Venus

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Uranus (left), Neptune (right), Earth (lower left), Sirius B (lower center), and Venus (lower right). The smaller planets, Earth's moon, and dwarf planets below, in decreasing size are Mars and Mercury, the Moon, Pluto, and Haumea. All are to scale.

Venus is the second planet from the Sun. It is a terrestrial planet and the third-smallest planet in our Solar System. Venus has a diameter of 12,103 kilometers. It orbits 108 million kilometers away from the Sun. The planet's toxic but reflective atmosphere and proximity to Earth make it the brightest and most prominent planet in our night sky.

Mythology[edit]

Venus was named after the Roman goddess of love (Aphrodite in Greek mythology). the asteroid 433 Eros is named after the goddess's son. In east Asian mythology, the star was known as the "gold star" (金星), due to the planet being the brightest and shiniest in the night sky along with its yellow atmosphere. It was known, in the evenings, as the evening star in modern usage, Hesperus in Greek, and Vesper in Latin.

The Mesopotamians viewed Venus as their love, sex, and war goddess Inanna or Ishtar in Babylonia. They called her the "Queen of Heaven", a title also borrowed in other religions, and many myths based on Ishtar were based on the movement of Venus in the night sky. Ishtar was the twin sister of the Mesopotamian solar deity Shamash; both were children of the lunar deity Nanna.

The symbol for the planet Venus is identical to that of the female sex. The planet is associated with women; for example, there is the saying "Men are from Mars; women are from Venus".

Properties[edit]

Venus without its atmosphere.
Topography map of Aphrodite Regio, a high-altitude region of Venus.

Venus is the hottest planet in the Solar System. This is because of its atmosphere. 96.5% of Venus's atmosphere is Carbon Dioxide, a greenhouse gas. Because the atmosphere is highly thick, the pressure can be up to 92 times greater than on Earth, which can kill human beings. These conditions make the temperature on Venus 480 °C in temperature;[1] higher than the melting point of lead. It rains sulphuric acid on Venus. Venus is sometimes referred to as Earth's Twin planet, due to their similar size and mass. All of the surface features of Venus, which include volcanoes and lava plateaus called pancakes, are named after famous women, feminine names (such as the crater Wanda), and goddesses, except for Maxwell Montes, named for James Clerk Maxwell. Most of these were discovered by the Mariner 10 probe.

It is impossible to see the Venus's surface from space as the thick atmosphere reflects around 60% of the light that impacts it. The only way scientists are able to see it is by using infrared, ultraviolet, and radar filters. The highest point on Venus, which is among the Maxwell Montes mountain range, is higher than Mount Everest to Earth's sea level, but overall Venus has lesser variation in altitude.

Venus hosts three major high-altitude "landmasses" analogous to the Earth's continents (the planet lacks liquid oceans); called Lada Terra, Aphrodite Terra, and Ishtar Terra. Lada Terra, named for the Slavic goddess of fertility, is the smallest and is in the southern hemisphere. Aphrodite Terra is named for Aphrodite, the Greek counterpart of Venus, and is the largest, half the size of Africa and stretching across the planet's equator. The smallest "landmass" on Venus, Ishtar Terra, is named after the planet's Mesopotamian-Babylonian name (see above), is around the size of Australia, and is around the planet's north pole.

Venus has an average density of 5.2 grams per cubic centimeter. This makes Venus among the "big three" of the Solar System's planets in terms of density; the other two are Mercury and the Earth.

Rotational period, year, and having no satellites[edit]

Engravings by Francesco Fontana (in the Public Domain) showing supposed satellites of Venus that he observed, now accepted to not exist.

The planet is notable for rotating around its axis in the opposite direction ("retrograde") as opposed to the other planets; Uranus does this too but due to its axial tilt this is less obvious.

The period of time it takes for Venus to rotate around its axis is longer than the planet's orbital period. Venus orbits the Sun roughly 224,7 Earth days, but rotates very slowly around its axis every 243 Earth days. Hence a day is longer than a year. The reason for such a slow and backwards rotation is likely due to a collision with another celestial body, such as a protoplanet or comet. This potential collision could also explain why Venus has no moons; if a collision caused Venus to rotate backwards, any orbiting satellites would have lost momentum and thus spiral back and collide with Venus.

While it is now established that Venus has no satellites, it was suspected (first by Giovanni Cassini) in the 1600s that Venus might have one, believed to be found through telescopes. This satellite was alternatively theorized by Jean-Charles Houzeau to be a planet that orbited the Sun every 283 days and be in conjunction with Venus every 1080 days, which fitted with the recorded observations of the suspected "moon" so far at the time. He also named the supposed moon Neith after a creator and Athena-like Egyptian goddess. By the 1700s, the moon's existance had already been ruled out.[2]

Transit of Venus[edit]

Venus can pass (transit) in front of the Sun; the last time this happened was in 2012. When transits occur, a "black drop" effect produced by the planet's atmosphere can be observed. Transits usually are hours long and are separated by periods on the order of hundreds of years.[3]

References[edit]


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