Skies to Stars - June 2012

By Ed Downs

This month’s edition of Skies to Stars diverts from the personal experience of astronomy and takes a quick trip into the wonders of astrophysics.  The big guns at NASA are coming up with some pretty cool stuff that has been shaking up the scientific community.  From almost the beginning of recorded time, our feeble species has wondered, “are there other ‘Earths’ out there?”  Thanks to the Kepler, the Spitzer Space Telescopes and the U.S. portion of the European Space Agency’s Planck mission, that question is being answered. 

The Kepler Space Telescope looks for Earth-size planets in the habitable zone, the region in a planetary system where liquid water could exist on the surface of the planet orbiting around sun-like stars in our galaxy. The Spitzer Space Telescope provides the astronomical community with unique infrared images. Among its many duties is probing the atmospheres of planets beyond our sun. The bottom line is that over 2,300 “planet candidates” have now been discovered.  Some 400 of these planet candidates are presumed to be “Earth-like,” in that they are estimated to be similar to Earth size and in a favorable temperature zone that will support liquid water.  One of these candidates, Kepler 22b, is of particular interest and is known to occupy a habitable zone.  But the following information from a NASA press release is even more exciting because a planet, called 55 Cancri e, has been detected by the presence of its own light.

“NASA’s Spitzer Space Telescope has amazed us yet again,” said Bill Danchi, Spitzer program scientist at NASA Headquarters in Washington. “The spacecraft is pioneering the study of atmospheres of distant planets and paving the way for NASA’s upcoming James Webb Space Telescope to apply a similar technique on potentially habitable planets.”

The planet, called 55 Cancri e, falls into a class of planets termed, “super Earths,” which are more massive than our home world. The planet is about twice as big and eight times as massive as Earth. It orbits a bright star, called 55 Cancri, in a mere 18 hours. Previously, Spitzer and other telescopes were able to study the planet by analyzing how the light from 55 Cancri changed as the planet passed in front of the star. In the new study, Spitzer measured how much infrared light comes from the planet itself. The results reveal the planet is likely dark in appearance, and its sun-facing side is more than 2,000 Kelvin (3,140 degrees Fahrenheit), hot enough to melt metal.  The new information is consistent with a prior theory that 55 Cancri e is a water world: a rocky core surrounded by a layer of water in a “supercritical” state where it is both liquid and gas, and topped by a blanket of steam.

The 55 Cancri solar system is relatively close to Earth, at 41 light-years away. It has five planets, with 55 Cancri e the closest to the star. Spitzer discovered the sun-facing side is extremely hot, indicating the planet probably does not have a substantial atmosphere to carry the sun’s heat to the unlit side. “When we conceived of Spitzer more than 40 years ago, exoplanets (distant solar systems) hadn’t even been discovered,” said Michael Werner, Spitzer project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Because Spitzer was built very well, it’s been able to adapt to this new field and make historic advances such as this.” In 2005, Spitzer became the first telescope to detect light from a planet beyond our solar system. Since then, other telescopes, including NASA’s Hubble and Kepler space telescopes, have performed similar feats of observation. NASA is now learning how to observe the planets themselves, and applying that knowledge to other space telescopes.  

But, is this advance stuff just for the pros.  Not at all.  While the amateur astronomer can not see exoplanets, we can view variable stars, and see the star systems that contain active solar systems.  We can see the same galaxies being seen by these advanced telescopes and, through amateur astro-imaging (photography), obtain remarkable records of our viewing.  

For more information about exoplanets and NASA’s planet-finding program visit: http://planetquest.jpl.nasa.gov .

For more information about Spitzer, visit: http://www.nasa.gov/spitzer

For more information about the Kepler mission, visit: http://www.nasa.gov/kepler and http://kepler.nasa.gov.

Fro more information about European, Canadian and U.S. Planck visit: http://www.nasa.gov/planck

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