On the 25th of March 2022, NASA Exoplanet Archive confirmed the existence of the 5,000th exoplanet. Although none of these exoplanets are qualified to be Earth 2.0, they are more or less “small, rocky worlds like Earth,” and “gas giants many times larger than Jupiter” claimed the officials from Jet Propulsion Laboratory (JPL). NASA’s $10 billion investment in the James Webb Space Telescope has enabled more exoplanets to be discovered across the universe. Additionally, China has announced plans for their Earth 2.0 mission to find a habitable exoplanet in the Milky Way.
Jessie Christiansen, the archive’s lead, said 5,000 is “not just a number. Every one of them is a new world.” The first discovery of a new star named QB1 was dated back in 1992 and was discovered by astronomers David Jewitt and Janet Luu. They used a 2.2-metre telescope to detect the existence of another solar system. As technology advances, scientists use other measures such as the transit method to confirm the passing of a planet over a star.
This method was first introduced by astronomer William Borucki, who decided to attach sensitive light detectors onto a telescope and launch it into space. According to JPL, “the telescope would stare for years at a field of more than 170,000 stars, searching for tiny dips in starlight when a planet crossed a star’s face.” Other than indicating the dimming of stars, gravitational lensing is also adopted to find exoplanets. This alternative method allows scientists to track “slight back-and-forth motions of a star, caused by gravitational tugs from orbiting planets.”
China’s Earth 2.0 mission hopes to incorporate satellite analysing methods. A satellite is expected to be built by 2026 and will be funded by the Chinese Academy of Sciences. This satellite will carry seven telescopes and six of them will observe the dimming of stars in the Cygnus-Lyra constellations. This mission is “an opportunity for better international collaboration,” said Jian Ge, the leading astronomer of the mission. NASA believes the best-known world is the TRAPPIST-1 system. First discovered by astronomer John Gizis, the system was noted as having an “ultra-cool dwarf star” accompanied by three planets. However, in 2017 astronomers corrected this information to seven planets and proposed TRAPPIST-1 being an older system than ours, ageing 5.4 to 9.8 billion years old.