Classification interface of the Hubble Asteroid Hunter (www.asteroidhunter.org) citizen science project. Individual users are asked to inspect HST image quadrants for asteroids and mark the beginning and end point of trails in the images. Markings from ten users are aggregated into a final classification. The asteroid trail is visible as a ‘C’ shape in the bottom right of the exposure. There are gaps in the trail as the displayed cutout is an HST composite exposure. The white arrow shows the position of the trail.