So rather than falling through, they would simply fade away. Sadly, your friend would ultimately disappear because the black hole’s gravity makes it increasingly hard for their light to escape. Eventually they would be moving so slowly it would seem as if they were frozen in time. In fact, you would never see your friend fall into the black hole they would be continually moving towards it but forever slowing down. If you were to watch someone fall into a black hole, and say you could listen to their heart beat, you would hear it slow down as they neared the black hole. What would happen if I watched someone fall into a black hole?Ī black hole’s immense gravity slows down time. Many black holes were discovered in this way using the telescopes at Mt Stromlo, Canberra (before the bushfire of 2003). The star temporarily brightens, as the black hole moves by. When an “invisible” black hole passes in front of a distant star, its strong gravity bends the light from the star, shining it towards Earth. Quasars are incredibly bright because of their hot, gigantic accretion discs.Įven if a stellar black hole doesn’t have an accretion disc, astronomers have recently found a new way to find them. In the early 1960’s the Parkes Radio Telescope played a key role in showing that quasars are the unusually bright cores of a very distant galaxies, lying billions of light years away. The first supermassive black holes to be discovered are called quasars.

X-ray telescopes orbiting the Earth see this as a bright X-ray glow in the sky. The gas spirals down towards the black hole, forming a bright accretion disk. It is in orbit around a star and is pulling gas away from that star (like in the picture). The first stellar black hole, called Cygnus X-1, was found in 1971. This black hole pulls matter from blue star beside it. The gas in the accretion disk moves so quickly, and gets so hot, that it gives off X-rays, which can be detected by space telescopes.Īn artist's drawing a black hole named Cygnus X-1. Just as water spirals around a plug hole, gas and dust falling into a black hole circles around – forming an Accretion Disk – before disappearing across the event horizon. The easiest way to find a black hole is to watch something fall into it. Stay tuned for more!) If a black hole is invisible then how do you see one? (Recently some scientists, including Stephen Hawking, suggested that there may be a way for information to get out of a black hole. So if light cannot escape a black hole, then nothing else can either it is a hole in space. Why is a black hole a 'hole'?Įinstein says that nothing can travel faster than light. And with no light escaping, a black hole isn’t just black, it’s not even visible. The gravity at a black hole’s event horizon is so strong that light cannot escape its pull. Supermassive Black Holes, with a billion times the mass of the Sun, have event horizons that are three billion km wide or about as large as the orbit of Uranus. A Stellar Black Hole with the mass of five suns, has an event horizon around 30 km wide, about the size of Ballarat.

The greater the mass hidden inside the singularity, the larger the event horizon. To fully understand the singularity, scientists will need to combine two famous theories of the Universe: the General Theory of Relativity (that explains the very large) and Quantum Theory (that explains the very small). How a black hole can pack such huge amounts of matter into such a tiny space is a mystery. Anything that falls into the black hole is eventually crushed onto the singularity.

It is in this tiny spot that the entire mass of the black hole is contained.

The Singularity lies right at the heart of the black hole. However, using maths we can get an idea of what it might be like. Nothing can escape a black hole once it crosses the event horizon and we can never see what happens inside it. The event horizon is the point of no return. It is the closest thing a black hole has to a surface, but it’s not a physical surface – it’s an invisible bubble in space. The Event Horizon is the outer limit of the black hole. Black holes are really very simple as they have just two main parts – the Event Horizon and the Singularity.

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