Good questions…

Forums Meteors The Winchcombe meteorite Good questions…

Dominic Ford


These are good questions, but as Richard suggests, they will probably remain unanswered for some time – and perhaps forever!

The orbits obtained by meteor cameras are only very approximate, and in particular it’s quite difficult to measure the velocity of meteors accurately. This is unfortunate, since even a small error in a meteor’s velocity can make a big change to the inferred orbit.

The result is that we don’t really know where this object was a few years ago, let alone any further back in time. Its composition will probably give us some clues about where it was 5 billion years ago, when the solar system formed. Where it’s been hanging out for the past 5 billion years, we can only guess.

But there are clues. Its aphelion is rather close to Jupiter, so in all likelihood it was thrown onto an Earth-crossing orbit by an encounter with Jupiter’s gravitational field. Was this recent? Probably yes. Earth-crossing orbits are quite unstable, so that encounter almost certainly happened in recent decades / centuries.

Has it had previous close encounters with the Earth? Probably not very close. If it had done, its orbit would have been perturbed. Specifically, its aphelion would no longer be close to Jupiter. The encounter would either have thrown it out the solar system (most likely), or closer in to the inner solar system (unlikely). But it probably has crossed the Earth’s orbit before. It would be relatively unlikely to hit a bullseye on the first attempt.

Best wishes,