Scientists have found a potentially habitable(可居住的)planet and its star outside our Solar System are more similar to the Earth and our Sun than any other known planet-star pair. For now, the planet candidate(候选)is known as KOI-456.04. If its existence is confirmed by other telescopes, the planet would join a group of about 4,000 known planets outside our Solar System.
"It's the combination of its size less — than — double that of the Earth and its solar-type host star that makes it so special and familiar" Ren6 Heller, the lead author of the new study, said in a press release. That means it could potentially host life.
To be considered habitable, planets must orbit a stable star that keeps a temperature suitable for liquid water. The vast majority of identified Earth-like planets don't meet the conditions required for life to exist. They give off either too weak light or high-energy flames that can fry the planets around them. The star that KOI-456.04 orbits is about 1.1 times the size of the Sun, with a surface temperature of only 300 degrees Celsius less than the Sun. The star also sends out visible light, like our Sun does. Plus, KOI-456.04 is less — than — double the size of the Earth, which could mean its atmospheric conditions are similar to ours. If KOI-456.04 s atmosphere is like the Earths — meaning it has a mild greenhouse effect, then its average surface temperature would be about 5 degrees Celsius, compared to the Earth's average of 15 degrees Celsius, according to the Max Planck Institute.
The system is just over 3,000 light-years away from our Solar System. Future space telescopes could study the planet candidate further. NASA, the European Space Agency, and the Canadian Space Agency plan to launch(发射)the James Webb space telescope in 2021. The European Space Agency's PLATO space telescope, scheduled to launch in 2026, will focus on finding Earth-like planets orbiting Sun-like stars.
