Astronomy: Venus

Thanks for visiting our blog! If you want to support education youth across the globe, please donate here or share to your friends. Enjoy!

Table of Contents

  1. Basic Facts
  2. Surface Composition
  3. Atmosphere
  4. For Educators

Venus: The Facts

Venus is the second of the four terrestrial planets with regard to distance from the sun. This distance is about 67 million miles, so about 70 percent of Earth’s(which is 93 million miles). The mass of Venus is 4.9*10^24 kilograms. An interesting thing about Venus’s orbit is that it is retrograde in comparison to Earth’s. This simply means that Venus rotates in the opposite direction that Earth does(rotation is the spin of the planet, revolution is the orbit around the Sun). Somethings can appear to move in retrograde across the sky, such as other planets like Jupiter, because of the way our orbits work. When the Earth starts passing Jupiter, for example, it looks like the planet is going backwards in the sky(West to East), even though both Earth and Jupiter orbit the Sun in the same direction. This is called apparent retrograde motion and is caused simply by Earth passing Jupiter, and once it passes, Jupiter appears to move forward again. Anyhow, Venus is believed to have a molten core, not solid, because of the small mass of the planet. It likely does not exert enough pressure to be totally solid, just like Mercury. What makes Venus special is just how hot it gets. Venus has the thickest atmosphere out of all the planets, and it is mostly carbon dioxide. You likely already know that carbon dioxide traps heat; it is a greenhouse gas. In small quantities on Earth, we see temperatures rise. However it makes up less than one percent of the atmosphere. In Venus, 97 percent of the atmosphere is nothing but this gas! Thus, even though Mercury is closer to the Sun, Venus is the hottest planet, and it has a relatively stable temperature. This can go up to 880 degrees Fahrenheit!

Surface of Venus

Venus has a rocky surface like Earth, and also has mountains, craters, and volcanoes. It also has very long lava channels, the longest is called Baltis Vallis and is 6800 kilometers long. Volcanoes on Venus are generally shield volcanoes, which are very wide volcanoes but are short. The largest volcano is Maat Mons. The most notable fact about Venus’s Surface is that although it has craters, these are sparse and overall the surface is very smooth. These large, and smooth, regions are called basaltic plains, because the smooth rock is basalt. This type of rock is formed by the slow cooling of lava. Remember how volcanoes are very abundant, so every time a volcano erupts massive amounts of lava flows out of these shield volcanoes. This lava spreads over the surface of the planet and very slowly cools(the surface can reach 880 Fahreinheit so this “cooling”, which is solidification of the lava. takes an extremely long time). Since it cools so slowly, it becomes very smooth and thus forms these smooth plains, rather than being rugged and bumpy. Over time, you may expect this surface to get rugged with craters from asteroids, but it is not so. This is best explained by the lava cooling being very recent(past couple million years), so not much has been able to impact it, along with this new surface covering up all the old craters.

This is a picture of Maat Mons, the largest volcano on Venus

The Very Thick Atmosphere Of Venus

Venus has a very thick atmosphere, with the pressure from the atmosphere being 90 times that of Earth’s! That would be the pressure 900 meters deep underwater(this could crush many things). The atmosphere is mainly(96%) carbon dioxide, or CO₂, gas, which allows for it to trap heat in very well. This massive amount of this gas accounts for why Venus is so hot. The rest of the atmosphere is mainly nitrogen gas(3%). In the remaining 1%, a unique occurrence of sulfuric acid occurs. Since Venus is so hot, the sulfuric acid is evaporated and forms clouds. Specifically, this happens because of the interaction of SO₂ and H₂O(sulfur dioxide and water), which forms this acid. Acid rain on Earth happens the same way, but since this acid is not common at all(the acid rain on Earth is because of pollutants), we do not see clouds of it happen. On Venus, the sulfuric acid is more common so it is able to vaporize and form clouds.

For Educators

Every post I do was intended to have a for educators section, but when it comes to an individual planet, I do not think it is necessary. Each planet should only be discussed briefly, when teaching astronomy, its more important to give the big picture and get people attracted to astronomy. As such, I am going to skip this section for most of the planets. I think a short talk about each planet is sufficient. If you have anything you’d like in this section, please let me know.

Thank you

Thank you for reading! Any questions feel free to contact me at vijaypbharti01@gmail.com!

Astronomy: Mercury

Thanks for visiting our blog! If you want to support education youth across the globe, please donate here or share to your friends. Enjoy!

Picture of Mercury. Color enhanced beyond visible light to show variations we can’t see

Table of Contents

  1. Basic Facts
  2. Layers of Mercury
  3. Surface Composition
  4. Atmosphere?
  5. For Educators

Basic Facts of Mercury

Mercury orbits at 38 thousand kilometers from the Sun and weighs 3.285 × 10^23 kg, which is about a tenth of the weight of Earth. It orbits the sun once every 88 days(We orbit the Sun once every 365 days, which constitutes a year). Mercury has the most elliptical orbit out of all the planets. Planets do not orbit the Sun in a circle, but rather as an ellipse(an oval) which is explained by Kepler’s Laws. The year to day ratio of mercury is 2/1. This means that one day on Mercury is 2 years on Mercury! That sounds awfully confusing but to understand, the year to day ratio of Earth is 1/365. This means each year, 365 days occur. A day of a planet is how long it takes for the planet to turn one full rotation(360 degree). A year of a planet is how long it takes for the planet to make one revolution around the Sun. Thus, this means that Mercury orbits the Sun twice before it finishes one rotation around itself. This is because Mercury is really close to the Sun, so it can orbit around the Sun very fast. It also rotates around itself very slowly, which helps account for the odd ratio I provided. Finally, in terms of Earth days, Mercury orbits around the Sun every 88 days and rotates around itself every 176 days(thus the 2 to 1 ratio).

Layers of Mercury

Mercury, being a terrestrial planet, is dense. This is accounted for by the inner most layer of Mercury, the inner core, which is solid iron. The pressure from the rest of the planet(basically the weight of all this iron and the stuff on top of it) accounts for the solid behavior. After this comes a liquid outer core of similar composition. Then comes the mantle, which is separated from the outer core by a layer of solid iron. Explaining this is difficult, and I am not entirely sure why such a layer exists. Generally with less pressure comes a liquid form, and I have not come across explanations for this. The mantle of mercury is made of silicates(compounds made of silicon and oxygen) and is very thin, only 500 kilometers. Finally is the crust, which is considered the surface of mercury. This is discussed next.

Comparison of Earth’s interior to Mercury. Mercury is very small compared to Earth(about a tenth in mass) and has a significantly different interior).

Surface of Mercury

Mercury has a unique surface, but a great way to think of it is similar to the moon. There are many craters caused by impacts from different space objects like debris, asteroids, and planetesimals. The largest crater on mercury is Coloris Basin. The cracks of the smooth regions of mercury, rupes, are long cracks on the older surface of mercury caused by faults on Mercury(like fault lines on Earth where earthquakes happen). Final thing to know is the temperature changes of Mercury. As I will talk about next, Mercury does not have an atmosphere. Thus, temperature changes are extreme. It ranges between -300 to 800 degree Fahrenheit based on if it is day or night! Note that by extreme I mean the range of the temperatures, the change in temperature is not constantly fluctuating as the planet spins very slowly. It gradually decreases as night approaches.

The line through the middle is one of the rupes we discussed above. It is formed by a thrust fault(a fault like that of where an earthquake occurs).

Mercury’s Questionable Atmosphere

It is easiest to say that Mercury has no atmosphere. An atmosphere is the gases held by gravitation of a planet. Because of Mercury being so light, it does not have the mass to hold an atmosphere. Another issue is that Mercury is too close to the Sun. Remember the phenomena we talked about with the Sun? Those phenomena and just the flow of charged particles out of the sun produces what is called a solar wind. This wind blows away most of the “atmosphere” that the planet could hold onto. This means there is essentially nothing to consider as an atmosphere. However, there is still a little bit of gas held by the planet. This is mainly oxygen, sodium, and hydrogen. For reference, it is 10^34 times sparse than Earth’s atmosphere. That is Earth’s atmosphere divided by 1 with 34 zeroes in front of it.

For Educators

Every post I do was intended to have a for educators section, but when it comes to an individual planet, I do not think it is necessary. Each planet should only be discussed briefly, when teaching astronomy, its more important to give the big picture and get people attracted to astronomy. As such, I am going to skip this section for most of the planets. I think a short talk about each planet is sufficient. If you have anything you’d like in this section, please let me know.

Thank you

Thank you for reading! Any questions feel free to contact me at vijaypbharti01@gmail.com!