First glimpse of planets from Earth

TWO separate teams of scientists reported on Wednesday the first-ever detection from Earth of the atmosphere of planets outside our solar system.

Taken together, the studies open a new frontier in the study of exoplanets, hard-to-detect celestial bodies circling stars beyond our own solar system.

Barely 300 exoplanets - some of which may have conditions similar to those that gave rise to life on Earth - have been identified so far, though astronomers assume that far more are waiting to be discovered.

Up to now, virtually everything known about the atmosphere of exoplanets has come from data collected by the space-based Spitzer infrared telescope.

But Spitzer will soon run out of the cryogens needed to keep its instruments cool, severely limiting its capabilities.

One team spotted a massive planet many times the size of Earth named OGLE-TR-56b, a so-called "hot Jupiter."

Hot Jupiters are massive planets - many times the size of Earth - that orbit very close to their stars. Because they are so near, they are believed to be hot enough to emit radiation in optical and near-infrared wavelengths that would be visible from Earth.

"The successful recipe is a planet that emits a lot of heat and has little-to-no wind in its atmosphere," said co-author Mercedes Lozez-Morales of the Carnegie Institution in Washington DC.

In addition, it must be a clear and calm night on Earth in order accurately measure the differences in thermal emissions when the exoplanet is eclipsed as it goes behind the star.

"The eclipse allows us to separate the emissions of the planet from those of the star," she said in a statement.

Two observations of OGLE-TR-56b were made last summer, one using the European Southern Observatory's Very Large Telescope, and the other using Carnegie's own Magellan-Baade telescope, both in Chile.

"The planet is glowing red-hot like a kitchen stove burner," said lead author David Sing of the Paris Astrophysics Institute.

"But we had to know precisely when the eclipse was going to happen and measure the stellar flux very accurately so it could be removed to reveal the planet's thermal emission," he said.

In the other study, also to be published in the Paris-based journal Astronomy and Astrophysics, astronomers in the Netherlands detected thermal emissions from another exoplanet names TrES-3b.