NASA has discovered seven large Earth asteroids or liquid water outside the solar system.

HOUSTON, Feb. 22 (Xinhua) -- NASA held a press conference on the discovery of new major discoveries in exoplanet exploration.
astronomers have discovered that at least seven Earth-sized planets orbit a single star 40 light-years outside our solar system, three of which may contain liquid water and sustain life.
five scientists from related fields attended the launch, including Sara Siegel, an astrophysicist at the Massachusetts Institute of Technology who is a star on exoplanets, Michael Gillen, an astronomer at the University of Liege in Belgium, and a vice president of NASA's Science Mission Council.
findings were also published in the journal Nature on the same day.
NASA said the Spitzer Space Telescope confirmed and discovered the system of seven large Earth asteroids orbiting a single star, setting a new record for the largest number of livable belt planets found around a star outside the solar system.
all seven planets have life-supporting key factors under the right atmospheric conditions - liquid water, three of which are firmly in the livable zone have the highest chance of containing liquid water, and the surface may even have oceans.
the discovery could shed new life into the orbits of planets outside the solar system and help explore whether they exist.
"This is the first time that so many of these planets have been found orbiting the same star, and they are strikingly similar in size to Earth.
" paper's first author, Michael Gillen, said.
exoplanets have been found in tight structures near ultra-cold red dwarfs called TRAPPIST-1.
estimates from their mass that their surfaces are rocks, not gases like Jupiter's.
researchers believe that the planet TRAPPIST-1f is the best candidate to support the existence of life, it is slightly colder than Earth, but may be suitable for the atmosphere and enough greenhouse gases.
the system's planets are very close to each other, and if a person stands on the surface of a planet, one can see the geomorphological features and clouds of the neighboring planets.
the same side of these planets always faces the main star, so each side is permanent day or night, meaning that its weather patterns may be completely different from Earth's.
Thomas Zuboken, vice president of NASA's Science Mission Council, said the discovery could be an important jigsaw puzzle in the search for a livable environment and location conducive to life, giving new hope for humanity's search for a new world outside the earth.
the most exciting result in the Spitzer Space Telescope's 14-year run.
Sean Carey, manager of NASA's Spitzer Science Center, stressed, "Spitzer will follow up in the fall and, with the help of the Hubble and James Webb telescopes, further refine our understanding of these planets, assess key factors in their habitability, and reveal more mysteries."
" (Complete) Source: ChinaNews.com