William O. Balmer

In August 2024, the MIRI coronagraph on the James Webb Space Telescope stared at Alpha Centauri A, the nearest Sun-like star to our Sun. At 1.5 arcseconds from the star, a point source, S1, blinked into view. Flux: 3.5 mJy, contrast: 5.5×10⁻⁵. Four to six sigma. A lighthouse flashing in the fog.

130 light-years away, four giant planets orbit the young star HR 8799—each 5 to 10 times more massive than Jupiter. They lie far from the star, at distances from 15 to 70 astronomical units (one astronomical unit is the distance from Earth to the Sun).