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Mercury
We are approaching the second smallest planet, the planet closest to the sun. The ancient Romans named it Mercury in honor of the swift messenger of their gods. It travels about 30 miles per second. At that speed, Mercury goes around the sun, or REVOLVES, in only 88 Earth days. The Earth takes 365 days for its year.
Mercury spins on its axis, or ROTATES, as it is revolving. On Earth, a rotation takes 24 hours, or 1 day. On Mercury a rotation takes 59 Earth days. Since a year is only 88 Earth days, there are less than 2 long days per year on Mercury. Can you imagine how long you'd have to stay at school on a Mercurial day?
Look! We are close enough now to see the surface of Mercury. Notice how much it resembles the Earth's moon. Scientists believe it hasn't changed very much since the beginning of the solar system, although it may have once had volcanoes. Can you see the hundreds of craters? Since Mercury has only a very small amount of helium and other gases, there has been little to keep the meteors from crashing into the planet. On Earth more than 100 million meteorites enter the atmosphere each day, but they burn up due to friction.
All right, passengers please be seated and fasten your safety belts. We are approaching Mercury's gravity field. Although Mercury's force of gravity is only 1/3 that of the Earth, we've been weightless for a while, and we'll notice the difference. Prepare for landing. Shwishhhhhhhhhhhhhh Boomp!
We have landed on Mercury, Ambassanauts. In a moment, we will be leaving our ship for a short walk here on Mercury. We chose to land on the day side of the planet. Your suits will protect you for a short while from the 430 degree C temperatures. The night side would have been MINUS 170 degrees C.
The first thing that you'll probably notice is that the sky is black. With no atmosphere to reflect the sun's light, you can even see the stars today. Look up into the sky. The sun is about 2½ times as large as we see it on Earth. Remember not to stare at the sun! It could really burn your eyes!
Did you notice that your compasses work here? Mercury has an iron core much like Earth's. A compass will only work where there is a magnetic field. Do you remember what the Earth's magnetic field looks like?
Have you tried jumping? You won't be able to hop as high as you did on the Moon, but a 100 lb. Person will only weigh 33 lbs. here. Let's take a quick walk over to see that crater. Wow! It's about 200 kilometers across. That's too far to walk even in a Mercurial day.
What's that, you're thirsty already? There's no water here--only a thin coating of dust everywhere. This is probably as long as it is safe to remain here in our EMU's, anyway. Let's return to the ship while we're all still safe.
As we leave Mercury, I want you to look once more. What do you see? Did you see a moon? Did you see any sign of life? This would be a good time to take a picture.
Problem 1: What is friction?
Problem 2: Why is it dangerous to be in the sun too long?
Problem 3: How do magnets work?
Problem 4: Why is the sky on Earth blue and the sky on Mercury black?
Oh no! Our power has gone out and it's time to fix dinner. Do you think we could use the sun's energy to help us solve our problem?
Would it work better on Earth or in space?
Why?
Statistics for Mercury
Diameter ...... 3031 miles (4880 km)
Number of Natural Satellites ...... 0
Mean Distance from the Sun ...... 35,974,272 miles (57,910,000 km)
Rotational Period (day)...... 58.65 days
Orbital Period (year)...... 87.97 days
Inclination of Axis ...... 0 degrees
Mean Surface Temperature ...... 354° F (179° C)
Main Atmospheric Component ...... Helium
Atmospheric Depth ...... negligible
Apparent Magnitude ...... -1.9
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Venus
We're off again. I'd like you all to look out of your porthole toward Earth. Can you see that lovely, bright planet between Mercury and Earth? As seen from the Earth, it is the brightest planet in the night sky. Sometimes we see it in the morning and sometimes we see it in the evening. The Romans named it Venus in honor of the Roman goddess of love and beauty.
Venus takes about 225 days or 7½ months to go around the sun once--its year. Like Mercury, Venus spins on its axis slowly. As a matter of fact, a day on Venus is longer than a year on Venus, 243 Earth Days. And it's the only planet that rotates backwards, like a top spinning the opposite direction of all the other tops.
Although Venus is known as the Earth's twin, the similarity is basically one of size. As we approach Venus, you will notice a thick cloud cover preventing us from seeing any land formations. At one time, scientists think that Venus was very similar to the Earth--with temperate climate and even water. But as the sun got hotter, the water boiled off. Volcanoes spewed carbon dioxide into the atmosphere. The carbon dioxide captured the heat from the sun's rays and wouldn't let it go, creating a greenhouse gone berserk. As a result, the surface of Venus is much hotter than that of a broiling household oven. It is hot enough to melt lead! Venus is the hottest planet, even hotter than Mercury.
Venus has a thick carbon dioxide atmosphere that weighs 1352 pounds per square inch. On the Earth, a square inch of air weighs 14.7 pounds per square inch. We might feel a little like being at the bottom of an elevator filled with elephants. We will need our pressure suits for sure!
Those beautiful clouds are made of sulfuric acid. Sulfuric acid is a very strong acid which is sometimes used in making batteries. Would you like to guess what the air would smell like if we tried to sniff it? Rotten eggs!
Fasten your seatbelts. We're about to land on Venus!
Step carefully. It's hot here, but it's beautiful. Look over there. See the sheets of smooth lava flows? We're on Aphrodite Terra, Venus'largest continent--larger than North America and Africa put together. Off to your left is a band of volcanic cinder cone mountains. Venus lets heat out of her rocky core through her hot spot volcanoes. Look at the way the mountains are shaped, though. VISCOUS CREEP looks like Silly Putty spreading out. It's as effective as water erosion in reducing mountains on Venus. It is caused by the super hot rocks slowly flowing downhill.
You won't weigh much less here on Venus than you did on Earth since Venus is about 4/5 the size of Earth. If you weighed 100 pounds on Earth, you'd weigh 89 pounds here.
Watch out for those lightning flashes! We'd better get back to our ship! We should have expected those, though. There are almost always lightning storms on this planet. It won't help us find a drink, however. It's a good thing we brought plenty of our own water with us.
Safely back in our ship, let's take a picture of this beautiful, violent planet. Did you see any sign of life? Did you see any moons? Would this be a good place to start a new space colony?
Problem 1: Venus is not the closest planet to the sun, but it is the hottest. Why do you think this is so?
Problem 2: One of the ways in which the land is worn away on Venus is by a process called viscous creep. Exclusive to Venus, this type of erosion is caused by hot rocks melting downhill. What are the primary methods of erosion on Earth?
Problem 3: On Venus there are constant lightning storms. What is lightning?
Problem 4: When your mother bakes a cake, she uses several ingredients that go together to become cake. All matter is made of ingredients. Those ingredients which can't be taken apart any further and still be themselves are called elements. Scientists have a universal shorthand for discussing the elements and their combinations. What is the Periodic Table of Elements and how does it work?
Problem 5: Can anyone show me how large a square inch might be? Now look up. Pretend that you can see all the way up to where space begins. For each square inch, there is a column of air which goes all the way up to the end of the atmosphere. And since air is STUFF, and all matter has weight, that air has to weigh something. On Earth, it weighs 14.7 pounds. The atmosphere is different on each planet. Because it is different matter, it has different weights on different planets. Some places, like Venus, the pressure is so great that it would crush us. The atmosphere has different weights for another reason, too. Do you know what that is?
Problem 6: Photosynthesis is the process by which plants make their own food. They use carbon dioxide and give off oxygen in the process. Could plants and photosynthesis help scientists recover the atmosphere of Venus is the future?
Mars
We just passed Earth and already we can see surface details of the Red Planet. The ancient Romans names Mars after their bloody god of war. After our last stop at Venus, though, Mars should seem quite peaceful.
Mars is halfway between the Earth and the Moon in size. That means that only Mercury and Pluto are smaller. A year on Mars is 687 Earth days long. Do you remember whether that is longer or shorter than an Earth year? Mars rotates once every 24 hours and 37 minutes. The Earth rotates once every 23 hours and 56 minutes. Pretty close! We'll feel more at home on Mars than we have since we left home.
Many scientists think that Mars was once much like the planet Earth. The temperature was close to the temperatures we experience on Earth, and there was plenty of water. But the carbon dioxide in the atmosphere was used up and not replaced. Mars could not make use of the Greenhouse Effect as Venus and Earth do, so the water froze. With only half the amount of energy that the Earth gets reaching Mars, there was just not enough heat to warm the planet.
The temperature of Mars today averages about 30 degrees C. The atmosphere contains only a trace of oxygen. Scientists think that the water may be frozen as the North Polar Cap, permafrost, and groundwater. The South Polar Cap is probably dry ice, frozen carbon dioxide.
Fasten your safety belts. Prepare for a landing. Schwissssssshhhhhhh! That was a nice gentle one! You might want to bring along your sand buckets on this trip.
Look around you. Does it look familiar? Other than the fact that everything is red, the landscape should remind you of Death Valley, California, Earth. http://search.gallery.yahoo.com/search/corbis?p=death+valley There is a lot of dust here, but there are also jagged chunks of rock. Don't trip on them. We're lucky the wind is not too strong today. Some days it blows so hard that the dust practically blocks out the sun. Scientists think something like that might happen on the Earth is there were a large scale nuclear war. If it did, the warming rays of the sun would not be able to reach the land for six months or more. Can you imagine what that would do?
Look off in the distance. Do you see that hump? It's far away, but it is ten kilometers high. Right! That is Olympus Mons, the largest volcano in the whole solar system. It is one of the hot spots on Mars. Olympus Mons may erupt every 10,000 years. Wouldn't it be exciting to see that from our space ship?!
If you're feeling kind of light here, the gravity of Mars is only about 40% of that on Earth. That means that if you weighed 100 pounds on Earth, you would weigh only 40 pounds. The atmospheric pressure is a mere .15 pounds per square inch. A real relief after Venus!
Did you see those beautiful Martian clouds? The pink clouds are dust clouds. The thin blue clouds are made of ice crystals. The rare, thick white ones are made of water vapor.
Now watch the sky. If you look carefully, you'll be able to see the two moons of Mars, Deimos and Phobos. If all goes well, we'll try to stop on Deimos for a short visit.
Fill your buckets with some souvenirs and we'll return to the ship. The rest we can see better from aloft.
Everyone ready? As we lift off, notice the canyons, gorges, and dry river beds. Do you see the different colored areas of Mars? These change with the seasons. We should be high enough now for you to see those striking, white polar regions. If only we knew the mysteries they keep.
Quickly now, take your pictures before we are at Deimos. It won't take any time at all.
Problem 1: Mars has areas which look like they were formed by running rivers. Erosion is the wearing away of the land. Mars shows evidence of erosion by what two means?
Problem 2: There is no running water on Mars, but scientists think that water may be on the planet in another form. Matter can exist in three states: solid, liquid and gas. How does matter change from one state to another? Do you think it will change states again on Mars? Explain your answer.
Problem 3: Scientists think that Mars, Earth, and Venus may have had similar conditions when they first started out. The use of carbon dioxide caused very different results. What does carbon dioxide do?
Problem 4: On Earth today, we are polluting the air by burning coal, oil, and gas. This has the effect of increasing the Greenhouse Effect and causing acid rain. What do you predict will happen on Earth if we do not care for our planet?
Problem 5: On Mars there are great windstorms which block the sun's rays. Scientists are concerned that a nuclear war could cause an effect similar to the sunblocking windstorms on Mars which might last for six months or more, killing all vegetation. Some scientists even think that such dust storms, caused by meteorite impacts, may have already occurred on Earth. When do you think that might have happened?
Problem 6: On a long space voyage, it would not be practical to carry all of the fresh water needed for the trip. One suggestion for conservation of water is recycling. Water on Earth goes through a natural recycling process called the Water Cycle. Explain the water cycle.
Problem 7: If you did not empty the garbage cans in your home for a couple of weeks, you would probably have quite a bit of garbage. Can you imagine how much garbage would accumulate during the course of a space voyage? What do you think the effects of improperly disposing of wastes in space might be?
Deimos
Have you ever wondered why all the planets and their moons look like balls--big round spheres floating around out there in space? When you see Deimos, you may have a different question. Why doesn't Deimos look like a sphere? Look out your porthole. You can see it now! Do you see that smashed, bashed, potato-shaped moon out there? Deimos actually looks like a piece of a planet--and maybe it is. Many scientists think that the asteroids may be chunks of a planet that never formed, and they think that both Deimos and Phobos, the two moons of Mars, are captured asteroids. The gravity is extremely low on Deimos. You only have to go about 22 miles per hour to escape Deimos' gravity (that's its escape velocity) and a good running jump could put you in orbit. The escape velocity on Earth is almost 25,000 miles per hour.
Gravity does more than keep YOU on the planet. Gravity also pulls the mountains back down to level and knocks off the uneven spots. We call this action EROSION, and it's going on all of the time. Unfortunately, though, Deimos' gravity is not strong enough to make it round.
Fasten your seat belts. It's time to land. Schwisssfffft.
Before you leave our space ship, remember to fasten your tether. Then you can have some fun getting the kinks out of your muscles without launching yourself into outer space.
Look around you. Do you see all of the craters here on Deimos? They are filled with debris, as though the moon had been showered with powder. That is probably a result of numerous explosive meteorite impacts. We won't stay long on this moon, since we never know when another meteorite will make a surprise landing.
Atmosphere is almost nonexistent here, too. Gravity, or lack of gravity, is the reason, again. It takes gravity to hold down an atmosphere.
Notice that the sun is not as large here as it was on Earth. What do you think that big, red sphere in the sky is?
It's time to get on with our journey, so everyone back to the space ship, and don't trip on a crater!
Draw Deimos
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