Astronomers have for the first time measured the reflected light of planets outside our solar system, a breakthrough that could advance the search for habitable worlds in deep space.

Two teams of researchers announced their findings Tuesday on two Jupiter-size planets 153 and 489 light-years from Earth.

The planets, designated HD 209458b and TrES-1, are in the constellations Pegasus and Lyra. They are closer to their stars than Mercury is to the sun, making them too hot to support life.

The findings, made with the National Aeronautics and Space Administration’s Spitzer Space Telescope, are the first direct observations of alien worlds.

“I feel we’ve been blind and have just been given sight,” said Sara Seager of the Carnegie Institution, a member of one of the research teams.

The results will be published online today in the journal Nature and in the June issue of the Astrophysical Review.

The orbiting Spitzer telescope, launched in 2003, detects objects by measuring their infrared light — in essence, their heat.

About 150 extrasolar planets were first discovered through indirect means, by measuring the telltale wobble in the rotation of their stars or by spotting a tiny wink in the star’s light that occurs when the planet crosses in front of it. A third method involves measuring the bending of a star’s light waves to reveal the size of the planet.

The new breakthrough involves measuring the loss of heat and light when an orbiting planet disappears behind its star. By this means, the teams were able to calculate that the planets are being baked at temperatures up to 1,574 degrees Fahrenheit.

Because of this overheating, the planets have been nicknamed “hot Jupiters.”

Based on observations of the light spectrum, scientists determined the star being orbited by HD 209458b is very much like our sun. TrES-1’s star is smaller and cooler. Both planets complete one orbit every three days.

So far, scientists have not found small, Earth-like planets capable of hosting life. But some say they believe it’s just a matter of time before they will be able to detect habitable worlds.