Venus - Known Facts
About Venus, what scientific facts are known including trivia about the orbit, surface, and more.
Known Facts: Because Venus's orbit is within the orbit of Earth, it always appears close to the sun. It is so bright it can be seen in the daytime if one knows where to look. Through the telescope, it shows phases like those of the moon. It is "new" when it is between Earth and the sun and we see the night side, and "full" when it is on the far side of the sun. But the telescope shows no surface features, for they are hidden by a thick veil of clouds. The atmosphere is so dense that, if it were clear instead of murky, refracting light rays would allow a person standing anywhere on the surface to see completely around the planet.
It was long felt that Venus was only slightly different from Earth, covered perhaps with lush primeval jungles. However, earlier in this century, by means of analyzing light from Venus, astronomers discovered that the planet was almost devoid of water, and that its atmosphere was 97% carbon dioxide. Furthermore, scientists realized for the first time that its air pressure must be very high.
A fuller understanding of Venus had to await two technological advances, the radio telescope and space probes. The high surface temperature was not discovered until the 1950s, and many scientists refused to believe it until it was confirmed by early space probes. It is now thought that the carbon dioxide traps heat as glass does in a greenhouse, so this is called the greenhouse effect. Radar studies have shown a much smoother planet than Earth, although there appear to be rough areas and some very large but shallow craters. The soil appears to resemble terrestrial granite. Unlike Earth, Venus has no magnetic field, perhaps because of its much slower rotation.
In October, 1975, two Soviet spacecraft, Venera 9 and Venera 10, landed on Venus and sent back pictures showing a barren, rocky surface. Despite the thick clouds, it was little darker than a dull day on Earth, and searchlights on the probes were not needed. The wind was less than 10 mph, but with the high air pressure even low winds on Venus are very powerful.
It had long been thought that the winds higher up were much stronger, and Mariner 10 confirmed this. In February, 1974. it flew past Venus and took ultraviolet pictures showing great clouds that swept around the planet in four days. The clouds being about 40 miles above the surface--four times as high as earth clouds--and some scientists think they may be composed of highly corrosive sulfuric acid, which may sometimes fall as rain--an uncomfortable thought for future explorers.
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