After decades of dreaming and preparation, scientists have finally put the Rosetta spacecraft into orbit around a comet. And now the Rosetta is about to land!

This is a breathtaking 'earthrise' viewed from the surface of the moon. NASA's Lunar Reconnaissance Orbiter sees the Earth rise 12 times a day but is usually so busy imaging the moon's surface it doesn't get to capture the moment. This colourised image was taken on 1 February 2014.

I learned about something called axial precession in astronomy class several years ago, which is the idea that as something rotates along its axis, it will slowly trace out a cone if the weight of the object isn't equally distributed. In the case of Earth, Earth isn't a perfect sphere as many of us may think it is -- it actually bulges out in the middle enough for it to allow this phenomenon to occur. At the time, all I really took from this concept was how fascinating it is for the north axial pole to move 1° every 72 years from where it is now, and complete one full cycle every 26 000 years. However, I never managed to understand how this concept could fit in to my understanding of why ice ages[1] occur, and why they too follow a specific ...