The Living Planet Of course we know the third planet from the sun. It’s our planet, Earth. From up here, it looks like a blue marble. T at’s because oceans cover nearly three-fourths of our planet. Earth is the only planet known to have liquid water. Earth also has just the right temperatures
for life. Our atmosphere is just right, too. It has enough oxygen for us to breathe and gases that protect us from the sun’s harmful rays. Neither Mercury nor Venus has a moon,
but Earth does. A moon is a natural object that orbits a planet. Now it’s time to head to the fourth planet.
The Red Planet On Mars, wispy clouds and patches of pink mist form in the thin atmosphere. In many ways, Mars is most like our own planet. Even the length of its day is similar. A Martian day is just 41 minutes longer than a day on Earth. People haven’t walked on Mars yet, but
Venus’s atmosphere traps the sun’s heat.
today, you’re going to land there. As you touch down in a rocky valley, you see a spinning orange dust devil. T ese dust storms form when warm air rises. Like tiny tornadoes, they scatter dust across the planet. T e rocks and soil in this valley are rich in iron minerals. T ey have a reddish color to them. You might like to get out and walk around,
The Hottest Planet Mercury may be closer to the sun, but Venus is hotter. It isn’t a very welcoming neighbor. Venus’s thick atmosphere traps the sun’s heat. It’s made up mostly of carbon dioxide. Its clouds are coated with acid. Beneath the clouds, Venus’s rocky surface
floats on melted rock. T is magma bursts through to the surface oſt en, forming huge volcanoes. Venus has more volcanoes than any other planet in the solar system. You’d better not try to land. Not only would
you have to dodge spewing volcanoes, you’d also get squashed. T e air on Venus is thicker than Earth’s. It would crush your spacecraſt like a soda pop can. So keep fl ying.
12 NATIONAL GEOGRAPHIC EXPLORER
but you’d better not. It’s very cold here. You also can’t breathe here. Too much carbon dioxide makes Mars’s air poisonous. You need to take off and keep moving. You’re about to see the largest planet in the solar system.
The Largest Planet Jupiter is larger than all the other planets in the solar system put together. Don’t let its size fool you, though. T is planet can really move. It spins once every 10 hours. T at’s the shortest day in the solar system. Jupiter’s rapid spin creates rough weather.
Whipping winds race across the planet. One swirling storm, called the Great Red Spot, has raged for hundreds of years.
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