On May 19 2009 the Space Shuttle Atlantis released the Hubble Space Telescope back into orbit after a hugely successful servicing mission. To mark the occasion, Mario Livio, one of the scientists involved in the mission and intimately acquainted with Hubble, takes stock of its scientific legacy.

When it comes to describing natural phenomena, mathematics is amazingly — even unreasonably — effective. In this article Mario Livio looks at an example of strings and knots, taking us from the mysteries of physical matter to the most esoteric outpost of pure mathematics, and back again.

Everyone knows what symmetry is, and the ability to spot it seems to be hard-wired into our brains. Mario Livio explains how not only shapes, but also laws of nature can be symmetrical, and how this aids our understanding of the universe.

It was Euclid who first defined the Golden Ratio, and ever since people have been fascinated by its extraordinary properties. Find out if beauty is in the eye of the beholder, and how the Golden Ratio crosses from mathematics to the arts.