01-07-2014 07:00

Astronomers detected a mysterious signal. They picked it up in the Perseus Cluster, which is 240 million light years away from the Earth.

The scientists don’t yet know the origin of the signal. However, it is already the best evidence of dark matter. Astronomers believe that dark matter forms 85 per cent of the universe. It does not emit or absorb light like other things in space.

The detection of the signal excites people, but we need more data to prove dark matter exists.  

Difficult words: detect (notice), emit (to send out), absorb (take in).

You can read the original story and watch the video in the Level 3 section.