Atmosphere of Triton asymmetry was actually observed during star occultations by Triton in 1990s. Before Voyager 2 arrived, a nitrogen and methane atmosphere with a density as much as 30% that of Earth had been suggested. This proved to be a great overestimate, similar to the predictions of the atmospheric density of Mars, but like on Mars, a denser early atmosphere is postulated. Voyager 2 flew past Triton five hours after closest approach to Neptune in mid-late August 1989. During the flyby, Voyager 2 took measurements of the atmosphere, finding methane and nitrogen in the atmosphere. In the 1990s, observations from Earth were
Atmosphere of Jupiter is commonly treated as the base of the troposphere. In scientific literature, the 1 bar pressure level is usually chosen as a zero point for altitudes—a "surface" of Jupiter. As with Earth, the top atmospheric layer, the exosphere, does not have a well defined upper boundary. The density gradually decreases until it smoothly transitions into the interplanetary medium approximately 5,000 km above the "surface". The vertical temperature gradients in the Jovian atmosphere are similar to those of the atmosphere of Earth. The temperature of the troposphere decreases with height until it reaches a minimum at the tropopause, which is the