Gaia's data is already an invaluable resource for astronomers and scientists. The mission was launched in late 2013 and now lies some 1.5 million km from Earth. With its two powerful telescopes and three science instruments, Gaia is creating the largest and most precise 3D map of the Milky Way. It does so by determining the position of its target stars and registering how they change throughout time.

So far, Gaia has measured 1.8 billion stars with unprecedented precision, the richest star catalogue to date. Gaia's third major data release, published in 2022, includes 10.5 million variable sources over the entire sky, identified using machine learning methods in a supervised classification scheme.

We have learned a great deal about the Milky Way as a whole too. Thanks to the mission, we now know our galaxy merged with another galaxy in its early life, around 10 billion years ago. We have also learned more about our neighbour galaxy, Andromeda, and how it will collide with the Milky Way billions of years from now.

Though Gaia's telescopes are incredibly powerful, researchers within the mission still need the help of the oldest visual tool on the planet: your eyes. In its almost 10 years since launch, Gaia has contributed massively to our understanding of the cosmos, and now you can take part in furthering the discoveries.

Within Gaia Vari, an ESA-funded citizen science project, you can help classify Gaia's variable stars — stars that change in brightness over time. These observations are key to better understand these celestial bodies better.

As analysing individual sources is beyond the scope of the Gaia consortium, you, as a citizen scientist will look over images and graphs to classify stars' brightness changes, colours, and other variables over time. You may also identify incorrect classifications made by the automated algorithms. This will help scientists organise and categorise what we know of the millions of stars Gaia has observed, toward the next Gaia data release in 2025. You may actually discover the most interesting stars!