29 September 2010
Credit: NASA/JPL/University of Arizona/University of Leicester
The auroras are among the most spectacular natural phenomena. They occur usually in Earth’s polar regions, when energetic particles, streaming from the Sun, hit Earth’s upper atmosphere, exciting atoms of nitrogen and oxygen. These atoms are thus induced to emit fascinating lights, in various colors, including green and red. NASA’s Cassini spacecraft was able to observe auroras of Saturn, the ringed giant planet.
NASA recently published an interesting infrared image of Saturn, showing the glow of the planet’s auroras. The image was constructed from data acquired by the Saturn-orbiting Cassini spacecraft. The colors are false, and represent the different emissions of Saturn. The aurora emission, visible over Saturn’s south polar region, is shown in green.
Blue indicates reflected sunlight. Red is due to thermal emission from Saturn’s interior. Saturn's rings reflect sunlight, therefore they are blue.
The dark spots and banded features in the image are clouds and small storms that are part of the deeper weather systems and circulation patterns of Saturn. They are illuminated from below, by Saturn's thermal emission, and thus appear in silhouette.
The composite image was made from 65 individual observations, applying Cassini's visual and infrared mapping spectrometer, on 1 November 2008.
References
NASA
www.nasa.gov/
Wikipedia
Aymen Mohamed Ibrahem
Senior Astronomy Specialist