Chandra Release - April 5, 2004

Visual Description: Titan

Two images are shown in this feature - one is an X-ray image of the Crab Nebula (right) and the other is an X-ray image of the shadow of the moon Titan (left inset). The Crab X-ray image appears bright blue and white in a bell shape on a black background, while the image of Titan is a small, black fuzzy dot on a textured or speckled blue background.  On January 5, 2003, Titan — Saturn's largest moon and the only moon in the solar system with a thick atmosphere — crossed in front of the Crab Nebula, a bright, extended X-ray source. Titan's transit enabled Chandra to image the one-arcsecond-diameter X-ray shadow cast by the moon (inset). This tiny shadow corresponds to the size of a dime as viewed from about two and a half miles.  The diameter of Titan's shadow was found to be larger than the known diameter of its solid surface. This difference in diameters yields a measurement of about 550 miles (880 kilometers) for the height of the X-ray absorbing region of Titan's atmosphere.