Atmosphere of Venus
In 1761, Russian polymath Mikhail Lomonosov observed an arc of light surrounding the part of Venus off the Sun's disc at the beginning of the egress phase of the transit and concluded that Venus has an atmosphere. In 1940, Rupert Wildt calculated that the amount of CO in the Venusian atmosphere would raise surface temperature above the boiling point for water. This was confirmed when Mariner 2 made radiometer measurements of the temperature in 1962. In 1967, Venera 4 confirmed that the atmosphere consisted primarily of carbon dioxide.
Extraterrestrial atmosphere
The atmosphere of Neptune is similar to that of Uranus. It is about 80% hydrogen, 19% helium, and 1.5% methane. However the weather activity on Neptune is much more active, and its atmosphere is much bluer than that of Uranus. The upper levels of the atmosphere reach temperatures of about 55 K, giving rise to methane clouds in its troposphere, which gives the planet its ultramarine color. Temperatures rise steadily deeper inside the atmosphere.
Neptune has extremely dynamic weather systems, including the highest wind speeds in the Solar System, thought to be powered by the flow of internal heat. Typical winds in the banded equatorial region can possess speeds of around 350 m/s, while storm systems can have winds reaching up to around 900 m/s, nearly the speed of sound in Neptune's atmosphere. Several large storm systems have been identified, including the Great Dark Spot, a cyclonic storm system the size of Eurasia, the Scooter, a white cloud group further south than the Great Dark Spot, and the Wizard's eye/Dark Spot 2, a southern cyclonic storm.