Despite its approaching nine year birthday, the Spitzer Space Telescope, the Great Observatory designed to detect infrared light, is still making extraordinary discoveries. Roughly 41 light years away is the star 55 Cancri and around it orbits the planet 55 Cancri e, which was first discovered in 2004. Since then it has been closely studied by many observatories because it is a super-Earth, a planet larger than Earth but still smaller than a gas giant, like Neptune. Spitzer has pushed past the other observatories, with regards to this planet, by measuring the light directly emitted by planet, a feat never before accomplished with such a small exoplanet.
The planet-light was detected and filtered out from the sunlight by careful analysis of how the light changes when the planet moves behind the star. Even though stars will outweigh planets by several orders of magnitude, our observatories are sensitive enough to detect a change in light due to a planet transiting its parent star. After showing the dip in light was not some random occurrence, but the planet moving behind the star during its 18 hour year, the researchers were able to determine certain facts about it.
This super-Earth has a radius roughly double that of Earth's, while also being eight times as massive. The temperature of the sun-facing side of the planet is at an almost-hellish 2000-2360 K, or 3140-3700 ºF. Steel melts at a lower temperature.
As amazing an achievement as this is, we can expect still more amazing ones in the future. By proving it can be done, more observatories will seek to replicate Spitzer's success, including the upcoming James Webb Telescope. Though often touted as the replacement for the Hubble Space Telescope, the James Webb Telescope will have very limited visible-light capability with spectacular near-infrared abilities. This is because infrared light is often more useful to astronomers.