When the HST captured this image of Jupiter on May 18, 1994, its moon Io was
crossing over the disk of the planet. The very dark circular spot on Jupiter is the shadow of Io. Had you been located on Jupiter's cloud tops inside the shadow, you would have experienced a total eclipse of the Sun. Io itself is the yellow-orange disk just to the upper right of the shadow.
Ten times the size of Earth, Jupiter is the largest planet in the solar system. It is made up almost entirely of hydrogen and helium. Clouds of water vapor, methane and ammonia float in the turbulent outer layers, creating the ever-changing pattern of swirling bands and spots. Jupiter's most famous cloud feature, the Great Red Spot, is just rotating into view on the left side of the disk.
This was the best image of Jupiter obtained since the spacecraft Voyager 2 flew by the planet in 1979. The HST resolves details as small as 200 kilometers (124 miles) across even though Jupiter was 670 million kilometers (420 million miles) away.
Camera: WFPC2 in PC mode.
Technical Information: Exposures through three color filters (red, green and blue) combined to create a true color image. Jupiter's rotation between the exposures creates a blue and red fringe on either side of the disk.
Credit: H. A. Weaver and T. E. Smith (STScI), J. T. Trauger and R. W. Evans (JPL), and NASA
