[ti:N星和彩票A Observer Discovers Earth-sized World in ‘Habitable Zone’] [by:www.51星和彩票.com] [00:00.00]更多听力请访问51VOA.COM [00:00.04]A N星和彩票A satellite has discovered an Earth-sized world within its star's "habitable" area [00:08.48]-- where liquid water could possibly exist. [00:13.76]The world is known as an exoplanet. [00:17.60]This term is used for planets that orbit a star outside of our own solar system. [00:27.36]N星和彩票A's Transiting Exoplanet Survey Satellite, or TESS, made the discovery. [00:37.04]TESS was launched in 2018 to expand on the work of earlier exoplanets [00:44.60]that space telescopes had discovered. [00:48.96]Exoplanets are hard for telescopes to identify; [00:53.84]the bright lights of the stars they orbit can hide them. [01:00.00]TESS contains four individual cameras that search for drops in light levels. [01:07.72]This may be linked to planetary movements. [01:12.76]Scientists then attempt to confirm the presence of worlds [01:17.72]and try to estimate the size and orbit of the planets. [01:24.44]The newly found planet, called "TOI 700 d," [01:30.00]is about 100 light years away from Earth, N星和彩票A's Jet Propulsion Laboratory said. [01:39.16]It is about 20 percent larger than Earth. [01:43.24]TOI 700 d is one of three planets orbiting a star known as TOI 700. [01:54.48]The discovery was announced during a recent meeting [01:58.64]of the American Astronomical Society in Honolulu, Hawaii. [02:05.72]Being in a star's habitable area means that a planet has temperatures [02:11.96]that could permit liquid water to exist on the surface. [02:18.00]Since water is necessary for life as we know it, [02:22.32]the presence of liquid means it could possibly support life. [02:28.88]Astronomers have not yet been able to measure TOI 700 d's mass. [02:36.32]Such measurements will be necessary to estimate whether it is a rocky planet like Earth, [02:44.12]or a gassy one like Neptune. [02:48.76]Elisa Quintana is an astronomer at N星和彩票A's Goddard Space Flight Center in Greenbelt, Maryland. [02:58.44]She told Nature magazine that few Earth-sized planets have been discovered in habitable areas. [03:07.84]She says this makes the latest find "exciting." [03:13.32]Scientists say they confirmed the planet information using N星和彩票A's Spitzer Space Telescope. [03:22.96]They have modeled the planet's possible environments to help support future observation activities. [03:32.52]The modeling team for TOI 700 d is led by Gabrielle Engelmann-Suissa. [03:41.60]She is a visiting research assistant at Goddard. [03:46.84]She said in a statement that the modeling process is very important [03:52.16]to help learn more about conditions on TOI 700 d as more data is collected. [04:01.68]"It's exciting because no matter what we find out about the planet, [04:06.64]it's going to look completely different from what we have here on Earth," Engelmann-Suissa said. [04:15.44]Another exoplanet discovery was also discussed at the Astronomical Society meeting. [04:23.68]Scientists announced that TESS had found its first exoplanet orbiting two stars instead of one. [04:33.72]The planet is called TOI 1338 b, which lies about 1,300 light years away from Earth, N星和彩票A said. [04:46.20]It is about seven times larger than Earth. [04:50.00]That makes it between the sizes of Neptune and Saturn. [04:57.00]Astronomers have estimated that one of the planet's stars is about 10 percent more massive than our sun. [05:07.00]The other star is cooler, less bright and only one-third of our sun's mass. [05:14.72]The two stars orbit each other every 15 days. [05:20.76]These kinds of planets, called circumbinaries, are difficult to identify. [05:28.36]So far, scientists have confirmed about 24 of them. [05:34.08]The first such discovery came in 1993. [05:40.24]Overall, more than 3,500 exoplanets have been discovered over the past 20 years. [05:50.36]I'm Bryan Lynn. 更多听力请访问51VOA.COM