Jupiter: The Big Bully

The article, “Mars is so small because Jupiter shook up its formation,” explains that Mars may be much smaller than we expect because Jupiter’s gravity beat it up as it was forming. Models of our solar system’s formation suggest Mars should be 1.5 to 2 times Earth’s mass. Instead, it weighs one-tenth the mass of Earth. A theory has resurfaced that gas left over from the formation of Jupiter interfered with the rocks that ultimately created Mars, causing them to fall apart instead of clump together. The gas giants formed by accreting gas from the protoplanetary disc that surrounded the Sun. as they grew, their gravity began to have more of an impact than the remaining disc on the still-forming rocky planets. The disc’s gravity pulled the protoplanets’ axes of rotation in one direction while the gravity from Jupiter tugged them the opposite direction. When those competing forces balance in a certain way, the protoplanets felt a kick from Jupiter’s gravity at the same point in their orbit around the Sun, an effect known as sweeping resonance.

Our objective was to be able to describe the nature of our solar system and how it was formed. This article relates because it discusses the formation of Jupiter and Mars. In the lecture tutorial, “Temperature and Formation of Our Solar System,” we learned that the planets divide clearly into two groups. Jupiter is a jovian planet, along with Saturn, Uranus, and Neptune. Jovian planets are giant gaseous planets similar in overall composition to Jupiter. Mars is a terrestrial planet, along with Mercury, Venus, and Earth. Terrestrial planets are rocky planets similar in overall composition to Earth. According to the tutorial, jovian planets form at temperatures cooler than the freezing point of water and at a distance of 3AU and higher from the Sun. Terrestrial planets form at temperatures hotter than the boiling point of water and at a distance of 0 to 2AU from the Sun. This article also makes reference to a protoplanetary disc surrounding the Sun. We learned in class that it is believed that the solar system formed from the gravitational collapse of a great cloud of gas and dust. Our solar system began with a disk of material surrounding a young star and all the leftover material can form planets. The fact that our solar system began as a spinning disk of gas and dust explains the orderly motions we observe today.

I thought that this was a very informative and interesting article. I liked that the article touched on most of the things that we discussed in class and was not too vague on the topic it was covering. I did not know that another planet’s gravity could affect the formation of another planet. I wonder why this only appeared to happen with Jupiter and Mars and not to any of the other planets in our solar system.


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