Venus Transit

Venus Transit

June 5 – 6, 2012

Photo Credit: NASA

Composite image of Mercury transit across the Sun, as seen by NASA's Solar Dynamics Oberservatory on Nov. 11, 2019. CREDIT: NASA's Goddard Space Flight Center

Mercury Transit

November 11, 2019

Photo Credit: NASA’s Goddard Space Flight Center


Outside our solar system, transits are used to search for planets (exoplanets).

Most known exoplanets have been discovered using the transit method. A transit occurs when a planet passes between a star and its observer. Transits reveal an exoplanet not because we directly see it from many light-years away, but because the planet passing in front of its star ever so slightly dims its light. This dimming can be seen in light curves – graphs showing light received over a period of time. When the exoplanet passes in front of the star, the light curve will show a dip in brightness.
The Webb Telescope is using this technique to search for planets.


How is NASA using transits today to find new planets orbiting distant Suns?