Stellary Starry Universe

This false-color mosaic from NASA’s Cassini spacecraft shows the tail of Saturn’s huge northern storm. In mid-September 2004, the Cassini spacecraft chronicled a similar, but smaller, storm in the southern hemisphere called the “Dragon Storm.” The head of this storm is beyond the horizon in this view. Saturn’s atmosphere and its rings are shown here in a false color composite made from 12 images taken in near-infrared light through filters that are sensitive to varying degrees of methane absorption. Red and orange colors in this view indicate clouds that are deep in the atmosphere. Yellow and green colors, most noticeable near the top of the view, indicate intermediate clouds. White and blue indicate high clouds and haze. The rings appear as a thin horizontal line of bright blue because they are outside of the atmosphere and not affected by methane absorption. The oval in the upper left of this image that appears slightly blue is the same hole in the deep clouds of the planet’s atmosphere that can be seen near the tail in a larger false-color mosaic, PIA14903. The blue color comes from the high haze overlying the hole. This view looks toward the northern, sunlit side of the rings from just above the ring plane. The shadow of the moon Enceladus is visible on the planet in the lower left of the image. The images were taken with the Cassini spacecraft wide-angle camera using a combination of spectral filters sensitive to wavelengths of near-infrared light. The images filtered at 890 nanometers are projected as blue. The images filtered at 728 nanometers are projected as green, and images filtered at 752 nanometers are projected as red. The images were taken on Jan. 12, 2011, over about one hour at a distance of approximately 684,000 miles (1.1 million kilometers) from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 52 degrees. The images were re-projected to the same viewing geometry, so that scale in this final mosaic is 76 miles (122 kilometers) per pixel. Image Credit:NASA/JPL-Caltech/Space Science Institute

This artist’s concept shows a glowing patch of ultraviolet light near Saturn’s north pole that occurs at the “footprint” of the magnetic connection between Saturn and its moon Enceladus. The footprint and magnetic field lines are not visible to the naked eye, but were detected by the ultraviolet imaging spectrograph and the fields and particles instruments on NASA’s Cassini spacecraft. The footprint, newly discovered by Cassini, marks the presence of an electrical circuit that connects Saturn with Enceladus and accelerates electrons and ions along the magnetic field lines. In this image, the footprint is in the white box marked on Saturn, with the magnetic field lines in white and purple. A larger white square above Enceladus shows a cross-section of the magnetic field line between the moon and the planet. This pattern of energetic protons was detected by Cassini’s magnetospheric imaging instrument (MIMI) on Aug. 11, 2008. The patch near Saturn’s north pole glows because of the same phenomenon that makes Saturn’s well-known north and south polar auroras glow: energetic electrons diving into the planet’s atmosphere. However, the “footprint” is not connected to the rings of auroras around Saturn’s poles (shown as an orange ring around the north pole in this image). The Cassini plasma spectrometer complemented the MIMI data, with detection of field-aligned electron beams in the area. A team of scientists analyzed the charged particle data and concluded that the electron beams had sufficient energy flux to generate a detectable level of auroral emission at Saturn. Target locations were provided to Cassini’s ultraviolet imaging spectrograph team. On Aug. 26, 2008, the spectrograph obtained images of an auroral footprint in Saturn’s northern hemisphere. The newly discovered auroral footprint measured about 1,200 kilometers (750 miles) in the longitude direction and less than 400 kilometers (250 miles) in latitude, covering an area comparable to that of California or Sweden. It was located at about 65 degrees north latitude. In the brightest image the footprint shone with an ultraviolet light intensity of about 1.6 kilorayleighs, far less than the Saturnian polar auroral rings. This is comparable to the faintest aurora visible at Earth without a telescope in the visible light spectrum. Scientists have not yet found a matching footprint at the southern end of the magnetic field line. The background star field and false color images of Saturn and Enceladus were obtained by Cassini’s imaging science subsystem. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif. manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The ultraviolet imaging spectrograph team is based at the University of Colorado, Boulder. The magnetospheric imaging team is based at the Johns Hopkins University Applied Physics Laboratory, Laurel, Md. The Cassini plasma spectrometer team is based at the Southwest Research Institute, San Antonio, Texas. For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini . Image credit: NASA/JPL/JHUAPL/University of Colorado/Central Arizona College/SSI

A quintet of Saturn’s moons come together in the Cassini spacecraft’s field of view for this portrait. Janus (179 kilometers, or 111 miles across) is on the far left. Pandora (81 kilometers, or 50 miles across) orbits between the A ring and the thin F ring near the middle of the image. Brightly reflective Enceladus (504 kilometers, or 313 miles across) appears above the center of the image. Saturn’s second largest moon, Rhea (1,528 kilometers, or 949 miles across), is bisected by the right edge of the image. The smaller moon Mimas (396 kilometers, or 246 miles across) can be seen beyond Rhea also on the right side of the image. This view looks toward the northern, sunlit side of the rings from just above the ringplane. Rhea is closest to Cassini here. The rings are beyond Rhea and Mimas. Enceladus is beyond the rings. The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on July 29, 2011. The view was acquired at a distance of approximately 1.1 million kilometers (684,000 miles) from Rhea and 1.8 million kilometers (1.1 million miles) from Enceladus. Image Credit: NASA/JPL-Caltech/Space Science Institute

Scientists analyzing data from NASA’s Cassini spacecraft now have the first-ever, up-close details of a Saturn storm that is eight times the surface area of Earth.

Rhea emerges … After being occulted by the larger moon Titan. Occultation is a celestial event in which a larger body covers up a distant object. Observations such as this one, in which one moon passes close to or in front of another, help scientists refine their understanding of the orbits of Saturn’s moons. Titan is about 621,000 miles (1 million kilometers) from Cassini in this image. Rhea is about 1.4 million miles (2.3 million kilometers) from Cassini. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Oct. 27, 2009. Image scale is 4 miles (6 kilometers) per pixel on Titan and 9 miles (14 kilometers) per pixel on Rhea. Image Credit: NASA/JPL/Space Science Institute