Astronomy Packet: 3
Now that you have seen how these three planets are similar in some ways, let's explore each one by itself.
Even though Venus is made up of almost the exact same elements as the Earth, it has evolved very differently. Long ago both Venus and Earth had atmospheres which were full of a gas called CO2, or carbon dioxide. Carbon dioxide is the gas responsible for the greenhouse effect. On Earth, our oceans dissolved much of the CO2 and deposited it in the sea beds. Plants also help to reduce the levels of CO2.
On Venus, however, this did not happen. Venus is closer to the Sun and so it is a bit warmer. The oceans of Venus began to evaporate much quicker than they do on Earth. Venus' oceans became smaller and smaller. Because there was not a large ocean to dissolve the CO2 out of the atmosphere, the greenhouse effect continued to raise the temperature hotter and hotter. Eventually the oceans on Venus disappeared completely. Venus still continues to get hotter and hotter, today it is about 800°F (426°C).
Assignment # 3:
Today we are adding CO2 to our atmosphere by burning gas in cars, planes and factories. Do you think it is important to be careful about how much CO2 we add to the atmosphere? Why or why not?