Galaxy Zoo began with a call for volunteers to help classify distant galaxies in space telescope images. The collaborative project made spectacular discoveries, spawning a family of similar projects - collectively known as the Zooniverse. We look back on 10 years of a citizen science phenomenon.
It started with a strange blue smudge on a computer screen.
Now that mysterious blob, spotted by a Dutch primary school teacher during a few idle hours one evening, has become one of the most remarkable recent discoveries in astronomy.
Hanny's Voorwerp, named after its discoverer Hanny van Arkel, is providing scientists with a striking new window on the universe.
They have found these distant clouds of glowing gas provide a kind of time capsule that can reveal what their neighbouring galaxies have been doing in the previous few thousand years.
For Miss van Arkel, it is fitting for the object that now bears her name to be providing such insights - it marks 10 years since she first encountered it during her summer break from teaching.
She had been taking part in a citizen science project called Galaxy Zoo, which asked members of the public to classify different types of galaxies from images taken by robotic telescopes.
