Astronomers have made the first ever observation from a ground-based telescope of a super-Earth passing in front of a star similar to the Sun. They used a moderate-sized instrument at the international observatory on La Palma, in the Canary Islands, to measure the tiny fade in light caused by the transit. The exoplanet, known as 55 Cancri e, was already known to exist. It orbits a star dimly visible to the naked eye called 55 Cancri, and was discovered from Texas in 2004, by detecting its effect on the star. But its nature was not properly understood until a few years later after it was studied by the MOST Space Telescope (it stands for Microvariability and Oscillation of Stars) which was designed and built in Canada, and NASA’s Spitzer space telescope. They showed it to be much smaller than the many gas giants known to orbit other stars. Its mass is about eight times that of our own planet and its diameter is twice the Earth’s, making it the first so-called super-Earth to be discovered. While transits of giant “hot Jupiters” have been monitored from the ground in the past, 55 Cancri e is very much smaller. Only one other super-Earth has been seen in transit from the surface of our planet, and that was orbiting a smaller and fainter red dwarf star. The fade of 55 Cancri e, which is the shallowest seen with a ground-based observatory, was recorded by a team using the 2.5-meter Nordic Optical Telescope on La Palma. It watched the starlight dim by just 1/2000th, or 0.05 per cent, over two hours. The planet 55 Cancri e is the innermost of five planets known to orbit the star, zipping around it in a year that is only 18 hours long. The planetary system is right on our cosmic doorstep, lying just 40 light-years away.