Free Astronomy Magazine July-August 2014

S PHERE shortly after being mounted at the Melipal focal plane. Clearly no- ticeable are some devices for cooling the instrument. [ESO/J. Girard] O ne of the last pha- ses before installing SPHERE, with a techni- cian performing final checks on some complex optical and electronic devices of the instru- ment. [ESO] SPHERE that limit now rises to 1 million times, giving researchers the opportunity to study the atmospheres of numerous plan- ets, especially gas giants – which are the main target of the new instrument – along with the gas and dust disks that surround many stars with planetary systems in forma- tion or, anyway, comparatively young. What makes SPHERE special is the combina- tion of several advanced techniques, aimed at achieving the highest possible contrast in a tiny region of the sky around the stars that host planets. One of the techniques deploy- ed by SPHERE is the extreme adaptive optics system, capable of correcting in a very effi- cient manner the distortions introduced in the images by the air masses moving in the Earth’s atmosphere. At the heart of the adap- tive optics system there is a deformable mirror which comprises 1300 actuators that can mod- ify the shape of the mirror (and hence the acquired image) at the rate of more than 1200