The two planets, orbiting a star similar to our sun outside the solar system, are encouraging prospects of finding life outside Earth.
But they are too hot to contain life as we know it, with calculated temperatures of about 1,400 degrees and 800 degrees Fahrenheit, scientists said.
Since it was launched in 2009, NASA's planet-hunting Kepler telescope has found evidence of dozens of possible Earth-sized planets.
Dr. Ed Krupp, director of the Griffith Observatory, said the discoveries are possible because Keplar can see changes in light more minute than anything we've ever seen before.
"These planets, as they cross in front of their sun, are making the brightness of that star diminish a little bit," Krupp said.
The planets discovered Tuesday aren't the only ones making big news. One discovered a few weeks ago is also a topic of conversation.
Kepler 22b is the first confirmed planet believed to have a similar temperature to Earth - about 72 degrees - meaning it's possible water once existed there.
However, that planet is thought to be too big for life as we know it.
"What's bound to happen is the discovery of a planet the size of the Earth with the right temperature and the right zone, around the right kind of star," Krupp said.
The recent discoveries bring into focus that age old question: are we alone?
"I would be very sad to think there isn't something else out there," said LeVar Burton, actor on "Star Trek: The Next Generation," on a trip the Griffith Observatory on Tuesday. "It's exciting to contemplate what that might be and what value we might bring to that intelligence and what they might share with us."
The Associated Press contributed to this report.