This is something you hear said so often - that we risk being hit by an asteroid that could make humans extinct. But do we really? This is the article I’m commenting on, a recently breaking news story: Earth woefully unprepared for surprise comet or asteroid, Nasa scientist warns. Some are already worrying that it means that we are all due to die in the near future from an asteroid impact. Well, no, it doesn't mean that. So, what is the truth behind it? 

The source of all this is a comment by Dr Joseph Nuth who warns:

How can we predict the climate so far ahead when we can't do an accurate weather forecast even ten days ahead? Well it is remarkable that we can forecast our weather even one day ahead, and by looking at how the forecasters do that we can begin to understand how the models can work over longer timescales. When I was a child in the UK in the 1960s, with our unpredictable weather, a cautious person would take rain gear with them almost no matter what the forecasters said. Even as late as 1987 we had Michael Fish's famous weather blooper. This broadcast is so famous here that it starred in the Olympics 2012 opening ceremony.

Donald Trump has just been elected as US president, as a Republican climate skeptic. So if you are from the US you may get the impression that this is a political debate between “lefties” who think climate change is real and “righties” who think it isn’t. But it’s only in the US that there still is a political debate at all. Here in the UK for instance it has cross party support, and we have a right wing government who have just ratified the treaty. For us, it was a matter for debate a decade or two ago, but the debate was already over some years back. We've decided action is needed, and there were many things we could have done, but the main thing was to do something, and the Paris agreement was what they came up with.

"What area on Mars is the most interesting for us?". My answer to this question isn’t an impressive geological feature like Olympus Mons or Valles Marineres. For me, it’s a rather unremarkable seeming crater, Richardson crater near the south pole. Let me explain why.

First this shows where it is. It is close to the south pole - this is an elevation map and I’ve trimmed it down to the southern hemisphere. You can see Olympus Mons as the obvious large mountain just right of middle, and Hellas Basin as the big depression middle left. Richardson crater is about half way between them and much further south.

If Elon Musk and Robert Zubrin have their way, we may get migrations of hopefuls setting off from Earth to Mars to colonize what they believe to be a "New World". If so, what they find there will be far more like the nineteenth century Antarctica than the seventeenth century "New World". Indeed, even the climbers who tackled Mount Everest in the twentieth century explored a far more hospitable place than Mars. You could breathe the air on the summit with only the need for an oxygen mask. It's also bitterly cold on Mars - a night in the Martian tropics is colder than the coldest night on Everest in the middle of winter. It's so cold that the air often starts to freeze out as dry ice at night.

The recent crash of the ExoMars Schiaperelli lander on Mars highlights how difficult it is to land there. So why is that? Why are landings on Mars so complex? And why do they fail so often? ESA is getting somewhat bad press for this. In my view it validates the foresight of their approach, to send a test lander first. It also highlights the risk for manned missions to Mars and the planetary protection issues with humans to the Mars surface, which I've written about many times.