Venus vs Neptune - Comparison

Venus is the second planet from sunlight. It is named after the Roman goddess of love and beauty. As the thing in the night sky after the Moon, Venus may be, on occasion, visible to the naked eye in broad daylight and can cast shadows. Venus lies within Earth's orbit, and never appears to venture either setting in the west just after dusk or rising in the east a bit before sunrise. Venus orbits the Sun every 224.7 Earth days. Having a rotation period of 243 Earth days, it takes longer to rotate about its axis than any other planet in the Solar System and does so in the opposite direction to all but Uranus (meaning that the Sun rises in the west and sets in the east). Venus does not have any moons, a distinction it shares only with Mercury among planets in the Solar System.Venus is a terrestrial planet and is sometimes called Earth's"sister planet" because of their similar size, mass, proximity to the Sun, and bulk composition. It is different from Earth in different respects. It's the atmosphere of the four planets, consisting of over 96% carbon dioxide. The atmospheric pressure at the planet's surface is 92 times that of Earth, or roughly the pressure found 900 m (3,000 feet ) underwater on Earth. Venus is by far the hottest planet in the Solar System, with a mean surface temperature of 735 K (462 °C; 863 °F), even though Mercury is closer to the Sun. Venus is shrouded by an opaque layer of reflective clouds of sulfuric acid, preventing its surface from being seen from space in light.

It might have had water oceans before, as the temperature rose because of a runaway greenhouse effect but these could have vaporized. The water has photodissociated, and the hydrogen that is free has been swept into space by the solar wind due to the lack of a planetary magnetic field. Venus's surface is a sterile desertscape interspersed with slab-like rocks and is periodically resurfaced by volcanism. Venus has been a significant fixture in human civilization for as long as records have existed. It has been made sacred to gods of many cultures, and has been a inspiration for writers and poets as the morning star and evening star. Venus was the first planet to have its motions plotted across the sky, as early as the second millennium BC.As the planet with the nearest approach to Earth, Venus has been a prime target for early interplanetary exploration. It was the first planet beyond Earth visited by a spacecraft (Mariner 2 in 1962), and also the first to be successfully landed on (by Venera 7 in 1970). The thick clouds of venus render observation of its surface impossible in visible light, and the detailed maps did not emerge before the Magellan orbiter's coming in 1991. Plans have been proposed for more complex missions or rovers, but the hostile surface conditions of Venus hinder them. In January 2020, astronomers reported evidence that suggests that Venus is volcanically active.

Source: Wikipedia

<p>Neptune is the eighth and farthest known planet from the Sun in the Solar System. </p>In the Solar System, it is the fourth-largest planet by the third-most-massive planet diameter, and the densest giant planet. Neptune is 17 times the mass of Earth, slightly more massive than its near-twin Uranus. Neptune is physically smaller than Uranus and thicker because its mass causes gravitational compression of its atmosphere. Neptune orbits the Sun once every 164.8 years at a mean distance of 30.1 AU (4.5 billion km; 2.8 billion mi). It is named after the Roman god of the sea and has the astronomical symbol ♆, a stylised version of the god Neptune's trident. Neptune is not visible to the unaided eye and is the only planet in the Solar System found by forecast as opposed to by empirical observation. Changes in the orbit of Uranus directed Alexis Bouvard to deduce that its orbit was subject to gravitational perturbation. The position of Neptune was calculated from Bouvard's observations by John Couch Adams and Urbain Le Verrier following his death. Neptune was observed with a telescope on 23 by Johann Galle within a degree of the position predicted by Le Verrier. Though none of the remaining 13 known moons of the planet were located before the 20th century its largest moon, Triton, was discovered soon thereafter. The distance from Earth of the planet gives it a very small apparent size, which makes it challenging to research with Earth-based telescopes. Voyager 2 visited neptune, when it flew by the planet on 25 August 1989; Voyager 2 remains the only spacecraft to visit Neptune.

The advent of the Hubble Space Telescope and large ground-based telescopes with adaptive optics has allowed for further observations from afar. Like Jupiter and Saturn, Neptune's atmosphere is composed primarily of hydrogen and helium, together with traces of hydrocarbons and possibly nitrogen, even though it includes a higher proportion of"ices" such as water, ammonia and methane. However, similar to Uranus, its interior is primarily composed of ices and rock; Uranus and Neptune are normally considered"ice giants" to emphasise this distinction. Traces of methane in the outermost areas in part account for the world's blue appearance.In contrast to the hazy, relatively featureless atmosphere of Uranus, Neptune's atmosphere has visible and active weather patterns. For example, in the time of the Voyager 2 flyby in 1989, the world's southern hemisphere had a Great Dark Spot comparable to the Great Red Spot. These weather patterns are driven by the strongest sustained winds of almost any planet in the Solar System, with recorded wind speeds as high as 2,100 km/h (580 m/s; 1,300 mph). Due to its great distance from the Sun, Neptune's outer atmosphere is one of the coldest places in the Solar System, with temperatures in its cloud tops approaching 55 K (−218 °C; −361 °F). Temperatures in the world's centre are approximately 5,400 K (5,100 °C; 9,300 °F). Neptune has a faint and fragmented ring system (labelled"arcs"), which was discovered in 1984, then afterwards confirmed by Voyager 2.

Source: Wikipedia