Debra Fischer, a planet hunter from Yale, who was not part of the team, said, “This technological feat is incredibly important because it means that the detection of Earth-size planets at larger distances is technically possible.”

Kepler 20e, the closer and hotter planet, is also the smaller — about 6,900 miles across, or slightly smaller than Venus — and it resides about 5 million miles from its star. The more distant planet, Kepler 20f, also broiling at around 800 degrees, is 10 million miles out from its star. It is 8,200 miles in diameter, about the size of Earth. The two planets are presumed to be rocky orbs that formed in the outskirts of their planetary system and then migrated inward.

Their star, which is slightly smaller and cooler than the Sun, is about 950 light years away from us. Kepler had previously found three larger Neptune-like planets around it, so the new observations bring the total to five so far. All the planets are well inside where Mercury would be in our own solar system, presenting a bounteous system of unlivable planets.

“This is Venus and Earth in a five-planet system,” Dr. Fischer said in an e-mail. “There’s no place like home, and the Kepler data are starting to uncover some mighty familiar architectures.”

Kepler detects planets by watching for blinks when they move in front of their stars. Since it was launched in 2009, it has found 2,326 potential planets, 207 that would be Earth-size, if confirmed as the two reported Tuesday have been.

Confirmation of a planet, however, requires additional observations, usually of its star’s wobbles as it gets tugged by the planet going around. The gravitational pull of planets as small as the Earth on their parent star is too small to measure with the current spectrographs. And so the astronomers resorted to a statistical method called Blender, developed by Dr. Fressin and Guillermo Torres of the Harvard-Smithsonian Center, in which millions of computer simulations of background stars try to mimic the Kepler signal. They concluded that Kepler 20e was 3,400 times more likely to be a planet than background noise, while the odds in favor Kepler 20f being real were 1,370 to 1.