First Light Seen From Alien Planets

NASA’s Spitzer Space Telescope has captured the first direct light from two planets orbiting stars other than the sun.

Up to now, all confirmed extrasolar planets have been discovered indirectly, using either the wobble or transit method. That is, astronomers can detect a planet by the gravitational tug it exerts on its parent star, which makes the star wobble. Or, they can infer a planet’s presence when it passes in front of its star, causing the star to dim or blink.

Both strategies use visible-light telescopes and have revealed the mass and size of more than 100 extrasolar planets.

In the new data, however, Spitzer directly observed the warm glows of infrared radiation from the two hot Jupiters, as they are called. Hot Jupiters are extrasolar gas giants that zip closely around their parent stars, enough to heat their atmospheres to more than 1,340 degrees Fahrenheit.

Further Spitzer observations will use a range of infrared wavelengths to attempt to gather more information about the planets’ winds and atmospheric compositions, said mission controllers at NASA’s Jet Propulsion Laboratory.