Science Weekly podcast: Dark Matter, John Gribbin, a carrot mob, Nasa's Martian probe and Darwin's beard

This week's guest is astronomer and prolific author John Gribbin. We discuss dark matter and why the moon is so important. Plus, why the Earth, the universe and everything is rather pretty average really.

We chew over Charles Darwin's beard and why the Natural History Museum is missing a trick when it comes to merchandising.

Nanotechnology and Google Flu Trends get a mention too.

James Randerson reports back from The American Society for Reproductive Medicine in San Francisco. We speak to the man whose work has resulted in the birth of the first baby following an ovary transplant.

We meet a carrot mob in London's Covent Garden. They are trying to make businesses more energy efficient by using consumer power. A 'carrot' rather than a 'stick' approach.

And we have a, surprisingly emotional, tribute for Nasa's late great Martian probe, the Phoenix lander.

Another full studio with science correspondents Ian Sample and James Randerson, as well as Nell Boase from our arts desk.

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Thanks this week go to Charles Arthur, the Guardian's technology editor, for spending far too much of his time turning tweets into computer speech!