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Venus, our sister planet | Brantford Expositor

Venus and Earth are virtual twins when it comes to composition and size, but both planets are the same as chalk and cheese.


Recently, I had the pleasure to visit several classes to make astronomical presentations. I've done a lot of them and it seems like it's the time of year when classes 6 and 7 learn about the solar system. Standing in front of the class brought me a lot of memories, sitting many years ago in the classroom, learning the wonders of the universe.

Several slides I used to show comparisons between planets, especially their sizes. One striking similarity showed a comparison between the size of Venus and Earth. These two planets are virtual twins when it comes to composition and size, but both planets are the same as chalk and cheese.

Venus circulates closer to the Sun than Earth, about 108 million kilometers from the Sun, compared to about 150 million kilometers for the Earth. In this way, Venus revolves around the Sun around 73% of the Earth's distance.

One of my slides at school showed the transit of Venus. It is then that the Earth's orbit and Venus level out, and Venus seems to intersect the disk of the sun. An interesting part of this is that when Venus is almost the same size as Earth, it is wonderful that a small dot on the surface of the sun represents the same size as the Earth with all its people on it. This shows how big is the comparison of the sun with Earth and Venus.

Despite similar size and orbits, Venus and Earth could not be further away in terms of the conditions that exist on the surface of each world. While the Earth is friendly to life with oceans of water and ice at poles, Venus resembles something of Hell Dante. While the average surface temperature of the Earth is 14 ° C, the average surface temperature of Venus is 462 ° C. It is 135 degrees warmer than the melting temperature of lead and 43 degrees more than is needed to melt zinc. It is also warmer than your kitchen oven.

Little space for holidays in the solar system.

While it can be expected that Venus will be hotter than Earth, because it is closer to the Sun, it should not be so hot. But when you start looking at the components of the atmosphere, you will begin to understand. Venus has an atmosphere about 90 times denser than Earth's atmosphere. Ninety-six percent of the atmosphere consists of carbon dioxide, a well-known greenhouse gas, and the rest is mainly nitrogen. This means that the atmospheric pressure on Venus is astounding 900 Newtons per square centimeter, around 1300 pounds / square inch. The upper atmosphere of Venus is subjected to very strong winds at speeds of 300 – 400 km / h but there is almost no wind on the surface.

The question is, how did Venus get this atmosphere when the Earth did not?

It is possible that the Earth had large amounts of carbon dioxide, but was absorbed by surface rocks and oceans. Another theory suggests that Venus had an atmosphere like Earth, but extreme volcanic activity flooded the atmosphere with carbon dioxide.

Even without volcanic theory, small differences in atmospheric chemistry can lead to dramatic differences in climate. Venus, being closer to the sun, could have a more pronounced greenhouse effect that would lead to hotter temperatures that pushed carbon dioxide out of the rocks, increasing the greenhouse effect leading to an uncontrolled state where the temperature rose to the present levels.

All this presents a warning for Earth. If such small changes can lead to such dramatic climate changes, we must be very careful in our own world. There are many examples of such small changes in the initial conditions that lead to dramatic changes in the future. This is called the butterfly effect, because the idea that a butterfly flapping its wings in New York could lead to a typhoon in Malaysia in six months. Of course, this is an exaggeration, but it illustrates this point.

We do not understand the climate well enough to be able to predict what change will bring. There are so many variables, and the whole system is sensitive to small changes, which are quite unpredictable, that risking our climate is risky. Our nearest "twin" planet contains a warning that we can ignore at our risk. We have to think about the world that we leave the class 6 and 7 students with whom I talked about the solar system.

Tim Philp enjoyed learning because he was old enough to read. Working all his life in technical fields, he shares his love of learning with readers every week. You can contact him by e-mail to: or by e-mail c / o The Expositor.

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