WASP-121b is so hot (4,600°F) that iron and magnesium escape into space.
Key Takeaways:
- Hubble discovered a football-shaped exoplanet, WASP-121b, leaking heavy metals like iron into space.
- This is the first time astronomers have seen heavy metals escaping a planet’s atmosphere.
- WASP-121b’s extreme heat (4,600°F) makes it puff up, weakening its gravity and causing material loss.
- Scientists believe hot Jupiters like WASP-121b migrate inward from cooler regions after formation.
- Future telescopes like James Webb will help study more lost materials around extreme exoplanets.
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Hubble Observes WASP-121b Leaking Iron and Magnesium
Astronomers using NASA’s Hubble Space Telescope have observed a rare and extreme phenomenon—an exoplanet so hot that even heavy metals are escaping its atmosphere. The planet, named WASP-121b, is about 900 light-years from Earth and has an upper atmosphere that is roughly ten times hotter than any other known exoplanet. The discovery, published in The Astronomical Journal, marks the first time scientists have observed heavy metals like iron and magnesium leaking from a planet into space.
Hot Jupiters, a class of gas giants similar in size to Jupiter but much closer to their stars, are known for their scorching temperatures. However, WASP-121b takes this to the extreme. It is heated to around 4,600°F (2,500°C), causing its outer layers to expand and weaken under the pull of its nearby star. This results in the planet taking on a stretched, football-like shape while actively losing material.
Astronomers detected this loss by studying how the planet and its escaping gases affect the light from its star during transits. Instead of directly seeing the planet, researchers analyzed changes in starlight as WASP-121b passed in front of its star. These observations confirmed that the escaping material included not just lighter gases like hydrogen and helium, but also much heavier elements—something never seen before in an exoplanet’s atmosphere.
A Glimpse Into Planetary Evolution
WASP-121b’s extreme heat challenges existing theories about planetary atmospheres. Typically, heavy metals remain condensed in a planet’s lower atmosphere, but this planet’s intense heat pushes them so high that they escape into space. This supports the idea that hot Jupiters may gradually lose mass over time, possibly leaving behind smaller, dense planetary cores.
Scientists also believe that hot Jupiters like WASP-121b did not form this close to their stars. Instead, they likely formed farther away in cooler regions and migrated inward. The fact that many hot Jupiters show signs of atmospheric loss supports this idea—some smaller planets orbiting close to stars might actually be the remnants of former hot Jupiters that lost their outer layers.
Future missions, including the James Webb Space Telescope, will allow astronomers to study even more extreme exoplanets and their atmospheres. These findings could help reveal how planets evolve under intense heat and what materials they might lose over time.
With WASP-121b, scientists have found a planet so extreme that even iron cannot hold on—offering a fascinating glimpse into how the universe’s hottest worlds change and evolve.
