An exomoon is a moon that orbits a planet outside of our solar system, in another star system. The first exomoon candidate, Kepler-1625b-i, was discovered in 2017 by a team of astronomers led by David Kipping of Columbia University. However, it has not yet been confirmed as an exomoon.
There are two main methods for detecting exomoons: the radial velocity method and the transit method. The radial velocity method involves measuring the Doppler shift of the host star’s light as the planet and its moon orbit around it. This can be used to calculate the mass of the object orbiting the star (whether it be a planet or a moon). If this object is less massive than expected for a planet of its size, then it is likely that it is a moon. The transit method involves looking for slight changes in the timing or depth of planetary transits caused by an accompanyingmoon.
As of yet, there have been no confirmed exomoons found using either of these methods; however, there are several potential candidates that are currently being investigated. One such candidate is Kepler-1647b, which was discovered using the transit method. This candidate exomoon is estimated to be about 3 times the size of Earth’s Moon and orbits a Jupiter-sized planet located approximately 4000 light years away from Earth in the constellation Cygnus.
The search for exomoons is an ongoing one, and with new technology and improved observational techniques, it is only a matter of time until we find one (or many) orbiting another planet in another star system!