Researchers have discovered the first Earthsized planet. It was first marked by 【1】(science) using NASA’s Kepler telescope (望远镜) ，so it’s called Kepler-186f. It lies about 500 light years from the Earth and goes【2】 its star. The planet is the right distance from its star for water： not too close and not too far. Water is one 【3】(importance) condition that scientists guess is necessary for life. So it could have water and possible life. It’s called a true Earth cousin.

“This 【4】 [‘plænɪt] is an Earth cousin,not an Earth twin ,” said Barclay,who is among a team of scientists reporting on the discovery in the magazine Science this week.

“It’s very 【5】(excited) to find a planet similar to the Earth”’ Barclay said. “It’s not easy work because things 【6】 [tʃeɪndʒ] as we get more measurements. ”

Scientists don't know anything about the air of Kepler-186f,but it will be a task for future telescopes that can study for chemicals that have something to do with life.

“It’s possible for 【7】 to live on this planet,but that doesn’t mean there is life on it ,” Barclay said.

So far,scientists have found nearly 1 ,800 planets in the 【8】

“The past year has seen a lot of【9】 [‘prəʊgres ] in the search for Earthlike planets. Kepler-186f is very important because it is the first planet that is the 【10】 temperature and is almost the same size as the Earth ,” scientist David Charbonneau wrote in an email.