The following questions were answered by astronomer Dr. Cathy Imhoff of the Space Telescope Science Institute.

How big is Venus?
Venus is almost the same size as Earth! It is just a little bit smaller. That is why we sometimes think of Venus as Earth's twin (although it is much hotter and has a very different atmosphere, but hey, that's just on the outside!).

When was Venus discovered?
Venus has been known to people for thousands of years. It was probably a caveman who first noticed "the morning star" and "the evening star."

What is the atmosphere like on Venus?
The atmosphere is very thick. On the surface, the pressure is very high — about 90 times Earth's! This would be like being at the bottom of our oceans! The light from the sun is also filtered by the thick atmosphere — it would look very murky.

Venus is a NASTY place! It has an atmosphere of carbon dioxide (96%), nitrogen (4%), and traces of various things including sulfuric acid! The acid seems to be mostly in the atmosphere, although it may sometimes rain.

Could people ever live on Venus?
The U.S. and Russia have both sent spacecraft to land on Venus. They have to take measurements quickly before the spacecraft fall apart! The climate is so bad that the equipment fails after a while — eaten by acid or crushed by the atmosphere. So I don't think that people will go there any time soon.

Does Venus have any moons?
No, Venus doesn't have any moons.

Why is sulfuric acid in Venus's clouds?
I think the sulfuric acid in Venus's clouds comes from volcanoes. Sulfuric gases are given off by volcanoes from the earth as well as from Venus. But on Venus the sulfur gases mix with other gases to form sulfuric acid, which condenses and falls from the sky like a terrible acid rain. Yuck!!!!

In a book it says Venus's atmospheric pressure at the surface is 90 bars (90 times higher then Earth's). What does that mean?
Well, it means that the pressure — the weight of Venus's thick atmosphere — pushes on things 90 times more than on Earth. This would be about 1,300 pounds per square inch — a crushing weight! Sounds very unpleasant! My book tells me that this is about the same as if you were over a half mile down in the ocean.

Do Mercury and Venus ever get between Earth and the sun? If so, what is it called?
Yes, this happens — it is called a "transit." Since the planets are so much smaller than the sun, they look like a small black dot moving across the face of the bright sun. A transit of Mercury happens about 13 times in 100 years. Transits by Venus are rarer. There were two back in 1874 and 1882. The next ones you and I may see — they are coming up on June 8, 2004, and June 6, 2012.