How the Universe Works, Twin Suns: The Alien Mysteries

New discoveries are challenging what we know about black holes, with some astronomers even questioning if they exist. The latest science tries to explain how they work, and what they look like, even though no one has ever seen one.

Half of the star systems in our galaxy have two stars, possibly creating habitats for alien life. Here, binary stars fling entire worlds into space.

The solar system is different to others in the Milky Way, but it hides a violent past. Scientists examine the clues to reveal its secret history.

Quasars are the brightest objects in space, powered by black holes, and the most mysterious. How do they shape the universe, and ultimately aid in its destruction?

New research shows the migration of ice planets may have helped start life on Earth, and stopped it being destroyed. How are they so vital?

For four years, the Messenger space probe sent images of Mercury, the solar system's smallest planet, closest to the Sun. Could it threaten life on Earth?

Dwarf planets are some of the solar system's most active places, from oceans of liquid water on Pluto to vanishing volcanoes on icy Ceres.

Once thought to be an inevitable disaster, scientists now have the technology to prevent asteroids from hitting the Earth. How are they working to do this?

Space isn't as empty as it seems. It conceals a secret structure called spacetime - an invisible field that governs our lives.