Looking for worlds in distant orbits is hard work. Sometimes, exoplanets can be directly imaged, but most of the time, our only hope for seeing worlds is to catch them crossing in front of their stars and blocking starlight in a way we can observe.
Today, this kind of discovery is the job of NASA’s Transiting Exoplanet Survey Satellite (TESS) which observes each spot for 27 days.
In order to confirm the presence of a planet, it needs to be seen transiting its star at least twice, and preferably three times. This means we can’t see planets like Earth or Venus or even Mercury because they all orbit too slowly. Often, TESS will pick up a single eclipse, telling us there is probably a planet out there, but these worlds are lost to us because no second eclipse (or third) is ever seen.
But now, there is one team trying to recover these lost worlds. The Next Generation Transit Survey (NGTS) in Chile is starting to follow up on lost worlds and a new paper in The Astrophysical Journal Letters documents their first discovery NGTS-11b, a warm Saturn that orbits every 35 days.
It’s a start – one lost world found – and we have a long way to go to see longer orbits. I don’t know when the tech will get there, but when it does, we’ll bring the discoveries to you here on the Daily Space.
“NGTS-11 b (TOI-1847 b): A Transiting Warm Saturn Recovered from a TESS Single-Transit Event,” Samuel Gill et al., 2020 July 20, Astrophysical Journal Letters (Preprint on arxiv.org)