This image from NASA's Wide-field Infrared Survey Explorer (WISE) features comet 65/P Gunn. Comets are balls of dust and ice left over from the formation of the Solar System. As a comet approaches the Sun, it is heated and releases gas and dust from its surface, which is blown back by the solar wind into a long, spectacular tail. Comet 65/P Gunn's tail is seen here in red trailing off to the right of the comet's nucleus (near the center of the image).
Comet 65/P Gunn was discovered by James Gunn, a professor at Princeton University, N.J., in 1970. Gunn is the project scientist for the Sloan Digital Sky Survey, another important survey of the sky done in visible light. WISE observed the comet on April 24, 2010 in the contellation Capricornus (just one month after the comet's closest approach to the Sun). This is a single-frame observation, covering an area of 1.5 by 1.5 full moons (0.76 by 0.76 degrees).