Astronomers catch video of near-miss asteroid

[Alastair Rae]

Story and video on nature.com.

[Cath]

Three Earth Radii - that's a bit close isn't it!

Pessimistic as it sounds, I can't see it being to long before it really does happen

[Chris]

I think the same Cath we must be about due a big impact, it could be tomorrow or 10,000 years? I doubt we'll have much notice if we are still only tracking 1% of the sky.

[JamesF]

I'm not sure how to read that report. It says three earth radii and 19,000km as closest approach which is fine as I have 6400km in my head as a figure for the radius of the earth. But then it says the orbit of the International Play Station is one earth radius, but I know that's only about 370km high on average and that geosynchronous orbit is six Earth radii. I think they're actually talking about distance from the centre of the Earth as that would make the ISS and geosynchronous orbit figures correct, but it would mean that whilst the asteroid passed 19,000km from the centre of the earth, it would actually only be the Earth's diameter from actual impact.

Am I misreading something somewhere?

James

[JamesF]

Having read the comments, it looks like I'm not the only one who isn't sure what they mean.

James

[DirkSteele]

I can see where the confusion comes from, it is a poorly constructed sentence, though when thinking about the orbital distance of a satellite, it tends to be calculated from the centre of the earth (makes the maths easier). So the ISS for example orbits at just over 1 earth radii.

The video itself was pretty good. Seeing background stars wiz by really helped to show the true motion of the asteroid.