Maybe my kids should worry about 2009 BD – but I won’t

A color photograph of the Earth and Moon on De...

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Today is my eldest daughter’s 16th birthday. That means in April 2078 she will be a sprightly 82. I will, though, I am sure, be long gone at 112.

And, maybe she should be worried about 2009 BD, the 10 metre lump of rock that passes inside the Moon’s orbit this week – because on 29 April 2078 it is predicted to come very much closer – a mere 6000km or so.

And, then, in August 2087, when Eibhlin will be  92, it will come much closer still – about 2000km.

Of course these predictions are difficult to call accurate – as 2009 BD is so small and so close to both the Earth and Moon that its orbit is bound to be unstable. Eventually it is likely to collide with one of the two or be flung into a new orbit.

But perhaps that collision will come towards the end of this century. If it does it would not be a good idea to be under the rock – but on the other hand while the 7 kT (NASA’s JPL seems to have revised down its estimate from an earlier 18 kT) equivalent of TNT does bear comparison with a nuclear weapon it is a small one and one that would be “exploding” in the upper atmosphere most likely over an ocean.