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Our Solar System May Be Stranger than We Thought

July 15, 2020

By Vanessa Shell, age 15

by Vanessa Shell, age 15

Lauren Weiss, a Parrent Postdoctoral Research Fellow at the Institute for Astronomy at the University of Hawai’i, Manoa, encountered an interesting pattern among the planetary systems newly discovered by the Kepler spacecraft. But, our solar system does not adhere to the pattern she discovered. Weiss’ research raised the question of whether our group of planets is an outlier, or whether her discoveries were simply based on coincidences.

The Kepler — named after the 17th-century German astronomer — is a NASA spacecraft that launched in 2009 with the singular purpose of finding new planets in our universe. Since then, over 400 multi-planet systems have been found. The Kepler has spotted these other solar systems by way of continuously measuring the brightness of other stars and waiting for the light coming from the star to dim slightly, which signifies a planet passing in transit. Using Kepler’s findings, Weiss was found that planets in the same system tended to be the same size. Giving an example, she said, “If one planet is 1.5 times the radius of Earth, the other planets in the system are very likely to be 1.5 times the radius of Earth, plus or minus a little bit.”

The whole population of exoplanets discovered ranges from one-fourth of the size of Earth to twenty times the size of our planet. With this in mind, Weiss stated, “Despite the wide range of possible sizes, planets tend to be the size of their neighbors.” These solar systems with like-sized planets were soon dubbed “peas in a pod” by the group studying them. Weiss decided then to develop an experiment to test the “peas in a pod” theory, asking the question, “Could some sort of bias in Kepler’s method of finding planets—which favors the detection of large planets close to their stars — contrive to make the planets in each of my imaginary systems appear to fit the pattern?”

The answer to this question seems to be no. In more than 1000 different trials with randomly assigned planet sizes put through a virtual version of Kepler’s detection program, a pattern of like-sized planets in the same systems never emerged. Weiss concluded that the computational experiment did not reproduce what was being observed in the Kepler planetary systems.

The conclusion, for now, seems to be that planetary systems in the universe favor planets of the same size. Our own solar system has radically different size planets, making it very strange by comparison.

Weiss’s research leads us to question the efficacy of existing technology in the scientific study of space. Perhaps we are limited by the technological abilities of the Kepler telescope when it comes to discovering planets in faraway systems. As technology continues to evolve, humankind must develop a more effective and efficient way to determine the size of planets in faraway systems.

[Sources: Scientific American: NASA]

About the Author:
Vanessa Shell is a junior at West High School and has been working at Simpson Street Free Press for almost two years.  She is interested in writing articles about space science and social justice.  In her free time, Vanessa enjoys reading and spending time with her family.

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