The World, the Universe and Us Astronomers Stunned by a Tiny World With an Atmosphere
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May 6, 2026 
James Woodford, science reporter who unpacks the surprising atmosphere found around Kuiper Belt object 2002 XV93. Jacob Aron, science editor and planetary reporter who revisits the Pluto classification debate. They describe the occultation that revealed a whisper-thin atmosphere, puzzling sources like outgassing or impacts, and how this finding rekindles questions about what we call a planet.
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Tiny Plutino Carries Surprisingly Detectable Atmosphere
- A tiny 500 km Kuiper belt object 2002 XV93 (a plutino) shows a detectable atmosphere despite being far too small to ordinarily retain one.
- An occultation observed from Japan produced a 1.5 second dimming delay implying an atmosphere 50–100× thinner than Pluto and millions of times thinner than Earth's.
Two Plausible Sources For The Tiny Atmosphere
- The atmosphere could be transient or replenished; researchers propose either ongoing cryovolcanism or a recent impact as sources.
- If transient, the chance of catching it during a single occultation is small, making detection puzzling.
Why Pluto Lost Planet Status In 2006
- The IAU planet definition requires orbiting the Sun, hydrostatic equilibrium (roundness), and clearing the orbital neighborhood.
- Pluto meets the first two but fails criterion C, which is why it was reclassified as a dwarf planet in 2006.