Have you ever wondered what Earth would look like if it was covered in lava? Well, you don’t have to imagine anymore, because astronomers have discovered a planet that is exactly that: a half-lava world.
The planet, named HD 63433 d, is the third to be found orbiting the star HD 63433 (TOI 1726), situated around 73 light years away from Earth. The planet is very young, only about 400 million years old, compared to our 4.5-billion-year-old world². It is also very small, only 1.1 times the diameter of Earth.
But what makes this planet so fascinating is its extreme temperature and rotation. HD 63433 d is tidally locked, meaning there is a dayside which always faces its star and a side that is constantly in darkness. This creates a huge contrast in temperature between the two hemispheres. The dayside of the planet can reach temperatures of about 2,294 Fahrenheit (1,257 Celsius), hot enough to melt rock and create a sea of lava. The nightside, on the other hand, is much cooler and probably solid.
Astronomy compels the soul to look upward, and leads us from this world to another.
– Plato
HD 63433 d is the smallest confirmed exoplanet younger than 500 million years old. It’s also the closest discovered Earth-sized planet this young². This makes it a valuable target for studying the formation and evolution of rocky planets, especially those that are close to their stars.
The discovery of HD 63433 d was made possible by NASA’s TESS (Transiting Exoplanet Survey Satellite), which spots “transits,” or instances where planets cross in front of their star as they orbit, blocking a tiny piece of the starlight. By analyzing the data from TESS, astronomers were able to detect the small dip in brightness caused by HD 63433 d every 4.2 days, which corresponds to its orbital period.
HD 63433 d is one of the many exotic worlds that TESS has revealed to us. The mission has already discovered over 2,000 exoplanet candidates, including some that are potentially habitable. With more data and observations, we can learn more about these distant planets and their diversity.
HD 63433 d may not be a place where we would want to live, but it is certainly a place where we would want to explore. It is a reminder of how amazing and diverse the universe is, and how much we still have to discover.
Source:
Discovery Alert: Earth-sized Planet Has a ‘Lava Hemisphere’. https://science.nasa.gov/universe/exoplanets/discovery-alert-earth-sized-planet-has-a-lava-hemisphere/.
