Proxima Centauri: The Nearest Planets
Around the closest star to the Sun orbits a roughly Earth-mass planet in the habitable zone — the nearest potentially habitable world, 4.24 light-years away.
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The nearest star to the Sun, Proxima Centauri, is a small red dwarf just 4.24 light-years away — and in 2016 astronomers found a roughly Earth-mass planet, Proxima b, orbiting it in its habitable zone.
It is the closest potentially habitable world we know of, which makes it the natural first target for any dream of reaching another star. The Breakthrough Starshot project imagines gram-scale light-sail probes crossing to it within a human lifetime.
The catch is the star itself: Proxima flares violently, and its habitable-zone planet — likely tidally locked — sits close enough to take the brunt, a serious threat to any atmosphere or life.
Proxima Centauri b was detected by radial velocity: a ~11-day signal implying a planet of at least about 1.1 Earth masses in the temperate zone of the M5.5 dwarf. A second, far lighter planet, Proxima d, was confirmed in the early 2020s on a tighter orbit — one of the lowest-mass planets known.
Proximity is the whole story. At 4.24 light-years the system anchors interstellar thought experiments, from Breakthrough Starshot's light sails to generations of science fiction, and is a priority target for future direct-imaging searches.
Habitability is genuinely uncertain. Red-dwarf flares, tidal locking, and the difficulty of confirming an atmosphere from Earth all keep Proxima b in the tantalising-but-unproven column — the nearest test case for whether red-dwarf worlds can be alive.
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