Black holes are incredibly strange phenomena: a collapsed star packed into a tiny region of space. Their gravitational force is so strong that not even light can escape.

So it is not surprising that, for a long time, black holes were not thought to actually exist – they were only a theoretical possibility.

But today, not only do we realise that black holes are relatively common in the universe, we also know that there are black holes lurking in the centre of all galaxies – including our own Milky Way Galaxy.

These black holes, called supermassive black holes, can pack the mass of millions or billions of suns into a region smaller than our solar system.

Tanya Hill spoke to Meg Urry, Professor of Physics and Astronomy at Yale University and currently the President of the American Astronomical Society, about distant galaxies and the supermassive black holes that can be found in their centre.

This podcast includes excerpts from Museum Victoria’s Black Holes: Journey into the Unknown, narrated by Geoffrey Rush.

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Music: Free Music Archive/Kai Engel - The Scope

Additional audio: Museum Victoria, Fox News (US), BBC Worldwide, Sky News (Australia)