In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms (which themselves are generally referred to in non-technical language as “constellations”), which are patterns formed by prominent stars within apparent proximity to one another on Earth’s night sky.
There are also numerous historical constellations not recognized by the IAU or constellations recognized in regional traditions of astronomy or astrology, such as Chinese, Hindu and Australian Aboriginal.
This video of the sun based on data from NASA’s Solar Dynamics Observatory, or SDO, shows the wide range of wavelengths — invisible to the naked eye — that the telescope can view. SDO converts the wavelengths into an image humans can see, and the light is colorized into a rainbow of colors.
As the colors sweep around the sun in the movie, viewers should note how different the same area of the sun appears. This happens because each wavelength of light represents solar material at specific temperatures. Different wavelengths convey information about different components of the sun’s surface and atmosphere, so scientists use them to paint a full picture of our constantly changing and varying star.
Yellow light of 5800 Angstroms, for example, generally emanates from material of about 10,000 degrees F (5700 degrees C), which represents the surface of the sun. Extreme ultraviolet light of 94 Angstroms, which is typically colorized in green in SDO images, comes from atoms that are about 11 million degrees F (6,300,000 degrees C) and is a good wavelength for looking at solar flares, which can reach such high temperatures. By examining pictures of the sun in a variety of wavelengths — as is done not only by SDO, but also by NASA’s Interface Region Imaging Spectrograph, NASA’s Solar Terrestrial Relations Observatory and the European Space Agency/NASA Solar and Heliospheric Observatory — scientists can track how particles and heat move through the sun’s atmosphere.
The 2.9 minute movie was created by NASA’s Scientific Visualization Studio or SVS at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and is available at the SVS website: http://svs.gsfc.nasa.gov/goto?11385