Using three X-ray space telescopes - ESA's XMM-Newton, JAXA's Suzaku and NASA's Chandra - Japanese astronomers have discovered that the black hole at the centre of our galaxy was much more active 300 years ago, when it gorged on a large feast of nearby stars (for full details, see ESA's press release).

Imagine looking for a black object on a black background, and you will appreciate the difficulty in observing black holes! However, when a star or gas falls in towards a black hole, it...