Q: Evidence has shown this has happened 6 times in Earth's history. Do you think it will happen again and if so, when? No, there is an accurate way to answer it lol, they have something called the Torino scale where astronomers calculate the possibility of an asteroid hitting Earth. The closest one ever was measured for April 13th, 2036, which was later downgraded to a 0 from a 4 on the scale, so with that out of the question I was wondering if people thought perhaps in a thousand years, million years, or perhaps never. Duckie68, wow definitely interesting and helpful. Now if an asteroid were to hit the Moon, do you know how that would effect life on Earth?
A: Yes. The key element though is the phrase, 'in time'. The fact is, space is really big, and all the matter in the solar system, even in the universe, only takes up a really small fraction of that space. We've got plenty of big asteroids out there, and even more cometary bodies. We even have a general time frame. Every big (somewhat) confirmed asteroid collision has happened over a 65 million year cycle. Now a few things on our side. We've got Jupiter out there sweeping up the outer Solar system. That big ball has been using its gravity to sweep out excess asteroids and comets for a long time. So, there aren't as many big rocks as there were 65 million years ago. We also have a pretty good idea about a lot of the 'planet killer' asteroids out there. We have even spotted some of the plutoids out in the Kuipper belt, the zone where deep space comets come from. Hopefully we can have some clue before something gets dangerously close. Oh, and don't forget the whole 'space is big' part. With space being so big, and this planet being such a tiny target... However, we also have time working against us. The chance of a killer asteroid coming out of nowhere and hitting us would be like rolling a thousand dice, and every last one comes up with a '1'. Sure, it's not very likely, but if you keep doing that, day after day, year after year, century after century, it could eventually happen. In the past twenty years I recall lots of people claiming that near Earth asteroids were going to end all life. Well, the closest has never come closer then the moon. Right now, we're safe. The chances of anyone alive today experiencing such an asteroid collision are pretty darned slim. Hopefully by the time that we roll a thousand 1's, we will have some methods in place to keep the planet safe. Hope this helps, Cheers! ***EDIT*** Hitting the moon huh? Well, I was just going to say that there wouldn't be much of any terrestrial effect unless the asteroid was REAAAAALLY big, but... I'm going to have to run some numbers on this, but I wonder how much of an impact would be needed to give some moon rock escape velocity. Again, I'm pretty sure that we wouldn't have any big moon rocks rushing towards us, but if several thousand tons of moon dust somehow hit the upper atmosphere. That's a really good question! Let me work on it a bit! Cheers!