It did not seem to matter that the planets -- rocky masses, with one about the size of the moon and the other two a bit bigger than Earth -- were orbiting the remains of a giant star that exploded then condensed into a super-dense, rapidly spinning mass about the size of Manhattan Island, so therefore there was virtually no chance they could support life. What did matter was that astronomers were able to identify them.

Soon thereafter, exoplanet discoveries became routine, to the point where so far there have been nearly 150 confirmed, circling stars in the galactic neighborhood.

Astronomers have become good at detecting them using two tried-and-true methods, nicknamed wobble and blink. The wobble method can detect a planet from the gravitational tug it exerts on its parent star, which makes the star wobble.

They also can infer a planet's presence when it eclipses its parent as it passes in front, causing the star's brightness to dim, or blink, during the transit period.

Now, astronomers have added a third and maybe more dramatic approach. As reported in Thursday's edition of the British journal Nature, a team using NASA's new Spitzer Space Telescope actually has captured light directly from a pair of previously known exoplanets with the spacecraft's infrared-light-sensitive instruments.

Two teams of researchers pinpointed the planets, both within the Milky Way. The first, cataloged as HD 209458b, is orbiting a star about 150 light-years distant -- also in Pegasus. The second, designated TrES-1, is nearly 500 light-years away in the constellation Lyra.

Spitzer directly observed the warm infrared glows of the two planets, known as hot-Jupiters. Though the real Jupiter lies half-a-billion miles from the sun and is quite cold, its hot namesakes orbit closely around their parent stars -- where they absorb considerable heat and therefore radiate brightly in the infrared wavelengths.

Though Spitzer could not capture images of the two gas giants, the researchers used what they called a simple trick to distinguish the planets' radiant glow from the light of their stars.

First, Spitzer collected the total infrared light from each star-planet combo. Then, when the planet dipped behind the star during its orbit, the astronomers measured the infrared light coming from just the star. This pinpointed exactly how much infrared light belonged to the planet.

The data collected showed that the surfaces of both planets would be hugely inhospitable to life as we know it. HD 209458b, for example, registered a searing 1,130 degrees Kelvin, or 1,575 degrees Fahrenheit. Even on hothouse Venus, the surface temperature is a relatively tepid 900 degrees F.

Granted, like the Pegasus trio, the two hot-Jupiters represent planetary extremes, and poor candidates for living organisms, not to mention intelligent beings.

Still, the discoveries mark a step forward in the search for other worlds, an effort for which Spitzer has turned out to be surprisingly well-suited -- at least, in the case of exoplanets that transit stars located within about 500 light-years of Earth.

The interesting thing is that the Spitzer was not originally designed to see extrasolar planets. That task was supposed to go to NASA's Terrestrial Planet Finder.

Set to launch in 2016, the pair of high-orbiting telescopes are designed to capture direct images of exoplanets as small as Earth. With the two discoveries, however, Spitzer might help bridge the next 15 years, until TPF becomes fully operational.

"This first detection of light from two confirmed extrasolar planets is another major milestone along the way to the ultimate goal of finding Earth-like planets and examining their atmospheres for signs of life," said Alan Boss, a star and planet-formation theorist at the Carnegie Institution and an exoplanet adviser to NASA.

"This detection means that we are succeeding in the effort to combine astronomy and biology into the new field of astrobiology, which seeks to determine if life has originated and evolved elsewhere in the universe."

Sara Seager, also with Carnegie and the co-author of the research, put it more succinctly. "I feel we've been blind and have just been given sight," she said. "Detecting light from these other worlds ... opens a whole new window on these objects. It's the beginning of our ability to study their temperature and composition."

That is exactly the point. Even if it does not detect any more planets, Spitzer represents an interim step in the development of techniques to glean useful information about possible habitable worlds from incredibly vast distances.

Collecting a wisp of infrared light might not seem like much, but as technology progresses, astronomers eventually will be able to dissect that light into its constituent wavelengths. That means at some point they will begin to be able to determine exactly what makes up an alien planet's atmosphere.

When a reading comes back indicating about 80 percent nitrogen and 20 percent oxygen, we have found our first candidate for a neighboring biosphere.

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