Taking interest in our neighbors has been a habit of humans. This time it is Venus, our nearest neighbor. Venus is the second nearest planet to the sun in our solar system. It is on an average 108 million km away from sun and 72.948 million km away from earth. Venus has been one of the strangest objects in space. Let us know some of the strange facts about it in this article.
Another thing that makes Venus the reason of our interest in it is its similarity to earth. The Venus is almost the same size that of earth – just slightly smaller. We can compare their sizes in this picture.
Like earth, Venus has atmosphere. The atmosphere consists of 96.5% carbon dioxide, 3.5% nitrogen and very small amount of sulfur dioxide and other gases. The temperature in Venus is around 464 deg Celsius. Venus is the hottest planet in the solar system even though mercury is the nearest to sun. This is because of the runaway green house effect, which occurs when a planet's atmosphere contains greenhouse gas in an amount sufficient to block thermal radiation from the planet, preventing the planet from cooling. The greenhouse gas is the gas that absorbs and emits infrared waves (or heat which is an electromagnetic wave). Water vapor, carbon dioxide, methane etc. are the examples of greenhouse gases.
Venus shows phases like moon. As Venus comes closer to earth we see a crescent shape of Venus’s face and when it is farthest from us we see a circular Venus.
The rotation period of Venus is 243 days and revolution period of Venus is 224.7 days. This is interesting because if we were on Venus then one day will be more than a year. Because of this we see a beautiful phenomenon where at the closest approach of Venus and earth, earth always sees the same face of Venus. The exact reason of this is still a topic of research.
The Venus unlike earth rotates in the opposite direction. This means that the sun rises in the west and sets in the east. There have been various theories describing how this might have been caused when all other planets move like earth (move from west to east). In one of the theories it is said that Venus got hit by a large asteroid which reversed its direction. But problem comes when we think of it mathematically. An object which can reverse the direction of Venus can also destroy it because of its speed with which it hit Venus.
So a stronger and reliable theory was developed which says that the flip occurred because of friction between layers of Venus and atmosphere. Let us understand it in some more details. If we cut the earth into half then we can see that the earth is made up of three layers- core (innermost sphere), mantle (middle layer that surrounds core) and crust (outermost layer). Similarly we can see three layers if we cut Venus into two equal halves. These layers move in different speed depending on what material the layers consist of (for example earth’s core mainly contains iron and nickel while mantle mainly consists of oxygen, silicon, magnesium). Yet another theory suggests that Venus might be moving like earth but then it slowly comes to a stop and then moves in opposite direction. While another theory suggest that Venus was smaller than its size that we see now. A bigger object hit the smaller Venus and changed its direction of rotation. But instead of destroying the smaller Venus, the object and smaller Venus came together to form a single planet that we now see as our Venus.
None of these theories are known exact. People are still trying to find the explanation to these mysteries. Do you have any such theory in mind? If yes then do tell. Be curious and keep on learning.
Barnali Das, IISER, Kolkata
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