Free Astronomy Magazine September-October 2019

35 SEPTEMBER-OCTOBER 2019 SPACE CHRONICLES Planets in the system (twice the size of Earth or bigger), would be de- tectable with the upgraded instru- mentation. The near- to thermal-infrared range is significant as it corresponds to the heat emitted by a candidate planet, and so enables astronomers to de- termine whether the planet’s tem- perature allows liquid water. Alpha Centauri is the closest star system to T his stunning image of the VLT is painted with the colours of sunset and reflected in water on the platform. While inclement weather at Cerro Paranal is unfortunate for the astronomers using it, it lets us see ESO's flagship telescope in a new light. [A. Ghizzi Panizza/ESO] our Solar System, at 4.37 light-years (about 25 trillion miles) away. It con- sists of two Sun-like stars, Alpha Centauri A and B, plus the red dwarf star, Proxima Centauri. Current knowledge of Alpha Cen- tauri’s planetary systems is sparse. In 2016, a team using ESO instruments discovered one Earth-like planet or- biting Proxima Centauri. But Alpha Centauri A and B remain unknown quantities; it is not clear how stable such binary star systems are for Earth-like planets, and the most promising way to establish whether they exist around these nearby stars is to attempt to observe them. Imaging such planets, however, is a major technical challenge, since the starlight that reflects off them is generally billions of times dimmer than the light coming to us directly