VENUS IS A BURNING-DESERT WORLD
Planet	Water	Greenhouse	Lightning	Spacecraft	Express	Transit	Resources

Hubble Space Telescope image of Venus

Venus is one of nine known major planets of the Solar System. The others are Mercury, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. Venus is the second planet out from the Sun, between Mercury and Earth.

Venus is one of the four rocky metallic planets nearest the Sun. Those four inner planets -- Mercury, Venus, Earth and Mars -- are referred to as terrestrial planets since they are much like our own planet Earth.

Even at its closest, Venus is 100 times farther away from Earth than the Moon. Venus is the sixth largest planet.

The planet is named for the ancient goddess of beauty because it the brightest object in Earth's sky after the Sun and the Moon. Most of the features on the surface of Venus also are named for female figures.

Desert world. Venus is a burning-desert world hidden under bitter clouds of sulfuric acid and carbon dioxide. It may once have been awash with oceans of near-boiling water.

For hundreds of millions of years, most of the water on Venus was liquid near the boiling point. But the water finally dried up, according to scientists at NASA's Ames Research Center in Mountain View, California, south of San Francisco.

In what they call a moist-greenhouse or wet-greenhouse effect, the water on Venus was able to remain liquid for a few hundred million years because planet temperatures actually were cooler than Earth scientists once thought, and because of the proportion of carbon dioxide to water vapor in the atmosphere of Venus.

Images of Venus

Venusian seas dried up slowly as hydrogen eventually escaped into space. Oxygen formed compounds with other elements and was incorporated into the planet's crust.

Scientists say liquid water seems essential to life. The Ames researchers said the oceans of Venus might still have been liquid at 200 to 300 degrees Fahrenheit because of intense pressure. But that may have been too hot for life to begin. If not, it may not have lasted long enough for life to begin.

Greenhouse Effect. Venus is nearly a twin to Earth in size. However, it has atmospheric pressure on the surface 90 times that of Earth. The temperature on the surface of Venus may be as high as 900 degrees Fahrenheit.

Scientists already had a runaway-greenhouse explanation in which water existed on Venus, but only as vapor.In a greenhouse effect, Sun heat is trapped by gases in a planet's dense atmosphere.

The wet-greenhouse and the runaway-greenhouse theories have a greenhouse effect in common.

In the runaway-greenhouse explanation, Venus was said to be so hot that its water existed only as vapor and had no chance to condense to liquid on the surface. Water vapor rose into the atmosphere, where radiation from the Sun cracked it into separate oxygen and hydrogen atoms. The hydrogen escaped into space and water couldn't form.

But the Ames researchers, looking at different climates on Venus, Earth and Mars, didn't like the runaway-greenhouse explanation. That old theory forgot that the Sun was 25 to 30 percent cooler 4.5 billion years ago. It also did not account for the water loss.

NASA scientists have bounced radar waves off cloud-shrouded Venus and detected colossal highly-reflective blobs and rings that may be lava flows or volcano crater rims rich in fool's gold.

The radar survey by researchers from NASA's Jet Propulsion Laboratory (JPL), Pasadena, California, turned up more evidence that volcanoes have erupted on Venus within the last few million years, maybe even within recent centuries.

Learn more:

Venus
• Venus Planet Profile  NASA JPL
• Venus Described  SEDS Nine Planets
• Exploring Venus  STO
• Exploring Venus index  STO
• Planet Venus  STO
• Venus Water  STO
• Venus Greenhouse  STO
• Venus Lightning  STO

Venus Transit
• Venus Transit 2004  STO
• Guide to Viewing the Transit  Science @ NASA
• Guide to Viewing the Transit  Science @ NASA
• 2004 Venus Transit Resource Guide  NASA Sun-Earth Connection
• Movies and diagrams of the transit  Astronomy magazine
• Venus Transits of 2004 and 2012  NASA Goddard
• Guide to the Transit of Venus  Sky & Telescope magazine

Captain James Cook
• James Cook and the Transit of Venus  Science @ NASA
• James Cook and the Transit of Venus  Blue Latitudes
• James Cook Journals  National Library of Australia
• History of Cook's Endeavour  HM Bark Endeavour Foundation
• James Cook Transit Timing Measurements  Royal Society of London
• South Seas Voyaging  National Library of Australia
• James Cook Drawings of 1769 Venus Transit  Armagh Observatory
• Capt. Cook's Voyages  Linda Hall Library History of Science

Exploring Venus and the Solar System
• Venus Spacecraft  STO
• The Pioneers  STO
• The Voyagers  STO
• Exploring the Solar System  STO

How to watch the Sun safely
• Safe Sunwatching  Science @ NASA
• List of solar filter suppliers  Sky & Telescope magazine
• Solar Filter Safety  Sky & Telescope magazine
• Close-Up of a Star  Sky & Telescope magazine
• A Beginner's Guide to Solar Observing  Sky & Telescope magazine

Read more about the Solar System . . .
Star:	The Sun
Inner Planets:	Mercury	Venus	Earth	Mars
Outer Planets:	Jupiter	Saturn	Uranus	Neptune	Pluto
Other Bodies:	Moons	Asteroids	Comets
Beyond:	Pioneers	Voyagers