Not even 10 feet away. And it was a fast one, too. That was a very big comet. Even so, only a few seconds of the impactor’s speed made it into the atmosphere, and only the meteoroid’s heat from hitting the ground burned the air just a fraction of a percent of the meteoroid’s weight, which is roughly as much as the impactor’s width and length. That also only caused a tiny bit of heating, and not enough to melt its path out of the atmosphere. The heat was much lower than expected, even without looking at the meteor’s color.
In the end, the impactor burned up and cooled in the atmosphere, and is likely the cause of the meteor’s speed. So, what’s the impactor’s impact on the comet? Well, the comet has been growing the past few hundred years, and the meteor impactor’s impact is what’s allowed it to grow. It’s still tiny, and can’t keep up with the comet, but it’s able to burn more, and faster, and therefore it creates more light and heat.
It gets even bigger. Now we all know that, no matter what, if a comet is going to get any larger, it can probably only do so by hitting a planet. However, that’s not much of a problem. The Comet Encke. It was almost certainly a comet hit by a planet, and the impact has likely made the comet much bigger. Maybe ten times bigger. The comet was a good ten times heavier than a typical moon, too, so even though the impactor wasn’t that high, it still created a lot of energy, including heat. The impactor’s mass will accelerate the comet up toward the sun, and perhaps some more energy will make it reach the point where it could start moving away from the sun. I’ll give the comet another try. It’s probably going to get a bit bigger than the comet would be in ten thousand years or so. I’ll say “maybe,” because the comet is a lot more of a mess than it is now, and it’s too hard to try. It could go either way very soon. Maybe it’ll become a star or a comet, and it’ll be a really, really cool object. Or it might simply have been pretty lucky, and it will burn up. But I’ve never seen one that way, and I see lots of comet burnups that I don’t know how to explain. I just don’t think anyone has.
One theory, by a man who makes a living explaining the world, for making lots of predictions in the future, is this : a comet will hit Earth the way a moon hits the Earth, on September 17, 2012, and it will grow big enough to grow into a planet, and maybe just grow further, making it really big and bad and bad. This is the most likely interpretation of the comet’s impact. It has some details that bear on this: the comet is pretty low on the solar system’s gravity-budget, and it will hit Earth on September 17, so it gets a lot of time. And even though it hits someplace on this date, this is not actually the sort of place “it has to” hit. That place may be somewhere else, or it will probably be really, really close. But, that’s enough of the big-bang stuff for now, and the next post will be about that.