kepler-47 system

Orbiting in the Habitable Zone of Two Suns

This diagram compares our own solar system to Kepler-47, a double-star system containing two planets, one orbiting in the so-called "habitable zone." This is the sweet spot in a planetary system where liquid water might exist on the surface of a planet.

Unlike our own solar system, Kepler-47 is home to two stars. One star is similar to the sun in size, but only 84 percent as bright. The second star is diminutive, measuring only one-third the size of the sun and less than one percent as bright. As the stars are smaller than our sun, the systems habitable zone is closer in.

The habitable zone of the system is ring-shaped, centered on the larger star. As the primary star orbits the center of mass of the two stars every 7.5 days, the ring of the habitable zone moves around.

This artist's rendering shows the planet comfortably orbiting within the habitable zone, similar to where Earth circles the sun. One year, or orbit, on Kepler-47c is 303 days. While not a world hospitable for life, Kepler-47c is thought to be a gaseous giant, slightly larger than Neptune, where an atmosphere of thick bright water-vapor clouds might exist.

The discovery demonstrates the diversity of planetary systems in our galaxy and provides more opportunities to search for life as we know it.

2012: Shadow of the Dark Rift

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Thick dust clouds block our night-time view of the Milky Way, creating what is sometimes called the Dark Rift. The fact that -- from the viewpoint of Earth -- the sun aligns with these clouds, or the galactic center, near the winter solstice is no cause for concern. Credit: A. Fujii 

One of the most bizarre theories about 2012 has built up with very little attention to facts. This idea holds that a cosmic alignment of the sun, Earth, the center of our galaxy -- or perhaps the galaxy's thick dust clouds -- on the winter solstice could for some unknown reason lead to destruction. Such alignments can occur but these are a regular occurrence and can cause no harm (and, indeed, will not even be at its closest alignment during the 2012 solstice.)

The details are as follows: Viewed far from city lights, a glowing path called the Milky Way can be seen arching across the starry sky. This path is formed from the light of millions of stars we cannot see individually. It coincides with the mid plane of our galaxy, which is why our galaxy is also named the Milky Way.

Thick dust clouds also populate the galaxy. And while infrared telescopes can see them clearly, our eyes detect these dark clouds only as irregular patches where they dim or block the Milky Way's faint glow. The most prominent dark lane stretches from the constellations Cygnus to Sagittarius and is often called the Great Rift, sometimes the Dark Rift.

Another impressive feature of our galaxy lies unseen in Sagittarius: the galactic center, about 28,000 light-years away, which hosts a black hole weighing some four million times the sun's mass.

The claim for 2012 links these two pieces of astronomical fact with a third -- the position of the sun near the galactic center on Dec. 21, the winter solstice for the Northern Hemisphere -- to produce something that makes no astronomical sense at all.

As Earth makes its way around the sun, the sun appears to move against the background stars, which is why the visible constellations slowly change with the seasons. On Dec. 21, 2012, the sun will pass about 6.6 degrees north of the galactic center -- that's a distance that looks to the eye to be about 13 times the full moon's apparent size -- and it's actually closer a couple of days earlier. There are different claims about why this bodes us ill, but they boil down to the coincidence of the solstice with the sun entering the Dark Rift somehow portending disaster or the mistaken notion that the sun and Earth becoming aligned with the black hole in the galactic center allows some kind of massive gravitational pull on Earth.

The first strike against this theory is that the solstice itself does not correlate to any movements of the stars or anything in the universe beyond Earth. It just happens to be the day that Earth's North Pole is tipped farthest from the sun.

Second, Earth is not within range of strong gravitational effects from the black hole at the center of the galaxy since gravitational effects decrease as the square of the distance from it. Earth is 93 million miles from the sun and 165 quadrillion miles from the Milky Way's black hole. The sun and the moon (a smaller mass, but much closer) are by far the most dominant gravitational forces on Earth. Throughout the course of the year, our distance from the Milky Way's black hole changes by about one part in 900 million – not nearly enough to cause a real change in gravity's pull. Moreover, we're actually nearest to the galactic center in the summer, not at the winter solstice.

Third, the sun appears to enter the part of the sky occupied by the Dark Rift every year at the same time, and its arrival there in Dec. 2012 portends precisely nothing.

Enjoy the solstice, by all means, and don't let the Dark Rift, alignments, solar flares, magnetic field reversals, potential impacts or alleged Maya end-of-the-world predictions get in the way.

Mars Rock Touched by NASA Curiosity has Surprises

This image shows where NASA's Curiosity rover aimed two different instruments to study a rock known as "Jake Matijevic."Image credit: NASA/JPL-Caltech/MSSS
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This image shows the wall of a scuffmark NASA's Curiosity made in a windblown ripple of Martian sand with its wheel. Image credit: NASA/JPL-Caltech/MSSS
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PASADENA, Calif. -- The first Martian rock NASA's Curiosity rover has reached out to touch presents a more varied composition than expected from previous missions. The rock also resembles some unusual rocks from Earth's interior.

The rover team used two instruments on Curiosity to study the chemical makeup of the football-size rock called "Jake Matijevic" (matt-EE-oh-vick) The results support some surprising recent measurements and provide an example of why identifying rocks' composition is such a major emphasis of the mission. Rock compositions tell stories about unseen environments and planetary processes.

"This rock is a close match in chemical composition to an unusual but well-known type of igneous rock found in many volcanic provinces on Earth," said Edward Stolper of the California Institute of Technology in Pasadena, who is a Curiosity co-investigator. "With only one Martian rock of this type, it is difficult to know whether the same processes were involved, but it is a reasonable place to start thinking about its origin."

On Earth, rocks with composition like the Jake rock typically come from processes in the planet's mantle beneath the crust, from crystallization of relatively water-rich magma at elevated pressure.

Jake was the first rock analyzed by the rover's arm-mounted Alpha Particle X-Ray Spectrometer (APXS) instrument and about the thirtieth rock examined by the Chemistry and Camera (ChemCam) instrument. Two penny-size spots on Jake were analyzed Sept. 22 by the rover's improved and faster version of earlier APXS devices on all previous Mars rovers, which have examined hundreds of rocks. That information has provided scientists a library of comparisons for what Curiosity sees.

"Jake is kind of an odd Martian rock," said APXS Principal Investigator Ralf Gellert of the University of Guelph in Ontario, Canada. "It's high in elements consistent with the mineral feldspar, and low in magnesium and iron."

ChemCam found unique compositions at each of 14 target points on the rock, hitting different mineral grains within it.

"ChemCam had been seeing compositions suggestive of feldspar since August, and we're getting closer to confirming that now with APXS data, although there are additional tests to be done," said ChemCam Principal Investigator Roger Wiens (WEENS) of Los Alamos National Laboratory in New Mexico.

Examination of Jake included the first comparison on Mars between APXS results and results from checking the same rock with ChemCam, which shoots laser pulses from the top of the rover's mast.

The wealth of information from the two instruments checking chemical elements in the same rock is just a preview. Curiosity also carries analytical laboratories inside the rover to provide other composition information about powder samples from rocks and soil. The mission is progressing toward getting the first soil sample into those analytical instruments during a "sol," or Martian day.

"Yestersol, we used Curiosity's first perfectly scooped sample for cleaning the interior surfaces of our 150-micron sample-processing chambers. It's our version of a Martian carwash," said Chris Roumeliotis (room-eel-ee-OH-tiss), lead turret rover planner at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

Before proceeding, the team carefully studied the material for scooping at a sandy patch called "Rocknest," where Curiosity is spending about three weeks.

"That first sample was perfect, just the right particle-size distribution," said JPL's Luther Beegle, Curiosity sampling-system scientist. "We had a lot of steps to be sure it was safe to go through with the scooping and cleaning."

Following the work at Rocknest, the rover team plans to drive Curiosity about 100 yards eastward and select a rock in that area as the first target for using the drill.

Hubble Goes to the eXtreme to Assemble Farthest-Ever View of the Universe

like photographers assembling a portfolio of best shots, astronomers have assembled a new, improved portrait of mankind's deepest-ever view of the universe.

(Credit: NASA; ESA; G. Illingworth, D. Magee, and P. Oesch, University of California, Santa Cruz; R. Bouwens, Leiden University; and the HUDF09 Team)
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Called the eXtreme Deep Field, or XDF, the photo was assembled by combining 10 years of NASA Hubble Space Telescope photographs taken of a patch of sky at the center of the original Hubble Ultra Deep Field. The XDF is a small fraction of the angular diameter of the full moon.

The Hubble Ultra Deep Field is an image of a small area of space in the constellation Fornax, created using Hubble Space Telescope data from 2003 and 2004. By collecting faint light over many hours of observation, it revealed thousands of galaxies, both nearby and very distant, making it the deepest image of the universe ever taken at that time.

The new full-color XDF image is even more sensitive, and contains about 5,500 galaxies even within its smaller field of view. The faintest galaxies are one ten-billionth the brightness of what the human eye can see.

This video zooms into the small areas of sky that the Hubble Space Telescope was aimed at to construct the eXtreme Deep Field, or XDF. The region is located in the southern sky, far away from the glare of the Milky Way, the bright plane of our galaxy. In terms of angular size, the field is a fraction the angular diameter of the full moon, yet it contains thousands of galaxies stretching back across time. (Credit: NASA; ESA; and G. Bacon and Z. Levay, STScI) › Download video (13 MB mp4)

Magnificent spiral galaxies similar in shape to our Milky Way and the neighboring Andromeda galaxy appear in this image, as do the large, fuzzy red galaxies where the formation of new stars has ceased. These red galaxies are the remnants of dramatic collisions between galaxies and are in their declining years. Peppered across the field are tiny, faint, more distant galaxies that were like the seedlings from which today's magnificent galaxies grew. The history of galaxies -- from soon after the first galaxies were born to the great galaxies of today, like our Milky Way -- is laid out in this one remarkable image.

Hubble pointed at a tiny patch of southern sky in repeat visits (made over the past decade) for a total of 50 days, with a total exposure time of 2 million seconds. More than 2,000 images of the same field were taken with Hubble's two premier cameras: the Advanced Camera for Surveys and the Wide Field Camera 3, which extends Hubble's vision into near-infrared light.

This illustration compares the angular size of the XDF field to the angular size of the full moon. A finger held at arm's length would appear to be about twice the width of the moon in this image. Note that this illustration does not show the actual observation of the XDF relative to the location of the moon. (Illustration Credit: NASA; ESA; and Z. Levay, STScI; Moon Image Credit: T. Rector; I. Dell'Antonio/NOAO/AURA/NSF)
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"The XDF is the deepest image of the sky ever obtained and reveals the faintest and most distant galaxies ever seen. XDF allows us to explore further back in time than ever before", said Garth Illingworth of the University of California at Santa Cruz, principal investigator of the Hubble Ultra Deep Field 2009 (HUDF09) program.

This image from 2009 shows an updated version of the Hubble Ultra Deep Field. The new eXtreme Deep Field could be considered a more detailed view of a portion of this image. (Credit: NASA; ESA; G. Illingworth, UCO/Lick Observatory and the University of California, Santa Cruz; R. Bouwens, UCO/Lick Observatory and Leiden University; and the HUDF09 Team)
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The universe is 13.7 billion years old, and the XDF reveals galaxies that span back 13.2 billion years in time. Most of the galaxies in the XDF are seen when they were young, small, and growing, often violently as they collided and merged together. The early universe was a time of dramatic birth for galaxies containing brilliant blue stars extraordinarily brighter than our sun. The light from those past events is just arriving at Earth now, and so the XDF is a "time tunnel into the distant past." The youngest galaxy found in the XDF existed just 450 million years after the universe's birth in the big bang.

Before Hubble was launched in 1990, astronomers could barely see normal galaxies to 7 billion light-years away, about halfway across the universe. Observations with telescopes on the ground were not able to establish how galaxies formed and evolved in the early universe.

Hubble gave astronomers their first view of the actual forms and shapes of galaxies when they were young. This provided compelling, direct visual evidence that the universe is truly changing as it ages. Like watching individual frames of a motion picture, the Hubble deep surveys reveal the emergence of structure in the infant universe and the subsequent dynamic stages of galaxy evolution.

The infrared vision of NASA's planned James Webb Space Telescope will be aimed at the XDF. The Webb telescope will find even fainter galaxies that existed when the universe was just a few hundred million years old. Because of the expansion of the universe, light from the distant past is stretched into longer, infrared wavelengths. The Webb telescope's infrared vision is ideally suited to push the XDF even deeper, into a time when the first stars and galaxies formed and filled the early "dark ages" of the universe with light.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Md., conducts Hubble science operations. STScI is operated by the Association of Universities for Research in Astronomy, Inc., in Washington.