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Daily Data InsightsThe number of identified exoplanets has dramatically increased thanks to the “transit method”

The number of identified exoplanets has dramatically increased thanks to the “transit method”

Exoplanets are planets that orbit stars other than the Sun. Their existence was first confirmed in 1992 when astronomers Aleksander Wolszczan and Dale Frail identified two exoplanets orbiting a star located 2,300 light-years from Earth.

As shown in this chart, from 1992 to 2005, scientists discovered two hundred more exoplanets. They primarily used a method called "radial velocity". This technique works by detecting small changes in the color of a star due to the gravitational pull of a planet orbiting it.

But starting in the mid-2000s, the "transit method” vastly accelerated the pace of exoplanet discovery. This method detects tiny dips in a star’s brightness when a planet passes in front of it. This dimming can reveal a planet's presence and provide information about its size and orbit.

As is often the case with technological change, what was once a unique scientific achievement has become a much more frequent occurrence. The advancements in detection methods now allow us to discover hundreds of exoplanets each year.

Adding up all methods of identification, more than 5,500 exoplanets have been found by scientists worldwide, according to data from NASA's Exoplanet Archive.

Browse more charts on astronomy and space exploration →

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