The idea of giant black holes the size of the Solar System seemed more like science fiction that reality - such monsters would be so powerful that they could destroy the very fabric of the Universe. But in the last five years a series of discoveries has changed our understanding of supermassive black holes and galaxies forever. Using the powerful Hubble Space Telescope, scientists have been scanning nearby galaxies, searching for these giant black holes. So what scientists have been looking for is the effect of their massive gravity, hurling stars around them at immense speed. These giant agents of destruction appear to be common throughout the Universe.
Scientists now think supermassive black holes are a fundamental part of what a galaxy actually is.
Lurking at the heart of every single galaxy is a giant black hole of apocalyptic proportions - and that includes our own galaxy, the Milky Way. Astronomer Andrea Ghez has been studying the heart of the Milky Way for the last five years. A black hole that could destroy the entire Solar System. And as Horizon was filming in July 2000, Ghez got some terrifying images - of the giant monster sucking up gas and stars at the galaxy heart. These are questions that have been puzzling astronomers for the last few years - and in June, two separate groups of scientists found evidence that points to a startling answer.