Forgive me if my use of words is inadequite or incorrect. (re:asteroids/meteorites)
Do objects hurtling through space strike the daylight side of the Earth?
The sun is a big target, and has a lot of gravity. Is it possible for objects to go past it to strike the Earth, or do they all come from the night sky? Traveling through space, not having to bypass the sun seems liklier. I really don’t know. Yesterday I told a guy it couldn’t happen (meteorite striking the daylight side of the Earth) but now I’m not so sure.
Yes, meteors strike the earth on both the sunlit and dark sides. The sun is roughly 93 million million miles away, so meteors have plenty of room to get past it. Meteors have to be pretty bright to be seen against the daytime sky, but plenty hit then anayway.
Here’s a report on a daytime meteor fromTexas: http://www.meteorobs.org/maillist/msg07419.html
We recently had a fairly close call from a large chunk of something that went undetected until it was already past us, due to the fact that it came from the direction of the sun. Apparently these types of objects are almost impossible to detect, so if one does happen to end up on a collision path with the earth we won’t know until it’s too late.
I’ve also seen videos of meteors streaking through the daytime sky, but not sure what direction those came from.
When I went to the meteor crater outside Windslow AZ they had an artists depiction of the meteor striking the Earth during daylight. I thought it was an error. Now I know better.
Also, keep in mind that an object can come in from the night side of Earth and get caught in the gravitational pull, orbit the planet for a while, and then finally plummet to its death on the day side.
It’s not all that easy, actually. In general, if an object is in orbit around the Earth, it’ll stay in orbit, and if it’s not, then it won’t get into an orbit. You need to have some other forces present to capture an object or cause an orbit to decay. The atmosphere can cause an orbit to decay, if the perihelion is close enough to the the planet, but it wouldn’t be able to do much to capture an object in a single pass, and the Earth plus atmosphere is only slightly larger target than the Earth’s surface. The Moon, or some other body, could allow for a capture, but it’s pretty tricky to get it to work just right: Usually, you have to be trying for something like that and aim pretty well.
The same is true for the Sun, by the way, or for any other gravitating object (including black holes, if you’re a reasonable distance away): Most of the things which hit the Earth are already in orbit around the Sun, and if they don’t hit it the first time around, they’re not likely to for a long time.
You will probably, however, get more meteors during the AM hours than the PM hours, due to the motion of the Earth around the Sun. I don’t have any statistics for how big this discrepancy is, though.
Well, I wasn’t referring strictly to “orbit” per se, but as a (relatively) slow-moving piece of space debris gets closer to the planet, it’ll be attracted by Earth’s gravitational pull. I’m just speculating the possibility that some things can spiral in, instead of just hitting straight at the planet, like what we saw in Deep Impact (what a horrible movie that was).
Yep, people have this idea of a “decaying orbit”, where something spirals in slowly. But that never really happens unless the object is inside the atmosphere of the body it is orbiting. An object headed for earth will have either a hyperbolic orbit (which means it heads back into space) or an elliptical orbit (circular being a special case of elliptical). Hmmm, and if something is going to hit the body it would have a parabolic orbit.
No spirals.
It would also be very rare for an object to establish an elliptical orbit. It would have to be almost perfectly positioned with the perfect velocity. And most objects that do get into an elliptical orbit are going to be wildly eccentric.
So generally either an object hits us or it misses us and continues on, perhaps in a slightly different solar orbit if it came close.
I’ve seen a few during the night, they’re so much easier to spot and I just star gaze occasionally. I’ve seen some pretty cool ones, though probably nothing compared to the amateur astronomers amongst us.
I always thought I saw one during daylight hours though, it was a light smoky streak in the sky that briefly flared up into a few sparks and then nothing. There was noone else around at the time to look up and say “hey, cool,” so I’m only assuming.
quick addendum- I’m sure it wasn’t a firework as it was definatly not travelling upwards and it wasn’t really the time of year for that sort of thing anyway but i’m open to interpretations.
Again, unless you have some other body involved, it never happens. By the way, parabolic orbits don’t have any particular relation to collisions, either: An object can swing past on a parabolic orbit, or it can hit on a hyperbolic or elliptical orbit (although for something to hit the Earth on an elliptical orbit, it would have to have been launched from Earth, too).
Pushkin, you may well have seen a meteor. It’s probably a bit late now (you didn’t say when this was, but I gather it was several years ago), but you can usually do some checking afterwards to see if anyone else saw it. For one bright enough to be seen in the day, there were probably other witnesses, and some of them probably got the word out.
I’ve seen a video of a meteor travelling over a lake in Montana? Wyoming? from south to north in the 80s, at a rate that would have taken it from horizon to horizon in about a minute.
It entered at too shallow an angle, so it skipped back into space, but eh pictures and video were pretty spectacular. Middle of a sunny summer day, swimmers and boats on the lake, and this what looks like a rocket zooming across the sky overhead.