The European Space Agency (ESA) is Europe’s gateway to space. Its mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world.
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During its in-orbit commissioning, ESA's Cheops mission observed the transit of KELT-11b in front of its host star.
HD 93396 is a subgiant yellow star located 320 light-years away, slightly cooler and three times larger than our Sun. It hosts a puffy gaseous planet, KELT-11b, about 30% larger in size than Jupiter, in an orbit that is much closer to the star than Mercury is to the Sun.
The light curve of this star shows a clear dip caused by the eight hour-long transit of KELT-11b, which enabled scientists to determine very precisely the diameter of the planet: 181,600 km – with an uncertainty just under 4300 km. The measurements made by Cheops are five times more accurate than those from Earth, providing a taster for the science to come from the Cheops mission.
In this graphic, the Sun is shown as a comparison, along with the diameter of Earth and Jupiter (calculated from the mean volumetric radius).
More information: Cheops observes its first exoplanets and is ready for science