The wonder of old Mars and its sands

I miss old Mars. The Mars of imagination, the world with deep blue skies and red deserts filled with whatever magical societies and cities our whims desired. Real Mars is interesting too, and it’s there, and it’s what we’re going to have to deal with if we ever leave this planet. That Mars too can … More The wonder of old Mars and its sands

Is Comet Siding Spring going to turn our Mars probes into shredded tinfoil?

Shiver in your shoes, Martians! This month – specifically, 19 October at 18:28 Zulu – Comet C/2013 A1 ‘Siding Spring’ makes its closest approach to Mars. The nucleus, a few kilometres in diameter, will come a smidgeon under 120,000km from the red planet. That’s close. Though not as close as once feared. When the comet was … More Is Comet Siding Spring going to turn our Mars probes into shredded tinfoil?

Why is the sky blue? And other annoyingly rhetorical questions

I am often bemused by people who use ‘why is the sky blue’ as rhetoric – often to symbolise some question for which there is no answer. Actually there is an answer, and we’ve known it since 1871: ‘Rayleigh scattering’. It’s also why sunsets look red and orange. The effect is named after John William Strutt, … More Why is the sky blue? And other annoyingly rhetorical questions