How planets are found.
And how SetuHQ finds them.

15 chapters, each an animated explainer with its physics and sources. Every drawing says whether it is an illustration, a model from stored values, or real data, and by how much it is exaggerated. Only the transit chapter is something SetuHQ itself does.

Chapter 1 of 15

How a survey works

A survey points a camera at many stars at once and measures each one's brightness again and again. Most stars never show a planet. Only planets whose orbits happen to line up with us can cross their star's face.

Illustration
A star field. Reticle rings lock onto stars one at a time, as a survey checks each target. Each locked star shows whether its imagined planet's orbit lines up with us; about one in thirteen do for a pi Men c-like orbit. Star colours follow each star's temperature.

Why only a few transit

A planet transits only if its orbit is aligned closely enough with our line of sight. For random orientations the chance is about R★/a, the star's radius over the orbit's size (Winn 2010). Close-in planets around large stars transit more often.

QuantityValueFrom
Chance pi Men c's orbit transits7.6%R★/a from exoplanet.eu R★ = 1.1 R☉, a = 0.06702 AU [calc]
Chance an Earth–Sun orbit transits0.47%R☉/1 AU, IAU nominal values [calc]
Sky TESS had observed by 18 Oct 202697.8%computed with tess-point (the Galaxy's coverage panel)

SetuHQ reads TESS light curves: one star at a time, about 27 days per sector. See TESS's sky coverage ›

Planets in this chapterpi Men c ›
Sources

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