By C. J. De Mel, Jadetimes News
Beyond Earth's blue skies stretches a universe brimming with potential, including countless stars with planets that might support life. While Earth remains the only known host of life, astronomers have identified several exoplanets that could potentially support it.
"An exoplanet is a planet that orbits a star other than our Sun," explains Michelle Hill, an Earth and planetary science researcher at the University of California, Riverside.
A critical factor in assessing a planet's habitability is its location within the "habitable zone" or "Goldilocks zone" of its star. This region is where conditions are just right for life as we know it, allowing liquid water to exist on a planet's surface—not too hot and not too cold.
1. Proxima Centauri b
Distance: 4.24 light years away
Proxima Centauri b, the closest known exoplanet to our solar system, orbits within the habitable zone of the red dwarf star Proxima Centauri. With a mass of 1.27 Earths, it is classified as a super Earth, a type of exoplanet with a mass larger than Earth's but significantly less than that of gas giants like Neptune or Jupiter. Proxima Centauri b completes one orbit around its star in 11.2 days.
Researchers believe Proxima Centauri b might have a rocky surface, suggesting it could have the right conditions to support liquid water. However, it faces extreme ultraviolet radiation from its star, which can strip away its atmosphere and complicate its habitability.
2. TRAPPIST-1e
Distance: 39 light years away
TRAPPIST-1e is one of seven rocky exoplanets orbiting the cool dwarf star TRAPPIST-1. Discovered in 2017, this super Earth has a mass of approximately 0.69 Earths and takes 6.1 days to complete one orbit around its star. Its size and density suggest a rocky composition similar to Earth, raising the potential for it to support liquid water.
Despite its close proximity to its star, TRAPPIST-1e could maintain a stable climate due to the star's low energy output. Some studies even suggest TRAPPIST-1e might hold more water than Earth's oceans, making it an intriguing target for future research.
3. Kepler-186f
Distance: 500 light years away
Kepler-186f was the first Earth sized planet discovered in the habitable zone of another star. It receives about one third of the sunlight Earth does, suggesting it could have temperatures conducive to liquid water. Orbiting a red dwarf star, which typically has a longer lifespan than larger stars like our Sun, Kepler-186f might benefit from stable conditions for billions of years, providing a longer timeframe for life to potentially develop. Its likely rocky composition enhances its potential for habitability.
4. LHS 1140 b
Distance: 40 light years away
LHS 1140 b, another super Earth, resides in the habitable zone of its star. With a mass of about 5.6 times that of Earth, it likely has a rocky composition. This planet is believed to have a thick atmosphere, crucial for retaining heat, maintaining stable surface temperatures, and protecting potential liquid water from evaporating into space.
Orbiting a relatively quiet red dwarf star reduces the risk of harmful stellar flares. Recent studies suggest LHS 1140 b could be an ocean world with significant water content, increasing its potential habitability.
5. K2-18b
Distance: 124 light years away
K2-18b captured researchers' attention with the detection of water vapor in its atmosphere. Discovered in 2015, this exoplanet orbits within the habitable zone of its star. With a mass approximately 8.6 times that of Earth, K2-18b likely has a thick, hydrogen rich atmosphere, helping to retain heat and maintain stable conditions conducive to life.
Recent studies also suggest the presence of carbon bearing molecules like methane and carbon dioxide, supporting the hypothesis of a water ocean beneath this thick atmosphere.
6. Gliese 12 b
Distance: 40 light years away
Gliese 12 b orbits a cool, red dwarf star and takes 12.8 days to complete an orbit. The planet, about the size of Venus, might have temperatures around 107 degrees Fahrenheit, making it potentially temperate enough to support life.
Scientists are eager to study its atmosphere to understand how planets close to their stars retain or lose their atmospheres. The discovery of this “exo-Venus” may help scientists understand the habitability of planets orbiting cool stars in our Milky Way galaxy.
"Gliese 12 b represents one of the best targets to study whether Earth -size planets orbiting cool stars can retain their atmospheres, a crucial step to advance our understanding of habitability on planets across our galaxy," says Shishir Dholakia, an astrophysicist at the University of Southern Queensland, in a statement to the Royal Astronomical Society following the discovery of Gliese 12 b.
These six exoplanets are among the most promising candidates for hosting extraterrestrial life. As technology advances and we explore these distant worlds in greater detail, the possibility of finding life beyond Earth becomes increasingly tangible.
