Even though this story‘s old news by now I’m just listening to last week’s Mike Harding show on BBC iPlayer and it’s the last snippet of news before the show starts and as a story it really annoys me.

Astronomers calculate there is a tiny chance that Mars or Venus could collide with Earth – though it would not happen for at least a billion years.

Mars or Venus could collide with Earth. At its closest Venus is 41 million km from Earth, Mars about 56 million. Things are already looking a little suspect.

Writing in the journal Nature, a team led by Jacques Laskar shows there is also a chance Mercury could strike Venus and merge into a larger planet.

Professor Laskar of the Paris Observatory and his colleagues also report that Mars might experience a close encounter with Jupiter – whose massive gravity could hurl the Red Planet out of our Solar System.

Mercury is something like 50 million km from Venus on average (Mercury has the most eccentric orbit of any planet so it’s hard to say) and Mars is something like 550 million km from Jupiter. And this story is saying that one or more of these planets may at some point billions of years in the future collide with an adjacent planet. But it could go either way. As in Mars’s orbit could decay bringing it 50 million km closer or it could end up going about 500 million the other way. Wow. Glad to know we’re on this one.

The researchers carried out more than 2,500 simulations. They found that in some, Mars and Venus collided with the Earth

And I think we can assume that there are a few more than just these 2,500 outcomes. So what we’ve learnt is that in a billion years the orbits of the planets within our Solar System will have changed and as such there’s a very small chance that some of them may collide and/or get caught in each others gravity. The part that annoys me most is that this became a national news story – not that science research shouldn’t be news, it should, I’m just not sure something that’s not especially likely to happen and even if it does it won’t be for at least a billion years really counts.

In addition, I think if you’d’ve asked me to predict what was going to happen to the orbits of our planets in a billion years time I reckon I probably would’ve come up with outcomes along similar lines. I haven’t read the full article in Nature but I hope it has a bit more to it than was reported on.