The search for another Earth has taken a big step forward, with the successful launch of NASA’s Kepler telescope. Riding a Delta 2 rocket, the telescope has two main tasks: to stare at the stars, and to stay still. Kepler can detect minute changes in the amount of light shining from the 100,000 stars it will watch. Some of those changes will be caused by planets passing in front of their parent suns, briefly blocking a little light. Kepler will hope to find Earth-like planets capable of supporting life – the so-called Goldilocks planets: not too hot, not too cold.