A total of seven spacecraft have visited Jupiter to date, and six of them returned global images. (Because of the problem with its high-gain antenna, the Galileo orbiter returned no global views.) These six images show how Jupiter's atmospheric features are generally constant but can differ in detail with time. For example, the Great Red Spot, which has existed for at least three hundred years, has been steadily shrinking and becoming more round (less oval) with time. The Voyagers and Cassini found turbulent regions to the northeast of the Great Red Spot, while the area was clear to the Pioneers and New Horizons. The dark belts and bright zones shift slightly up and down and change in relative brightness over time.