Earth. It was thought that the passage of G2 in 2013 might offer astronomers the chance to learn much more about how material accretes onto supermassive black holes. Several astronomical facilities observed this closest approach, with observations confirmed with Chandra, XMM, VLA, INTEGRAL, Swift, Fermi and requested at VLT and Keck. Simulations of the passage were made before it happened by groups at ESO and Lawrence Livermore National Laboratory (LLNL). As the cloud approached the black hole, Dr. Daryl Haggard said, "It's exciting to have something that feels more like an experiment", and hoped that the interaction would produce effects that would provide new information and insights. Nothing was observed during and after the closest approach of the cloud to the black hole, which was described as a lack of "fireworks" and a "flop". Astronomers from the UCLA Galactic Center Group published observations obtained on March 19 and 20, 2014, concluding that G2 was still intact (in contrast to predictions for a simple gas cloud hypothesis) and that the cloud was likely to have a central star. An analysis published on July 21, 2014, based on observations by the ESO's Very Large Telescope in Chile, concluded alternatively that the cloud, rather than being isolated, might be a dense clump within a continuous but thinner stream of matter, and would act as a constant breeze on the disk of matter orbiting the black hole, rather than sudden gusts that would have caused high brightness as they hit, as originally expected. Supporting this hypothesis, G1, a cloud that passed near the black hole 13 years ago, had an orbit almost identical to G2, consistent with both clouds, and a gas tail thought to be trailing G2, all being denser clumps within a large single gas stream. Professor Andrea Ghez et al. suggested in 2014 that G2 is not a gas cloud but rather a pair of binary stars that had been orbiting the black hole in tandem and merged into an extremely large star. See also List of nearest known black holes Notes References Further reading External links UCLA Galactic Center Group – latest results retrieved 8/12/2009 Is there a Supermassive Black Hole at the Center of the Milky Way? (arXiv preprint) 2004 paper deducing mass of central black hole from orbits of 7 stars (arXiv preprint) ESO video clip of orbiting star (533 KB MPEG Video) The Proper Motion of Sgr