A giant exoplanet has just been confirmed about 400 light-years from Earth. Named TOI-4465 b, it stands out with a mass six times greater than Jupiter's and unusual orbital characteristics.
This planet takes 102 Earth days to complete one orbit around its star. It follows an elliptical orbit, which, combined with its orbital distance, keeps its temperature within a rather moderate range for a gas giant: between 93°C (199°F) and 204°C (399°F). These thermal conditions are unusual for this type of object, making it an interesting target for studying the formation mechanisms of giant planets.
An illustration of the new gas giant exoplanet TOI-4465 b.
Credit: Robert Lea (created with Canva)
Its initial detection came from data from the TESS satellite, designed to spot brightness dips caused by a planet passing in front of its star. But confirming TOI-4465 b required observing a second transit, often difficult to obtain for long-period planets.
This is where citizen science played a key role. Amateur astronomers from several countries contributed their observations at the crucial moment. Their personal instruments helped complete the missing data, an essential contribution given that professional observatories can't cover everything.
Exoplanets like TOI-4465 b, located in an intermediate zone between hot Jupiters and Neptune-type planets, are still rare. They could provide answers to lingering questions about the evolution of gas giants. More detailed analyses, particularly with the James Webb Space Telescope, are already being considered.
How do amateur scientists contribute to exoplanet discovery?
Complementing open data from missions like TESS, thousands of amateurs worldwide examine stars' light curves for variations typical of planetary transits. Their telescopes, often set up in their gardens or on balconies, allow monitoring of sky areas neglected by major observatories.
Animation of TOI-4465 b transiting its star, showing the corresponding brightness dip.
Credit: John Pickering
They're particularly useful for long-period planets, whose transits are rare and require constant vigilance. Collaborative platforms facilitate coordination and collective analysis, turning this scattered community into an effective observation network.
Why are long-orbital-period exoplanets so hard to detect?
The farther a planet is from its star, the less frequent and shorter its transits become. You need to be in the right place at the right time, with favorable weather and operational equipment. These constraints explain why such detections remain rare.
The case of TOI-4465 b illustrates this difficulty well. It took an international observation campaign and several months of patience to obtain solid confirmation. But the result is worth it: each discovery of this kind refines our understanding of planetary system diversity.