A solar eruption gracefully rose up from the Sun on December 31, 2012, twisting and turning. Magnetic forces drove the flow of plasma, but without sufficient force to overcome the Sun’s gravity much of the plasma fell back into the Sun.
The Earth is superimposed on this image to give readers a sense of the scale. The length of the eruption extends about 160,000 miles out from the Sun. With Earth about 7,900 miles in diameter, this relatively minor eruption is about 20 times the diameter of our planet.
Look up at the night sky and you'll see stars, sure. But the sky is also filled with planets - billions and billions of them at least.
That's the conclusion of a new study by astronomers at the California Institute of Technology in Pasadena, which provides yet more evidence that planetary systems are the cosmic norm. The team made their estimate while analyzing planets orbiting a star called Kepler-32 - planets that are representative, they say, of the vast majority of planets in our galaxy and thus serve as a perfect case study for understanding how most of these worlds form.
"There are at least 100 billion planets in the galaxy, just our galaxy," says John Johnson, assistant professor of planetary astronomy at Caltech and coauthor of the study, which was recently accepted for publication in the Astrophysical Journal. "That's mind-boggling."
"It's a staggering number, if you think about it," adds Jonathan Swift, a postdoctoral student at Caltech and lead author of the paper. "Basically, there's one of these planets per star."
The planetary system in question, which was detected by NASA's Kepler space telescope, contains five planets. Two of the planets orbiting Kepler-32 had previously been discovered by other astronomers. The Caltech team confirmed the remaining three, then analyzed the five-planet system and compared it to other systems found by Kepler.
The planets orbit a star that is an M dwarf - a type that accounts for about three-quarters of all stars in the Milky Way. M-dwarf systems like Kepler-32's are quite different from our own solar system. For one, M dwarfs are cooler and much smaller than the Sun. Kepler-32, for example, has half the mass of the Sun and half its radius. The radii of its five planets range from 0.8 to 2.7 times that of Earth, and those planets orbit extremely close to their star. The whole Kepler-32 system fits within just over a tenth of an astronomical unit (the average distance between Earth and the Sun) - a distance that is about a third of the radius of Mercury's orbit around the Sun.
The fact that M-dwarf systems vastly outnumber other kinds of systems carries a profound implication, according to Johnson, which is that our solar system is extremely rare. "It's just a weirdo," he says.
Appearing like a winged fairy-tale creature poised on a pedestal, this object is actually a billowing tower of cold gas and dust rising from a stellar nursery called the Eagle Nebula. The soaring tower is 9.5 light-years or about 57 trillion miles high, about twice the distance from our Sun to the next nearest star.
Stars in the Eagle Nebula are born in clouds of cold hydrogen gas that reside in chaotic neighborhoods, where energy from young stars sculpts fantasy-like landscapes in the gas. The tower may be a giant incubator for those newborn stars. A torrent of ultraviolet light from a band of massive, hot, young stars [off the top of the image] is eroding the pillar.
The starlight also is responsible for illuminating the tower's rough surface. Ghostly streamers of gas can be seen boiling off this surface, creating the haze around the structure and highlighting its three-dimensional shape. The column is silhouetted against the background glow of more distant gas.
The edge of the dark hydrogen cloud at the top of the tower is resisting erosion, in a manner similar to that of brush among a field of prairie grass that is being swept up by fire. The fire quickly burns the grass but slows down when it encounters the dense brush. In this celestial case, thick clouds of hydrogen gas and dust have survived longer than their surroundings in the face of a blast of ultraviolet light from the hot, young stars.
Inside the gaseous tower, stars may be forming. Some of those stars may have been created by dense gas collapsing under gravity. Other stars may be forming due to pressure from gas that has been heated by the neighboring hot stars.
The first wave of stars may have started forming before the massive star cluster began venting its scorching light. The star birth may have begun when denser regions of cold gas within the tower started collapsing under their own weight to make stars.
The bumps and fingers of material in the center of the tower are examples of these stellar birthing areas. These regions may look small but they are roughly the size of our solar system. The fledgling stars continued to grow as they fed off the surrounding gas cloud. They abruptly stopped growing when light from the star cluster uncovered their gaseous cradles, separating them from their gas supply.
Ironically, the young cluster's intense starlight may be inducing star formation in some regions of the tower. Examples can be seen in the large, glowing clumps and finger-shaped protrusions at the top of the structure. The stars may be heating the gas at the top of the tower and creating a shock front, as seen by the bright rim of material tracing the edge of the nebula at top, left. As the heated gas expands, it acts like a battering ram, pushing against the darker cold gas. The intense pressure compresses the gas, making it easier for stars to form. This scenario may continue as the shock front moves slowly down the tower.
The dominant colors in the image were produced by gas energized by the star cluster's powerful ultraviolet light. The blue color at the top is from glowing oxygen. The red color in the lower region is from glowing hydrogen. The Eagle Nebula image was taken in November 2004 with the Advanced Camera for Surveys aboard NASA's Hubble Space Telescope.
Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)
Explanation from: http://hubblesite.org/newscenter/archive/releases/2005/12/image/b/
How much of planet Earth is made of water? Very little, actually. Although oceans of water cover about 70 percent of Earth's surface, these oceans are shallow compared to the Earth's radius. This illustration shows what would happen if all of the water on or near the surface of the Earth were bunched up into a ball. The radius of this ball would be only about 700 kilometers, less than half the radius of the Earth's Moon, but slightly larger than Saturn's moon Rhea which, like many moons in our outer Solar System, is mostly water ice. How even this much water came to be on the Earth and whether any significant amount is trapped far beneath Earth's surface remain topics of research.
Illustration Credit & Copyright: Jack Cook, WHOI, Howard Perlman, USGS
Explanation from: http://apod.nasa.gov/apod/ap120515.html
This is a mosaic image, one of the largest ever taken by NASA's Hubble Space Telescope of the Crab Nebula, a six-light-year-wide expanding remnant of a star's supernova explosion. Japanese and Chinese astronomers recorded this violent event nearly 1,000 years ago in 1054, as did, almost certainly, Native Americans.The orange filaments are the tattered remains of the star and consist mostly of hydrogen. The rapidly spinning neutron star embedded in the center of the nebula is the dynamo powering the nebula's eerie interior bluish glow. The blue light comes from electrons whirling at nearly the speed of light around magnetic field lines from the neutron star. The neutron star, like a lighthouse, ejects twin beams of radiation that appear to pulse 30 times a second due to the neutron star's rotation. A neutron star is the crushed ultra-dense core of the exploded star.
The Crab Nebula derived its name from its appearance in a drawing made by Irish astronomer Lord Rosse in 1844, using a 36-inch telescope. When viewed by Hubble, as well as by large ground-based telescopes such as the European Southern Observatory's Very Large Telescope, the Crab Nebula takes on a more detailed appearance that yields clues into the spectacular demise of a star, 6,500 light-years away.
The newly composed image was assembled from 24 individual Wide Field and Planetary Camera 2 exposures taken in October 1999, January 2000, and December 2000. The colors in the image indicate the different elements that were expelled during the explosion. Blue in the filaments in the outer part of the nebula represents neutral oxygen, green is singly-ionized sulfur, and red indicates doubly-ionized oxygen.
Image Credit: NASA, ESA, J. Hester and A. Loll
Explanation from: http://hubblesite.org/newscenter/archive/releases/2005/37/image/a/
Storms on the distant horizon and comet dust raining through the heavens above are combined in this alluring nightscape. The scene was recorded in the early hours of August 13, 2010 from the Keota Star Party site on the Pawnee National Grasslands of northeastern Colorado, USA. Looking east across the prairie, the composite of 8 consecutive exposures each 30 seconds long captures the flash of lightning and a bright Perseid meteor. On the right, even the clouds can't block the light from brilliant planet Jupiter, whose mythological namesake knew how to handle both lightning bolts and meteors. Of course, this meteor's streak points back toward the shower's radiant in the heroic constellation Perseus, sharing a starry background that includes the Pleiades star cluster poised above the storm clouds. Just above the bright meteor lies the faint Andromeda Galaxy.
Image Credit & Copyright: Robert Arn
Explanation from: http://apod.nasa.gov/apod/ap100821.html
Who guards the north? Judging from this photograph, possibly giant trees covered in snow and ice. The picture was taken in 2011 in Finnish Lapland where weather can include sub-freezing temperatures and driving snow. Surreal landscapes sometimes result, where common trees become cloaked in white and so appear, to some, as watchful aliens. Far in the distance, behind this uncommon Earthly vista, is a more common sight - a Belt of Venus that divided a darkened from sunlit sky as the Sun rose behind the photographer. Of course, in the spring, the trees have thawed and Lapland looks much different.
Why is this aurora strikingly pink? When photographing picturesque Crater Lake in Oregon, USA in June 2012, the background sky lit up with auroras of unusual colors. Although much is known about the physical mechanisms that create auroras, accurately predicting the occurrence and colors of auroras remains a topic of investigation. Typically, it is known, the lowest auroras appear green. These occur at about 100 kilometers high and involve atmospheric oxygen atoms excited by fast moving plasma from space. The next highest auroras -- at about 200 kilometers up -- appear red, and are also emitted by resettling atmospheric oxygen. Some of the highest auroras visible -- as high as 500 kilometers up -- appear blue, and are caused by sunlight-scattering nitrogen ions. When looking from the ground through different layers of distant auroras, their colors can combine to produce unique and spectacular hues, in this case rare pink hues seen above. As Solar Maximum nears in 2013, particle explosions from the Sun are sure to continue and likely to create even more memorable nighttime displays.