Incredibly light exoplanets with lower density than cotton candy discovered by NASA

Astronomers have discovered two colossal exoplanets, each roughly the size of Jupiter but with a density significantly lower than cotton candy, located 1,110 light-years away from Earth. These planets, designated TOI-791 b and TOI-791 c, represent the lightest celestial bodies ever found at their scale.

George Dransfield from the University of Oxford described the planets' densities as comparable to a "nice ball of shaving cream, fresh from the can." Their density is less than 0.05 grams per cubic centimeter, a stark contrast to Earth's density of 5.5 grams per cubic centimeter and Jupiter's, which is up to 35 times denser.

The discovery was made using NASA's Transiting Exoplanet Survey Satellite (TESS), which detects slight dips in a star's brightness as planets pass in front of it. TOI-791 b and TOI-791 c orbit a star in the Volans constellation. Researchers utilized ground-based telescopes to study their orbits and calculate their densities. Dransfield speculates the planets might be blue or white, depending on atmospheric cloud cover, and are likely composed primarily of hydrogen and helium.

These planets belong to a rare class known as "super-puffs." Out of nearly 6,300 confirmed exoplanets cataloged by NASA, fewer than 40 fall into this category. Scientists theorize that super-puffs form with massive hydrogen and helium-rich atmospheres around a solid core, which gradually dissipate over time, making them even lighter. The researchers believe TOI-791 b and TOI-791 c likely formed from the same gas and dust disk, earning them the designation of "siblings."