‘Spot the difference’ to help reveal Rosetta image secrets

Today, ESA and the Zooniverse launch Rosetta Zoo, a citizen science project that invites volunteers to engage in a cosmic game of ‘spot the difference’. By browsing through pictures collected by ESA’s Rosetta mission, you can help scientists figure out how a comet’s surface evolves as it swings around the Sun.

Rosetta spent over two years orbiting Comet 67P/Churyumov-Gerasimenko between 2014 and 2016. The spacecraft studied the comet up close, collecting unprecedented data to unlock some of the most intriguing mysteries surrounding the formation and evolution of our Solar System. Partway through Rosetta’s studies, the comet approached the Sun – a moment known as ‘perihelion’. Following its closest approach of about 186 million km from our star, the comet then moved away again. This meant that its surface was illuminated in different ways during the course of Rosetta’s mission.

Rosetta witnessed many landscape changes on Comet 67P: from the impressive fall of cliffs and the formation of pits, to evolving dust patterns and rolling boulders. Scientists are interested in using these changes to investigate the detailed mechanism through which a comet sheds its outer layers, as sunlight heats the ice and dust surrounding the nucleus.

The sheer number of surface changes, however, makes charting them a highly complex task. So scientists are looking for your help.