Beyond the orbit of the asteroids the nature of planetary objects changes drastically. Jupiter, the largest of the planets, is covered by clouds made up of ammonia ice crystals. Beneath the clouds the atmosphere continues for many thousands of kilometers; any solid surface below this tremendous atmosphere is unreachable by our present technology. Voyager 1 took this photograph of Jupiter in January 1979 when the spacecraft was still 36 million kilometers (22 million miles) from the planet, but this view is much better than any photograph taken from Earth. The clouds are divided into belts around the rotational axis of the planet. The large red spot is a storm in the jovian atmosphere (the Great Red Spot; see slide #22). The coloring in the clouds may be due to materials brought up by wind currents from deeper levels in the atmosphere. On December 7, 1995, the Galileo probe obtained the first direct measurements of the upper atmosphere of Jupiter, providing data to depths beneath the visible ammonia clouds.
Voyager I image (Press Release P-20960).