Question

Read the article “Then, Now, and Future: Extra Solar Planets” on p. 283 of your textbook. Briefly summarize a method for finding extrasolar planets referencing Newton’s Universal Law of Gravitation and Newton’s Third Law, then explain why it is unlikely that planets found using this method would support life (as we know it.)

Answer 1

According to Newton's law of gravitation, the force between two mass objects is given as:

Where is the gravitational constant, is mass of first object, is mass of second object, is the distance between objects masses.

When star is about to born in the newly solar system, the gas clouds from surrounding nebula and dust start to clump together due to gravitational force according to Newton's law of gravitation. Since gas and dust are acting force on each other, they come into motion. Since the center of this clump is acted as a center gravity, all the gas and dust come into rotational motion which is known as accretion disk of protostar. This process continues until the temperature reaches high enough to spark the nuclear fusion and be formed the star.

Once star is born, dust and gas are born still in rotational motion around star in the entire solar system. The leftover gas and dust forms planets and that how the solar system further evolves always in rotational motion.

Now, according to law of conservation for linear and angular momentum until external force is not applied, the angular momentum is conserved. Therefore, the motion started when protostar is formed is conserved and all the dust star form planets is in rotational motion.

In the case of planetary motion, it is always presumed that planet is orbiting around the host star but scientifically that is partial truth. In reality, the host star and planet both orbit around each other a common point of center of gravity. According to law Newton's third law, the wobbling effect is generated in star due to one of the biggest planets (highest mass) in the solar system. Since more than 99% mass is occupied by host star, the wobbling in the motion of star due rotation around common center of gravity is minor and generated by the highest mass planet in the solar system.

This distance observation of wobbling effect in star is possible from the Earth. Therefore, whenever extra solar planet is discovered in the distance solar system through the method of wobbling observation, it must be biggest extra solar planet in that solar system. From the study of evolution of our own solar system, we know that massive planets are gas giants. And for this reason, it is assumed that extra solar planets discovered from the wobbling effect are gas giants and cannot harbour life on it.