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3 amazing random facts about space

Number 1

Matter

The elements hydrogen and helium make up 98 per cent of the matter we can see in the Universe. But there doesn't seem to be enough matter to account for the way stars and galaxies are pulled by gravity. As a result, astronomers think galaxies contain "dark matter", which we cannot see. There is also an unknown force making the Universe expand, known as "dark energy".

Number 2

Message sent to aliens

One of the biggest questions in science is whether life is unique to Earth or has arisen on other worlds. And if life has appeared elsewhere, could intelligent beings have evolved? Scientists have set up projects to watch and listen for signals from extraterrestrials, and messages have been sent to the stars to inform any aliens out there of our existence.
In 1974, scientists used the giant Arecibo radio telescope in Puerto Rico to broadcast a radio message towards the star cluster M13. The message contains symbols (right) that represent human beings, our base-10 counting system, the DNA molecule, and the Solar System. More a publicity stunt than a serious attempt to contacty aliens, the broadcast will take 25,000 years to M13, and a reply will take 25,000 years to return.

Number 3

The shape of space

The three dimensions of space are "bent" by the force of gravity from matter in the Universe into a fourth dimension that we can't see. This is hard to visualize, so scientists use the metaphor of a two-dimensional rubber sheet to explain the idea. The mass of the Universe could bend this rubber sheet in one of three ways, depending on how densely packed with matter the Universe is. Most scientists now think the shape of the Universe is "flat".