Astronomers have detected an Earth-sized exoplanet orbiting a Sun-like star relatively close to our solar system. Dubbed HD 63433 d, the planet is 73 light years from Earth and is believed to be roughly 400 million years old.^^1^^
Key Details About the Newly Discovered Exoplanet
HD 63433 d has a diameter only 10% larger than Earth’s and orbits its host star HD 63433 every 7.7 days.^^2^^ However, the planet’s surface temperature is estimated to be a scorching 1,480°C on average, hot enough to melt iron.^^3^^
Astronomers theorize that the extreme heat has created a hemisphere of the exoplanet that is perpetually covered in molten lava.^^4^^ This would make HD 63433 d the first observation of a terrestrial-sized lava world exoplanet.^^5^^
| Property | Value |
|---|---|
| Distance from Earth | 73 light years |
| Age | ~400 million years |
| Size relative to Earth | 1.1 times diameter |
| Orbit period | 7.7 days |
| Average surface temperature | 1,480°C |
The discovery was made by an international team using transit data from NASA’s TESS spacecraft and follow-up radial velocity observations by ground-based telescopes.^^6^^ The results have been published in two papers in Astrophysical Journal Letters and Monthly Notices of the Royal Astronomical Society.^^7^^
An Ideal Target in the Hunt for Habitable Worlds
HD 63433 d orbits a G-type main sequence star similar in size and temperature to our Sun.^^8^^ This makes the system a promising target in the search for potentially habitable exoplanets.^^9^^
The host star’s brightness allows scientists to study the exoplanet’s atmosphere when it passes in front of the star from our viewpoint – an event known as a transit.^^10^^ By analyzing starlight filtered through HD 63433 d’s atmosphere, the composition and other properties can be determined.^^11^^
Understanding planets like this one provides clues about the formation and evolution of worlds in the circumstellar habitable zones of Sun-like stars where liquid water could exist.^^12^^ While almost certainly inhospitable due to its great heat, HD 63433 d will improve models that guide the search for Earth 2.0.^^13^^
An Extreme Version of Tidally Locked Worlds
Like the Moon orbiting Earth, exoplanets very close to their host stars tend to become tidally locked so that one side permanently faces the star.^^14^^ HD 63433 d is likely tidally locked given its tight 7.7 day orbit.^^15^^
Being exposed to intense irradiation on only one hemisphere can create a sharp temperature gradient from dayside to nightside.^^16^^ On HD 63433 d, astronomers propose the dayside is hot enough for the surface to be entirely molten.^^17^^
This would represent an extreme case of tidally locked lava planets that have been predicted by models but not conclusively observed until now.^^18^^ Other examples may exist like the recently discovered ultra-hot Super Earth GJ 367 b which could have a dayside filled with lava oceans.^^19^^
First of Many More Worlds to Be Discovered
HD 63433 is part of the Ursa Major Moving Group, an association of stars with shared origins drifting together through space.^^20^^ Focusing on moving groups allows astronomers to target stars of known age to study how planetary systems evolve over time.^^21^^
The TESS mission is expected to detect over 1,000 exoplanets around nearby stars like HD 63433, ideal for detailed follow-up study by powerful telescopes such as James Webb.^^22^^ Astronomers are poised to characterize many worlds even more extreme than lava planet HD 63433 d in the years ahead.^^23^^
Each new discovery advances our understanding of planet formation processes and the odds of finding another habitable Earth analog that harbors life beyond our solar system.^^24^^ For now, HD 63433 d stands out as an exceptional lava-covered oddity begging for further scrutiny from astronomers worldwide.^^25^^
^^1^^ https://www.sci.news/astronomy/earth-sized-exoplanet-hd-63433d-12608.html
^^2^^ https://www.techexplorist.com/earth-sized-planet-lava-hemisphere/79634/
^^3^^ https://phys.org/news/2024-01-astronomers-earth-sized-planet-lava.html
^^4^^ https://www.universetoday.com/165216/half-of-this-exoplanet-is-covered-in-lava/
^^5^^ https://www.spacedaily.com/reports/Discovery_Alert_Earth_sized_Planet_Has_a_Lava_Hemisphere_999.html
^^6^^ https://astrobiology.com/2024/01/tess-hunt-for-young-and-maturing-exoplanets-thyme-xi-an-earth-sized-planet-orbiting-a-nearby-solar-like-host-in-the-400myr-ursa-major-moving-group.html
^^7^^ https://www.sci.news/astronomy/earth-sized-exoplanet-hd-63433d-12608.html
^^8^^ https://www.yahoo.com/news/newfound-earth-size-exoplanet-scorching-150024466.html
^^9^^ https://www.jpost.com/science/article-782104
^^10^^ https://www.digitaltrends.com/space/exoplanet-lava-hemisphere/
^^11^^ https://www.earth.com/news/new-earth-like-planet-discovered-in-big-dipper-constellation/
^^12^^ https://astrobiology.com/2024/01/tess-hunt-for-young-and-maturing-exoplanets-thyme-xi-an-earth-sized-planet-orbiting-a-nearby-solar-like-host-in-the-400myr-ursa-major-moving-group.html
^^13^^ https://www.techexplorist.com/earth-sized-planet-lava-hemisphere/79634/
^^14^^ https://www.digitaltrends.com/space/exoplanet-lava-hemisphere/?amp
^^15^^ https://www.universetoday.com/165216/half-of-this-exoplanet-is-covered-in-lava/
^^16^^ https://www.extremetech.com/science/astronomers-discover-earth-sized-planet-thats-half-lava
^^17^^ https://www.spacedaily.com/reports/Discovery_Alert_Earth_sized_Planet_Has_a_Lava_Hemisphere_999.html
^^18^^ https://arstechnica.com/science/2024/01/some-like-it-hot-astronomers-spot-an-earth-sized-exoplanet-thats-half-lava/
^^19^^ https://www.universetoday.com/165216/half-of-this-exoplanet-is-covered-in-lava/
^^20^^ https://astrobiology.com/2024/01/tess-hunt-for-young-and-maturing-exoplanets-thyme-xi-an-earth-sized-planet-orbiting-a-nearby-solar-like-host-in-the-400myr-ursa-major-moving-group.html
^^21^^ https://www.jpost.com/science/article-782104
^^22^^ https://www.techexplorist.com/earth-sized-planet-lava-hemisphere/79634/
^^23^^ https://www.universetoday.com/165216/half-of-this-exoplanet-is-covered-in-lava/
^^24^^ https://www.yahoo.com/news/newfound-earth-size-exoplanet-scorching-150024466.html
^^25^^ https://www.spacedaily.com/reports/Discovery_Alert_Earth_sized_Planet_Has_a_Lava_Hemisphere_999.html
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