However, that’s not quite been done with TIC 172900988b, whose mass and orbital properties are not yet confirmed.

“When a planet orbits a double-star system, transits of the same star don’t occur at consistent intervals,” said Haghighipour. “The planet might transit one star, and then transit the other, before transiting the first star again, and so on.”

Circumbinary planets take much longer to complete an orbit than the binary star. Since these exoplanet-hunters used data from TESS, that’s a problem, because TESS spends only 27 days looking at a sector of the night sky. Seeing three transits is unlikely.

So the researchers developed an all-new technique. “This planet’s orbit takes almost 200 days ... with the traditional transit method, we would have needed to wait over a year to detect two additional transits,” said Haghighipour. “Our new technique reduced that time to just five days, showing that despite its short window of observation, TESS can be used to detect circumbinary planets.”

TIC 172900988b was seen during two transits, one across each star, separated by just five days—so, critically, one less transit was needed to “see” it. “This discovery demonstrates that our new technique works and will be able to find many more planets,” said Haghighipour.

TESS is now in an extended mission after its prime mission ended in July 2020. So far it’s discovered 150 exoplanets with more than 4,500 candidates still to be confirmed.

Wishing you clear skies and wide eyes.