Earthlike Planet Found Orbiting at Right Distance for Life

Kepler-22b is first planet confirmed "smack in the middle of the habitable zone."

A possible Earth twin has been confirmed orbiting a sunlike star 600 light-years away—and the new planet may be in just the right spot for supporting life, NASA announced Monday.
Discovered by the Kepler space mission, the new planet—dubbed Kepler-22b—is the first world smaller than Neptune to be found in middle of its star's habitable zone.


Also called the Goldilocks zone, the habitable zone is the region around a star where a planet's surface is not too hot and not too cold for liquid water—and thus life as we know it—to exist.
(Also see "New Planet May Be Among Most Earthlike—Weather Permitting.")
Other planets have been spotted in the habitable zones of their stars, but most of those worlds are Jupiter- or Neptune-size bodies that are unlikely to harbor life.

"The number of confirmed sub-Neptunian worlds in their habitable zones are few and far between, because they are the hardest ones to find," said Natalie Batalha, Kepler's deputy science team leader at San Jose State University in California.

(Related: "Six New Planets—Mini-Neptunes Found Around Sunlike Star.")
In fact, only two known planets fit this description so far—Gliese 581d and HD 85512—and both worlds orbit at the very edges of their stars' habitable zones, making them more akin to Venus and Mars than to Earth.

"What makes this particular discovery so exciting is that this planet is right smack in the middle of the habitable zone," Batalha said.
"It's also orbiting a star that's almost a twin of our sun, whereas the other two detections are orbiting significantly cooler stars."
(Find out more about the possibly habitable worlds in the Gliese system.)

Getting Closer to Truly Earthlike
The Kepler mission finds new worlds by simultaneously monitoring 150,000 stars for dips in brightness, which are indicative of planets passing in front of—or transiting—their stars.

Kepler-22b was among the 54 roughly Earth-size planet candidates announced by the Kepler team in February. But the spacecraft needs to watch at least three transits to confirm that a signal is a planet.
"Fortune smiled upon us with the detection of this planet," William Borucki, Kepler's principal investigator at the NASA Ames Research Center in Moffett Field, California, said in a statement.
"The first transit was captured just three days after we declared the spacecraft operationally ready. We witnessed the defining third transit over the 2010 holiday season."

The new planet is about 2.4 times the radius of Earth, but scientists don't yet know its composition, because they are still missing a crucial piece of information: Kepler-22b's mass.
(See "NASA Finds Smallest Earthlike Planet Outside Solar System.")
The Kepler team is hopeful, however, that the mass of Kepler-22b could be calculated with the help of a new ground-based instrument in the Spanish Canary Islands that will begin observations next spring.
Called HARPS North, the new telescope is capable of measuring with high precision a planet's doppler velocity—changes in the frequency of light from an object in space as it moves toward or away from Earth.
With this information, scientists can calculate the mass, and therefore the density, of Kepler-22b and determine whether it's a rocky planet or a water world.

"We are really hopeful that HARPS North might be able to be a really big help in this quest for the mass of this planet," San Jose State's Batalha said.
"We're just getting closer and closer to what is truly Earthlike, and that progress is exciting to watch."
The new planet Kepler-22b will be detailed in an upcoming issue of the Astrophysical Journal.

source news nationalgeographic

A New Milestone for New Horizons

 

Artist’s rendering of New Horizons. Southwest Research Institute (Dan Durda)/Johns Hopkins University Applied Physics Laboratory (Ken Moscati)

Last Friday, December 2, 2011, NASA’s New Horizons spacecraft became the closest spacecraft ever to Pluto, a record previously held by Voyager 1 which came within 983 million miles of Pluto on January 29, 1986. This marks the beginning of a new period in the New Horizons mission, when every day – every moment, in fact – is the closest a manmade vehicle has ever come to the distant dwarf planet!

“What a cool milestone!” said Alan Stern of the Southwest Research Institute and New Horizons Principal Investigator. “Although we’re still a long way – 1.5 billion kilometers from Pluto – we’re now in new territory as the closest any spacecraft has ever gotten to Pluto, and getting closer every day by over a million kilometers.”

Launched on January 19, 2006, New Horizons has been traveling at incredible speeds through the solar system for 2,149 days (as of the time of this writing.) The spacecraft is one of the fastest machines ever created, speeding through interplanetary space at up to 47,000 mph. That’s over twenty times the speed of a rifle bullet – almost 13 miles a second!

Watch a video of New Horizons’ launch from Cape Canaveral.

Yet, even at that rate, it will take New Horizons another 3 1/2 years to finally reach Pluto, a frozen and enigmatic world holding court with its four (known) moons at the far reaches of the solar system. At its closest Pluto is still over 4.2 billion miles from Earth. From that distance the Sun is just an extra-bright star in an eternally twilit sky, casting about as much heat as the pad of sticky-notes on your desk.

 

Still, over the course of its 248-year-long orbit that heat is enough to visibly change the coloration of its surface, at least as most recently seen by the Hubble Space Telescope in a series of images acquired from 2002-2003. Likely an effect of surface materials sublimating and re-freezing across Pluto’s surface, these shifting patterns indicate that Pluto is a dynamic place that undoubtedly has many more surprises in store for NASA’s steadily approaching spacecraft.

The most detailed view to date of the entire surface of Pluto, constructed from multiple NASA Hubble Space Telescope photographs taken from 2002 to 2003. The center disk has a mysterious bright spot that is unusually rich in carbon monoxide frost. Credit: NASA, ESA, and M. Buie (Southwest Research Institute).

The most detailed view to date of the entire surface of Pluto, constructed from multiple NASA Hubble Space Telescope photographs taken from 2002 to 2003. The center disk has a mysterious bright spot that is unusually rich in carbon monoxide frost. Credit: NASA, ESA, and M. Buie (Southwest Research Institute).

New Horizons will ultimately make a close pass by Pluto on July 14, 2015, imaging the dwarf planet with a suite of science instruments, in particular its high-resolution LORRI (Long Range Reconnaissance Imager) camera which will be able to resolve features on its surface as small as 200 feet across.

After its close encounter with our solar system’s erstwhile ninth planet New Horizons will continue outwards into the Kuiper Belt, an even further region where icy bodies and even more worlds like Pluto reside, orbiting the Sun in ever larger and longer orbits.

New Horizons may even visit one of these distant worlds, should the mission be extended.

Ultimately, in another few years (1,312 days and counting, to be exact) we will learn more about Pluto in one sudden and glorious burst of information than we ever have in the 81 years since its discovery, thanks to New Horizons. Until then we can only imagine what it might find.

See you in 2015!