probably more likely to get hit by a bus, while worrying about getting hit by an asteroid
.
But if we're dreaming big dreams, and wanting to ensure that humanity survives, then exploration of space becomes a necessity, rather than sitting here on this one planet. And that kind of project, such as terraforming Mars, could take hundreds of years. A project like that is probably more likely to happen than flying to another solar system and populating a planet 10 light years away. But I think that the resources and political will to do any of this aren't really there. I mean, in many democracies, people can't even come to an agreement about whether or not to build a bridge in one place or another. And we're talking about coming to agreements about colonizing other worlds?
I had read that, despite the expense of the NASA space program, the Apollo missions, and all of that, these explorations have still resulted in scientific and technological advances that resulted in financial benefits that significantly outweighed the expenses of those programs. But the voting and tax paying public of many nations doesn't really *get* it. So I'm not sure that the political will will be there to support the work needed to accomplish these kinds of long term goals.
So, this is why I think we *should* be doing it, but that I don't think it's going to happen.
Banshee
