PASSAGE 4
(Professor) Today we’ll be discussing the planet Venus, which is the second planet in our solar system. I’m sure you all know which planet is the third planet in our solar system. Yes, Beth?
(Beth) Is Earth the third planet?
(Professor) You don’t sound too sure of your answer, Beth…but, yes, that’s true. Venus is the second planet in our solar system, and Earth is the third. Venus is almost the same size as our Earth, which is the fifth largest planet in, ah, the solar system. The planet Venus is easily visible in the sky from Earth, although not always as a complete sphere. It goes through some phrases, just like the Moon. Sometimes it’s fully visible, like a full moon, sometimes it’s half visible, and sometimes it’s only a small crescent. When do you think Venus is the brightest, when it’s fully visible or when it’s a crescent? Mark?
(Mark) Well, it makes sense that it would be the brightest when it’s fully visible.
(Professor) Well, things aren’t always as they seem. Try again.
(Mark) You mean, Venus is actually brighter when it’s only a small crescent than when it’s fully visible?
(Professor) That’s exactly what I mean…. Now, does anyone know if Venus is a hot or cold planet?…What would you expect since Venus is closer to the Sun than our planet is?
(Beth) Since it’s so close to the Sun, I think it would be very hot.
(Professor) And it is. The temperature there can reach almost to 500 degrees centigrade. What is this in Fahrenheit?…
Anyone?…Come on, we’ve talked about this before.
(Mark) I think that’s around 900 degrees Fahrenheit.
(Professor) Yes, it is. Now, we’ve said that the temperature on Venus is quite hot, and the temperature there is hot because Venus is so close to the Sun. But that’s not the only reason that Venus is so hot. It’s also hot for another reason. Does anyone know? Could it be the atmosphere? What is its atmosphere made of? Beth?
(Beth) Its atmosphere’s almost entirely carbon dioxide.
(Professor) Yes, that’s right, Beth, and this type of atmosphere holds in the heat from the Sun extremely well….Now, let’s talk about the clouds that cover Venus. As you know, Venus is visible to us on Earth, but it’s not actually the planet that we see; it’s the clouds. The surface of Venus can’t be seen, even with a telescope, because of the clouds that surround the planet. What can you tell me about the clouds that cover Venus?
(Mark) Uh…the clouds around Venus?
(Professor) Yes, I’m asking about the clouds around Venus. I want to know about the clouds around Venus.
(Mark) Do you want to know what they’re made of? They’re made of carbon dioxide. No…wait a minute. The atmosphere’s made of carbon dioxide…. The clouds are made of sulfuric acid.
(Professor) That’s right. The clouds on Venus are actually made of sulfuric acid. These clouds help to contribute to the brightness of Venus in our sky. When Venus appears to shine so brightly, it’s because the light of the Sun is reflecting off Venus’s clouds of sulfuric acid.