Like Uranus, Neptune's color is due to the presence of methane in its atmosphere. Neptune has only 1% more methane than Uranus, but this is enough to make it a much deeper blue color. Atmospheric circulation is visible on Neptune; in fact, it even has a Great Dark Spot , like the Great Red Spot on Jupiter. This Spot is due to rising currents of gas. (However, the Hubble Space Telescope didn't see the Great Dark Spot when it last looked at Neptune; it could be that the storm is over!) The cloud patterns on Neptune are driven by heat flowing from the interior and the planet's rapid rotation. |