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