In Full View: Saturn's Streaming 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.
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.
Image credit: NASA/JPL-Caltech/SSI/Hampton
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Comet ISON Approaching the Sun: This movie from NASA’s STEREO spacecraft's Heliospheric Imager shows Comet ISON, Mercury, Comet Encke and Earth over a five-day period from Nov. 20 to Nov. 25, 2013. The sun sits right of the field of view of this camera. Comet ISON, which will round the sun on Nov. 28, is what's known as a sungrazing comet, due to its close approach.
A comet’s journey through the solar system is perilous and violent. A giant ejection of solar material from the sun could rip its tail off. Before it reaches Mars -- at some 230 million miles away from the sun -- the radiation of the sun begins to boil its water, the first step toward breaking apart. And, if it survives all this, the intense radiation and pressure as it flies near the surface of the sun could destroy it altogether.
Even if the comet does not survive, tracking its journey will help scientists understand what the comet is made of, how it reacts to its environment, and what this explains about the origins of the solar system. Closer to the sun, watching how the comet and its tail interact with the vast solar atmosphere can teach scientists more about the sun itself.
#Comet #ISON entered the field of view of the HI-1 camera on NASA's Solar Terrestrial Relations Observatory, or STEREO, on Nov. 21, 2013, and the comet shows up clearly, appearing to still be intact.
Dark "clouds" coming from the right are more dense areas in the solar wind, causing ripples in Comet Encke's tail. Using comet tails as tracers can provide valuable data about solar wind conditions near the sun.
Image Credit: Karl Battams/NASA/STEREO/CIOC
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Antarctic Ozone Hole Slightly Smaller than Average This Year: The ozone hole that forms each year in the stratosphere over Antarctica was slightly smaller in 2013 than average in recent decades, according to NASA satellite data. This video shows the latest false-color view of total ozone over the Antarctic pole. The purple and blue colors are where there is the least ozone, and the yellows and reds are where there is more ozone.
The ozone hole is a seasonal phenomenon that starts to form during the Antarctic spring (August and September). The September-October 2013 average size of the hole was 8.1 million square miles (21 million square kilometers). For comparison, the average size measured since the mid-1990s when the annual maximum size stopped growing is 8.7 million square miles (22.5 million square kilometers). However, the size of the hole in any particular year is not enough information for scientists to determine whether a healing of the hole has begun.
What's it like to fly along with the SOFIA mission? In this time-lapse, you see the Stratospheric Observatory for Infrared Astronomy (SOFIA) telescope during a scientific observation gathering mission. SOFIA is a heavily modified 747SP aircraft that carries a telescope with an effective diameter of 100 inches (2.5 meters) to altitudes above 39,000 feet (12 km), beyond the obscuring layer of water vapor in Earth's atmosphere.
In this video, it appears SOFIA moves — but in reality, the telescope stays extremely stable and steady during observations. The motion seen in this video is actually the airplane moving around the telescope, which is steady. The telescope is designed this way to account for turbulence so that it is stable for accurate observations.
SOFIA is a joint project of NASA and the German Aerospace Center (DLR) that is based at NASA's Dryden Aircraft Operations Facility in Palmdale, Calif. The SOFIA Science Center is located at NASA Ames Research Center in Mountain View, Cailf.
Video credit: Dr. Daniel Angerhausen, Rensselaer Polytechnic Institute
This summer's sea ice minimum in the Arctic is still the sixth lowest extent of the satellite record and is 432,000 square miles (1.12 million square kilometers) lower than the 1981-2010 average, roughly the size of Texas and California combined.
The ice cap covering the Arctic Ocean shrinks and expands with the passing of the seasons, melting in the summer and refreezing during the long, frigid Arctic winter. This year, cooler weather in the spring and summer led to a late start of the melt season and overall less melt.
This animation shows the daily Arctic sea ice extent and seasonal land cover change through Sept. 12, 2013, the day before NSIDC estimated that sea ice reached its minimum area of extent. The data was provided by the Japan Aerospace Exploration Agency from their AMSR2 instrument aboard the GCOM-W1 satellite.
This year, Arctic temperatures were 1.8 to 4.5 degrees Fahrenheit (1 to 2.5 degrees Celsius) lower than average, according to NASA's Modern Era Retrospective analysis for Research and Applications, a merging of observations and a modeled forecast. The colder temperatures were in part due to a series of summer cyclones. In August 2012, a big storm caused havoc on the Arctic Ocean’s icy cover, but this summer’s cyclones have had the opposite effect: under cloudier conditions, surface winds spread the ice over a larger area.
Image Credit: NASA Goddard's Scientific Visualization Studio/Cindy Starr
