ESA Science & Technology - The stellar occultation technique at Venus

This animation shows the stellar occultation technique used by ESA's Venus Express mission to probe the atmosphere of Venus.

The stellar occultation technique allows astronomers to indirectly probe a planet's atmosphere by studying its influence on the light from distant stars. As it orbits the planet, the spacecraft's line of sight to a given star crosses the planet's atmosphere, meaning that starlight is prone to being absorbed by the atmosphere. By analysing how starlight is affected by the atmosphere, astronomers can infer various properties of the atmosphere itself, including its pressure and chemical composition.