(c) Anthony K. Grafton 2003

Our Solar System, Part 3: Venus: Earth’s Harsh Twin

Some have said that Venus is the planet in our solar system that is most similar to Earth. It is almost the same size and its structure is not very different from Earth, but the similarities end there.

Venus has the hottest surface temperatures of any planet in our solar system, hotter even than Mercury, which is closer to the sun. Temperatures on Venus can reach several hundred degrees in the daytime.

Part of the reason that Venus gets so hot is because of its dense atmosphere, which is made almost completely of carbon dioxide. The abundance of this gas on Venus has led some to compare this planet to a future vision of a greenhouse-gas-warmed Earth. So-called “greenhouse” gases like carbon dioxide tend to trap heat from the sun, and so the atmosphere of Venus tends to absorb hold in heat very well.

Besides contributing to the heat, the atmosphere on Venus has an enormous pressure: almost ninety times that of Earth’s atmosphere. These incredible pressures crushed some of the early probes humans sent to the planet while the high temperatures scorched them.

Two scientists in Texas, Dr. Dirk Schulze-Makuch and Dr. Louis Irwin, recently studied some of the data that has been gathered about Venus. They have noticed that Venus has certain unusual compounds in its atmosphere that don’t normally exist together. One possible way to explain the existence of these chemicals, they say, would be if life exists in Venus’ atmosphere. They suggest that life could have evolved millions of years ago on Venus, but because of the incredible heat, the only remaining life forms might be microbes in the planet’s atmosphere.

Not counting the sun and the moon, Venus is the brightest object in our sky. It is sometimes called the Morning or Evening Star because it is so easily seen during those times. With a good pair of binoculars or a small telescope, you can even observed the phases of Venus like those of our moon. Can you point out Venus in the night sky?