Artist’s impression of the star S2 passing very close to the supermassive black hole at the centre of the Milky Way

This artist’s impression shows stars orbiting the supermassive black hole at the centre of the Milky Way. In 2018 one of these stars, S2, will pass very close to the black hole and this event will be the best opportunity to study the effects of very strong gravity and test the predictions of Einstein’s general relativity in the near future.

The GRAVITY instrument on the ESO Very Large Telescope Interferometer is the most powerful tool for measuring the positions of these stars in existence and it was successfully tested on the S2 star in the summer of 2016. The orbit of S2 is shown in red and the position of the central black hole is marked with a red cross.

Image Credit: ESO/L. Calçada
Explanation from: http://www.eso.org/public/images/eso1622a/