Exoplanets Explained: How Astronomers Find Worlds Orbiting Stars Beyond the Sun

The most mind-blowing discovery for astronomers has been planets around something that is not our star. Yet exoplanets are hard to observe directly, because the stars they orbit are so bright. Astronomers can't just go searching for the most over signs of life. They also have to look for the less obvious ones—like when a star's light dims or is jolted in its orbit by the planets looping around it. Those methods have subsequently found thousands of far-flung worlds and have suggested that there are worlds that orbit far outside the orbits of Earth, Mars, and Jupiter.

How NASA Detects Hidden Exoplanets Using Stellar Wobbles and Dimming Transits

As per a NASA report, one common technique involves spotting “wobbly” stars. A planet's gravitational tug shifts its star slightly off-centre, making the star appear to wobble from a distance. While the radial velocity method (discovers large planets like Jupiter) and the transit method (detects a drop in brightness in Earth-like planets) give size and orbit, and possibly indicate habitability.

In its 2009 Kepler mission, NASA detected planets of different sizes and distances from stars in various temperatures using the transit method, where 28 of them could be found within a habitable zone of a star where life could exist.

Astronomers have used transit timing to determine the distance of star and planet systems and have discovered a multitude of exoplanets, showing that planetary systems are common throughout the Milky Way.

NASA's TESS and other project missions are scanning the universe for other Earth-like planets and proving the existence of exoplanets, with many more patiently waiting to be found.