NASA's Cassini Spacecraft Obtains Best Views of Saturn Hexagon.

This colorful view from NASA's Cassini mission is the highest-resolution view of the unique six-sided jet stream at Saturn's north pole known as "the hexagon." This movie, made from images obtained by Cassini's imaging cameras, is the first to show the hexagon in color filters, and the first movie to show a complete view from the north pole down to about 70 degrees north latitude. Scientists can see the motion of a wide variety of cloud structures that reside within the hexagon in this movie. There is a massive hurricane tightly centered on the north pole, with an eye about 50 times larger than the average hurricane eye on Earth. (More information about that Saturn hurricane is at PIA14947.) Numerous small vortices are also present, which appear as reddish ovals. Some of these vortices spin clockwise while the hexagon and hurricane spin counterclockwise. Some of those smaller features are swept along with the jet stream of the hexagon, as if on a racetrack. The biggest of these vortices, seen near the lower right corner of the hexagon and appearing whitish, spans about 2,200 miles (3,500 kilometers), approximately twice the size of the largest hurricane on Earth. The differences in this version of the movie, in which different wavelengths of light from ultraviolet to visible to infrared have been assigned colors, show a distinct contrast between the types of atmospheric particles inside and outside the hexagon. Inside the hexagon there are fewer large haze particles and a concentration of small haze particles, while outside the hexagon, the opposite is true. The jet stream that makes up the hexagon seems to act like a barrier, which results in something like the "ozone hole" in the Antarctic. This movie shows a view from directly over the north pole, keeping up with the rotation of the planet so that all the motion seen on the screen is the motion of the hexagonal jet stream or the storms inside of it, without any added motion from the spinning of the planet itself. The original images were re-projected to show this polar view. High-resolution views of the hexagon have only recently become possible because of the changing of the seasons at Saturn and changes in the Cassini spacecraft's orbit. The north pole was dark when Cassini first arrived in July 2004. The sun really only began to illuminate the entire interior of the hexagon in August 2009, with the start of northern spring. In late 2012, Cassini began making swings over Saturn's poles, giving it better views of the hexagon. The eight frames of the movie were captured over 10 hours on December 10, 2012. Each of the eight frames consists of 16 map-projected images (four per color filter, and four filters per frame) so the movie combines data from 128 images total. In this color scheme, scientists assigned red to the 0.750-micron part of the light spectrum (near infrared). This part of the spectrum penetrates the high-altitude haze layer to sense the top of tropospheric cloud deck. They assigned green to the 0.727-micron part of the light spectrum that senses the upper tropospheric haze (a near-infrared wavelength corresponding to a methane absorption band). They assigned blue to the sum of blue and ultraviolet broadband filters -- combined, this blue channel covers between 0.400 and 0.500 microns (covering very near ultraviolet to blue in visible light). This part of the spectrum is sensitive to small aerosols. To human eyes, the hexagon and north pole would appear in tones of gold and blue. See PIA14945 for a still image of the area in natural color. Video credit: NASA/JPL-Caltech/SSI/Hampton University, Note: For more information, see PIA17653: Hexagon in Silhouette, PIA17654: Looking Down on the Hexagon in Infrared, and NASA's Cassini Spacecraft Obtains Best Views of Saturn Hexagon.Source: Article

Read More........→January 01, 2014

Light From The Darkness

Credit: ESO

On the left of this new image there is a dark column resembling a cloud of smoke. To the right shines a small group of brilliant stars. At first glance these two features could not be more different, but they are in fact closely linked. The cloud contains huge amounts of cool cosmic dust and is a nursery where new stars are being born. It is likely that the Sun formed in a similar star formation region more than four billion years ago. This cloud is known as Lupus 3 and it lies about 600 light-years from Earth in the constellation of Scorpius (The Scorpion). The section shown here is about five light-years across. As the denser parts of such clouds contract under the effects of gravity they heat up and start to shine. At first this radiation is blocked by the dusty clouds and can only be seen by telescopes observing at longer wavelengths than visible light, such as the infrared. But as the stars get hotter and brighter their intense radiation and stellar winds gradually clear the clouds around them until they emerge in all their glory. This zoom sequence starts with a view of the central parts of the Milky Way. We close in on a region in the constellation of Scorpius (The Scorpion). The final view, taken with the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile, shows a dark cloud where new stars are forming along with a cluster of brilliant stars that have already burst out of their dusty stellar nursery. This cloud is known as Lupus 3 and it lies about 600 light-years from Earth in the constellation of Scorpius (The Scorpion). It is likely that the Sun formed

Credit: ESO/F. Comeron, Nick Risinger (skysurvey.org), Digitized Sky Survey 2, Music: delmo "acoustic" 

in a similar star formation region more than four billion years ago.The bright stars right of the centre of this new picture form a perfect example of a small group of such hot young stars. Some of their brilliant blue light is being scattered off the remaining dust around them. The two brightest stars are bright enough to be seen easily with a small telescope or binoculars. They are young stars that have not yet started to shine by nuclear fusion in their cores and are still surrounded by glowing gas [1]. They are probably less than one million years old. Although they are less obvious at first glance than the bright blue stars, surveys have found many other very young stellar objects in this region, which is one of the closest such stellar nurseries to the Sun. This wide-field view shows a dark cloud where new stars are forming along with cluster of brilliant stars that have already burst out of their dusty stellar nursery. This cloud is known as Lupus 3 and it lies about 600 light-years from Earth in the constellation of Scorpius (The Scorpion). It is likely that the Sun formed in a similar star formation region more than four billion years ago. This view

Credit: ESO/Digitized Sky Survey 2, Acknowledgement: Davide De Martin

was created from images forming part of the Digitized Sky Survey 2. Star formation regions can be huge, such as the Tarantula Nebula (eso0650) where hundreds of massive stars are being formed. However, most of the stars in our and other galaxies are thought to have formed in much more modest regions like the one shown here, where only two bright stars are visible and no very heavy stars are formed. For this reason, the Lupus 3 region is both fascinating for astronomers and a beautiful illustration of the early stages of the life of stars. This video pan sequence gives a detailed view of a dark cloud where new stars are forming along with a cluster of brilliant stars that have already burst out of their dusty stellar nursery. This cloud is known as Lupus 3 and it lies about 600 light-years from Earth in the constellation of Scorpius (The Scorpion). It is likely that the Sun formed in a similar star formation region more than four billion years ago. This picture was taken with the MPG/ESO 2.2-metre telescope at the La Silla

Credit: ESO/F. Comeron

Observatory  in Chile and is the best visible light image ever taken of this little-known object. This chart shows the location of the dark cloud Lupus 3 in the constellation of Scorpius (The Scorpion). This map shows most of the stars visible to the unaided eye under good conditions, and the location of the cloud and newly formed hot young  stars is marked with a red circle. The brightest two stars in this object can easily be seen with a small telescope or binoculars and form an attractive double star. The dark cloud itself only shows up in longer exposure images. [1] These are known as Herbig Ae/Be stars after the 

Credit: ESO, IAU and Sky & Telescope

astronomer who first identified them. The A and B refer to the spectral types of the stars, somewhat hotter than the Sun, and the "e" indicates that emission lines are present in their spectra, due to the glow from the gas around them. They shine by converting gravitational potential energy into heat as they contract. Contacts and sources: Richard Hook, ESO,Source: Nano Patents And Innovations

Read More........→January 19, 2013