Free Astronomy Magazine September-October 2019

50 SEPTEMBER-OCTOBER 2019 SPACE CHRONICLES by ESO ESO contributes to protecting Earth from dangerous asteroids T he left-hand image shows SPHERE observations of asteroid 1999 KW 4 . The angular resolution in this image is equivalent to picking out a single building in New York — from Paris. An artist's impression of the asteroid pair is shown on the right. [ESO] and prepare the observing cam- paign. ESO joined the campaign with its flagship facility, the Very Large Tel- escope (VLT). The VLT is equipped with SPHERE — one of the very few instruments in the world capable of obtaining images sharp enough to distinguish the two components of the asteroid, which are separated by around 2.6 km. SPHERE was designed to observe ex- oplanets; its state-of-the-art adap- tive optics (AO) system corrects for T he International Asteroid Warning Network (IAWN) co- ordinated a cross-organisa- tional observing campaign of the asteroid 1999 KW 4 as it flew by Earth, reaching a minimum distance of 5.2 million km on 25 May 2019. 1999 KW 4 is about 1.3 km wide, and does not pose any risk to Earth. Since its orbit is well known, scien- tists were able to predict this fly-by the turbulence of the atmosphere, delivering images as sharp as if the telescope were in space. It is also equipped with coronagraphs to dim the glare of bright stars, exposing faint orbiting exoplanets.