Coin-sized camera spots distant planets express

Original: "Demonstrating Exoplanet Transit Photometry from Space with a 15-mm Aperture Optical Navigation Camera on Hayabusa2"
arXiv:2510.14229 · 2025-10-16 · CC BY 4.0 · 1 min
A 15 mm lens on the Hayabusa2 probe first spotted distant planets passing across their stars.

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The camera lens is no bigger than a quarter. You'd find it in a smartphone, but here it was mounted on the Hayabusa2 probe for asteroid landings. Yet scientists asked it to gaze afar (and the little thing pulled off the transit method (watching a planet cross its star's disk and slightly dim its light) for the first time, spotting exoplanets) worlds around other suns.

The camera caught the shadows of two scorching gas giants. Their passages caused brightness dips of mere fractions of a percent, like a chandelier's glow momentarily flickering as a mosquito flits by. By repeatedly capturing eclipses, astronomers stacked the signals and performed precise photometry (light measurement). One planet's orbital period had to be corrected — the discrepancy with earlier data was too large to ignore.

Usually, catching exoplanets demands telescopes with mirrors the size of swimming pools. Yet this coin, aimed right at the target and armed with clever software, managed to show them up.

This success proves you don't need giants to hunt for worlds. Sometimes a baby camera is enough. The real twist? The instrument was built for navigation during landing on asteroid Ryugu, not astronomy. Now miniature tools can blaze a trail to finding long-period planets that big surveys miss.

The ONC-T camera was originally built for navigation during landing on asteroid Ryugu — now it's snagged an astronomical record.

Scientists
Christian DopplerD. B. McLaughlinDidier QuelozMichel MayorR. A. RossiterDavid Charbonneau
Concepts
transit method tess subaru telescope kepler telescope transit exoplanet jwst exoplanet atmospheres JWST Hubble Space Telescope habitable worlds observatory exoplanets around red dwarfs neptune trappist 1 mercury erosita radial velocity direct imaging roman optical microscopy interstellar object