Scientists added a record of 715 more planets to the list known to the world beyond the solar system, astronomers said on Wednesday, in February 2014. The additions include four planets about 0.5-2 times as big as Earth that are the right distance from their parent stars for liquid surface water, which is believed to be fit for life. The discoveries were made with the NASA's planet-hunting Kepler space telescope. The telescope, launched in 2009, spent four productive years observing 160,000 target stars for signs of planets passing by, within the telescope's sight. The numbers of planets announced at a NASA press conference on Wednesday increased Kepler's confirmed planets from 246 to 961. Combined with other telescopes' results, the total number of planets beyond the solar system now is nearly 1,700. "We almost doubled, just today, the number of planets known to humans," astronomer Douglas Hudgins, head of planet exploration at NASA Headquarters in Washington, told reporters on a conference call. Many planets' discovery is due to a new technique that analyzes potential planets in _ rather than one at a time. The method was developed after scientists realized that most planets, like those in the solar system, have similar worlds orbiting a common parent star. The newly found planets strengthen the evidence that small planets, two to three times the size of Earth, are common throughout the galaxy . "Generally, wherever (Kepler) can see them, it finds them," said astronomer Sara Seager, with the Massachusetts Institute of Technology. "That's why we have confidence that there will be planets like Earth in outer space." Like the solar system, which has eight planets plus Pluto and other so-called "dwarf planets," the newly found planets belong to families. But unlike the solar system's planets, which are about 150 times farther from the sun than Earth. Most of the planets fly nearer to their parent stars than Venus  orbits the sun, a distance of about 67 million miles (108 million km.) NASA and other space agencies are designing new telescopes to discover planets in so-called "habitable zones" around their parent stars where temperatures would be suitable for liquid surface water. Two papers on the new Kepler research will appear in an upcoming issue of 'The Astrophysical Journal'. Through Kepler, Scientists have found more planets   _   throughout the galaxy.
the same size as Earth about 0.5--2 times as big as Earth twice the size of Earth two to three times the size of Earth
Question: Scientists added a record of 715 more planets to the list known to the world beyond the solar system, astronomers said on Wednesday, in February 2014. The additions include four planets about 0.5-2 times as big as Earth that are the right distance from their parent stars for liquid surface water, which is believed to be fit for life. The discoveries were made with the NASA's planet-hunting Kepler space telescope. The telescope, launched in 2009, spent four productive years observing 160,000 target stars for signs of planets passing by, within the telescope's sight. The numbers of planets announced at a NASA press conference on Wednesday increased Kepler's confirmed planets from 246 to 961. Combined with other telescopes' results, the total number of planets beyond the solar system now is nearly 1,700. "We almost doubled, just today, the number of planets known to humans," astronomer Douglas Hudgins, head of planet exploration at NASA Headquarters in Washington, told reporters on a conference call. Many planets' discovery is due to a new technique that analyzes potential planets in _ rather than one at a time. The method was developed after scientists realized that most planets, like those in the solar system, have similar worlds orbiting a common parent star. The newly found planets strengthen the evidence that small planets, two to three times the size of Earth, are common throughout the galaxy . "Generally, wherever (Kepler) can see them, it finds them," said astronomer Sara Seager, with the Massachusetts Institute of Technology. "That's why we have confidence that there will be planets like Earth in outer space." Like the solar system, which has eight planets plus Pluto and other so-called "dwarf planets," the newly found planets belong to families. But unlike the solar system's planets, which are about 150 times farther from the sun than Earth. Most of the planets fly nearer to their parent stars than Venus  orbits the sun, a distance of about 67 million miles (108 million km.) NASA and other space agencies are designing new telescopes to discover planets in so-called "habitable zones" around their parent stars where temperatures would be suitable for liquid surface water. Two papers on the new Kepler research will appear in an upcoming issue of 'The Astrophysical Journal'. Through Kepler, Scientists have found more planets   _   throughout the galaxy.
A. the same size as Earth
B. about 0.5--2 times as big as Earth
C. twice the size of Earth
D. two to three times the size of Earth
Answer: