Davis Casey, age 13, .of Bridgeport, Connecticut, for his question:

What sort of atmosphere has Venus?

On March 1st of last year, the Russian space craft Venus III landed with a bang on the surface of the planet Venus. It was expected to relay back data on the dense atmosphere. But its instruments failed. Our knowledge of cloudy Venus has been gathered by a variety of other space probes.

The surface of golden Venus is so thickly veiled in dense clouds that it has never been seen by human eyes. The most powerful telescope cannot pierce the dense atmosphere and photograph its surface. This situation is very tantalizing to astronomers, especially since Venus comes closer to us than any other planet. A variety of probes have been used to solve the nature of the atmosphere of Venus, but the details steal are shrouded in mystery. However, every successful attempt adds a little more information. And, as a  rule, each fruitful try poses a few possibilities to be checked by future probes.

The first sizable mass of data was gathered by our spacecraft Mariner II on December 14, 1962. This little space prober brushed past Venus at a distance of 21,700 miles with its instruments working in top form. It relayed back to the waiting world data on clouds and gases, temperature and magnetic fields. It scanned a zig zag area up the dark side of the shrouded planet, down the twilight zone and up the sunlit side. The atmosphere was reported to be 10 to 20 times~thicker than our own.

The clouds in the dense atmosphere begin about 45 miles above the surface. And they cloak the entire planet in a thick, smoggy blanket. The sun is never visible from the surface of Venus, though plenty of sunlight filters through.. The cloudy carbon dioxide, hydrocarbons and other gases transform much of the sun's radiant energy into heat    and the dense, smoggy blanket prevents the heat from escaping. Mariner II reported that the temperature on the surface of Venus is about 800 degrees Fahrenheit. It was the same in the three zones of daylight, darkness and twilight.

In 1964, a high altitude balloon carried a special telescope more than 16 miles above New Mexico. Its instruments were planned to check the water vapor in the atmosphere of Venus. At this level, it was above much of the normal interference from our own airy gases.

There is some, but not much water vapor in the gaseous veils of Venus. The vapor present in the upper cloud: layers was estimated to be enough to cover the surface of the planet with a layer of water 0.0039 inches deep. This is hardly enough moisture to form a filmy dew. There may or there may not be heavier concentrations of water vapor in the center of the dense cloud layer or even in the gaseous atmosphere below the cloud level.

There is not enough water vapor around Venus to support life as we know it on earth. What's more, there is little if any of the life giving gas, oxygen. Even if creatures could survive under these conditions, they would have to endure temperatures hot enough to melt tin, zinc and lead. Though Venus has at least 10 times more atmospheric gases than we do, its abundant atmosphere is not friendly to earthlings.

A lot of information about Venus has been gathered by radio telescopes. The strong signals suggest that the surface is rough and mountainous. One big problem in studying the planet has been the rotation period. A recent probe taken by radar indicates that the day and night period on Venus equals 243 earth days. The Venusian year is 224.7 earth days. On Venus, the day is somewhat longer than the year. And with slight variations, the same side of the golden planet always faces toward the earth.

The following are statistics on the Planet Venus:

Planetary Symbol: Name in Roman/Greek Mythology: Venus/Aphrodite

Diameter: 12,104 km (7,522 miles)

Rotation Period about Axis: 243 days (retrograde)

Mass: 4.87x10^24 kilograms (0.82 x Earth's)

Revolution Period about the Sun: 0.62 years

Density: 5,243 kg/m^3 Tilt of Axis: 177-178o

Minimum Distance from Sun: 108 million km (67 million miles)

Surface Gravity: 8.87 m/s^2 (0.90 x Earth's)

Maximum Distance from Sun: 109 million km (68 million miles)

Average Temperature (C/F): 457o C (855o F)

Average Surface Temperature (K): 730K

Orbital Semi-major Axis: 0.72 AU (Earth=1 AU)

Minimum Distance from Earth: 40 million km (25 million miles)

 Satellites: 0