Dive into fresh CHEOPS light curves! Your classifications are needed now to hunt for shallow transits and multi-planet systems. Every dip you spot brings us closer to finding Earth-like neighbors. Start classifying today!
Research
Planet Hunters CHEOPS invites you to help explore thousands of light curves observed by ESA’s CHEOPS space telescope.
CHEOPS was designed to study planets around other stars. During its first five years in space, it also observed many background stars that happened to fall in the same images as its main targets. These stars were not the original focus of the observations, but they may still contain valuable scientific surprises.
In this project, we are opening around 27,000 public light curves from these background stars of all the observations and asking volunteers to help us look for interesting features. We are showing them alongside light-curves from the targeted exoplanet systems, in the middle of the images, to teach volunteers what transiting exoplanet light curves look like.
A light curve is a graph that shows how the brightness of a star changes over time. Most stars look fairly steady, but some show dips, flares, waves, or other patterns. By looking carefully at these light curves, you can help us identify signals that computers may miss or struggle to classify.
What are we looking for?
We are especially interested in features such as:
- Transit-like dips: small decreases in brightness that could happen when a planet passes in front of a star.
- Flares: sudden increases in brightness caused by energetic activity on a star.
- Periodic variability: repeating patterns that may reveal rotating stars, pulsations, or eclipsing systems.
- Eclipsing binary stars: two stars orbiting each other and passing in front of one another.
- Unusual or unexpected features: anything that looks interesting, strange, or difficult to explain.
Not every dip is caused by a planet, and not every unusual light curve will lead to a discovery. But every classification helps us separate ordinary cases from the most interesting ones.
Why do we need your help?
CHEOPS has produced a rich collection of observations. While automated tools are very useful, the human eye is still excellent at spotting patterns, odd shapes, and surprising details.
Citizen scientists can help us by:
- finding a new exoplanet transit-like feature in a star that was not known yet to have an transiting exoplanet,
- identifying other promising light curves,
- separating real-looking signals from noise or instrumental effects,
- spotting rare events,
- highlighting unusual cases for expert follow-up,
- helping us understand how much hidden science is present in CHEOPS background-star data.
Your classifications will help the science team build a ranked list of interesting candidates for further investigation.
Could this lead to new planet candidates?
Possibly.
Some light curves may contain transit-like signals, which are the kind of dips we expect when a planet crosses in front of its star. However, many things can create similar-looking features, including other stars, instrumental effects, or random noise.
For this reason, we call them candidate signals until they have been carefully checked. If volunteers identify strong candidates, the science team will compare them with other data and investigate whether they could be genuine astrophysical events.
Even when a signal is not caused by a planet, it may still be scientifically valuable. Variable stars, flares, eclipsing binaries, and unusual stellar behaviour can all teach us something about the stars observed by CHEOPS.
What is CHEOPS?
CHEOPS, the CHaracterising ExOPlanet Satellite, is a space telescope from the European Space Agency. Its main mission is to observe stars that are already known to host planets and measure tiny changes in their brightness with very high precision.
These brightness changes can tell us about the size, orbit, and sometimes even the environment of planets beyond our Solar System.
Planet Hunters CHEOPS uses an additional part of the CHEOPS data: the background stars captured in the telescope’s images.
What happens after you classify?
Each light curve will be seen by several volunteers. We will combine the classifications to find the cases with the strongest agreement.
The science team will then:
- review the most interesting light curves,
- check whether the features are likely to be real,
- compare them with known stars and catalogues,
- identify the best candidates for further study,
- share updates with the volunteer community.
Your work helps us decide where to look more closely.
Why this project matters
Space telescopes often collect more information than can be fully explored by the original science programme alone. By studying CHEOPS background stars, we can increase the scientific value of the mission and possibly uncover signals that were not the original target of the observations.
Planet Hunters CHEOPS is also a way to bring the public directly into the process of scientific discovery in a research area that is tremendously exciting and active at the moment. Whether you classify one light curve or hundreds, your contribution helps us explore the hidden potential of CHEOPS data and possibly uncover new exoplanet candidates in our dataset that have not been discovered yet.
Thank you for joining the search.