Facts about Venus

• Second planet from the Sun
• It’s a Terrestial Planet & the hottest planet

Diameter: 7,521 miles
Mass: 0.82 Earth’s mass
Density: 5.25 where water = 1
Gravity: 0.9 times that of Earth
Albedo (% of Sunlight reflected): 65%
Rotation on Axis: 243 days
Inclination of Axis to Orbit: 177.4°

Distance from Sun: 67,230,000 miles
Revolution about Sun: 224.7 days
Inclination of Orbit to Earth’s Orbit: 3.4°

Atmosphere: 96% Carbon dioxide, 2.7% Nitrogen plus traces of Argon and Oxygen
Surface Temperature: 900° F
Atmosphere Pressure: 90 times that of Earth

Moons: Venus has no moons.

Most interesting features in a small telescope: With any small telescope at just 50x, you can observe Venus in one of its phases. Since it it totally covered in clouds, no surface features are ever visible and it is not possible to see subtlies in the clouds as in the picture to the right. Venus is a crescent when it is the brightest in the sky and this is a pretty sight!

THE PLANET VENUS

One cold, moonless, winter night in Milwaukee, I went outside to look at the stars. Snow covered the back yard and Venus was high and bright. Something that night seemed different. I noticed the shadows of the lilac branches, plainly visible on the snow. Venus was casting shadows!

Venus has the distinction of being the brightest Planet in our sky, reaching magnitude –4.6. It is often referred to as the morning or evening star because it hugs close to the Sun’s rising and setting. Since Venus orbits inside Earth’s orbit, it also cycles through phases.

In the past, Venus was referred to as Earth’s sister Planet because the diameters of the two Planets are almost the same. This connotation vanished when we discovered that Venus is totally inhospitable to life; so much so, that even scientific probes can last only several minutes on its surface. Its atmosphere is 96% carbon dioxide with temperatures soaring over 900° F. This temperature is more than hot enough to melt lead, zinc or tin. Its atmospheric pressure is 90 times Earth’s, equivalent to water pressure at 3,000 feet below sea level. Venus’ day is longer than its year, and in comparison to all the other Planets, it rotates on its axis almost upside down.

Locating and Observing Venus
Venus is very easy to find in the sky because of its brightness and close proximity to the rising or setting Sun. Reaching magnitude –4.6, Venus easily outshines all the other stars and Planets. If you see a very bright star lower in the sky during the early morning or night, it will almost always be Venus. When Venus is shining it brightest, it can seem eerily bright.

With a small telescope and moderate magnifications of 50x to 100x, Venus appears brilliantly white and featureless because of its thick cloud cover. Since this Planet is inside Earth’s orbit, it cycles through phases just like the Moon. However, unlike the Moon, it varies in size. Venus is at its largest and brightest when a crescent. The crescent phase of Venus can be seen in well-focused binoculars.

The surface of Venus imaged using radar from spacecraft that were placed into orbit. Venus has active volcanoes that provide flowing lava.

An image of Venus’ surface from the USSRs’ spacecraft Venera 9 in 1975. Transmission lasted only 53 minutes from the surface because of Venus’ extreme temperature and pressure. Click on the picture to see the full scan.

Phases of Venus. Venus cycles through phases because it orbits inside Earth’s orbit. It is a crescent when it is at its brightest.

What’s Out Tonight? is sponsored by Ken Press, publisher of astronomy books and charts.
Phone: (520) 743-3200 • Fax: (520) 743-3210 • Email: ken@kenpress.com