Weird Exoplanets
This is the text version of the interactive 3D documentary. 한국어
All exoplanets › Part 2: Inferno worlds
55 Cancri e
Rumored to be a diamond planet — it turned out to have a lava ocean
View in 3D · narrated- Distance
- 41 light-years (about 390 trillion km, 41 years at light speed)
- Type
- Super-Earth (rocky planet)
- Size
- About 1.9 times Earth’s width, about 8 times its mass
- Star
- 55 Cancri A (a little smaller than the Sun)
- Year (orbit)
- About 18 hours
- Temperature
- Day side above 1,500 °C (measurements differ)
- Found
- 2004
41 light-years, a neighbor in Cancer
55 Cancri e is about 41 light-years away, toward the constellation Cancer. Its star can just barely be seen without a telescope under a very dark country sky. The planet circles this star in 18 hours. Its whole year is shorter than one Earth day.
View this scene in 3D →A diamond planet?
In 2012, a team of researchers calculated that this planet holds a lot of carbon. Under huge pressure and heat, carbon turns into diamond. That led to the idea that much of the planet’s inside could be diamond. The screen shows that idea exactly as imagined.
Why?Pencil lead (graphite) and diamond are both made only of carbon. Deep underground, where the squeezing is strong and it’s very hot, carbon atoms lock tightly together into hard diamond.
Learn moreThe researchers said more than a third of the planet’s mass might be diamond. The story spread around the world as the “diamond planet.”
View this scene in 3D →What astronomers actually found: a lava ocean
Later measurements of the star showed less carbon than expected. The diamond-planet idea lost support. In 2024, the James Webb Space Telescope found signs that the surface is an ocean of molten lava, possibly covered by thick air.
Why?The planet orbits extremely close to its star, about 25 times closer than Mercury is to the Sun. So the day side is hot enough to melt rock.
Learn moreThe air may contain carbon monoxide or carbon dioxide, with gas constantly bubbling out of the lava to refill it. Exactly what the air is made of is still being studied.
View this scene in 3D →Sources: Wikipedia: 55 Cancri e
Distances and facts come from published research and NASA, as noted under each planet. The 3D close-ups are artist’s views based on that research, not photographs. Distances to faraway stars can carry some uncertainty.