Astronomers believed that the Solar system has nine planets.
For decades, astronomers thought we had nine planets in the Solar system. However, in 2006 Pluto lost its status as a planet. Now, famous astronomers Alan Stern and David Grinspoon want to give Pluto back its title. They wrote their findings in the Washington Post, where they talk about the New Horizons probe sent to Pluto.
The decision of stripping Pluto of its status was taken by a small group of astronomers – the International Astronomical Union (IAU) that met in 2006 in Prague.
Astronomers Stern and Grinspoon believe that the “decision was flawed and that a logical and useful definition of planet will include many more worlds.”
“Two Thrilling Discoveries About Our Universe”
The astronomers have made two discoveries about the universe, which made them reconsider the term “planet”:
“There are planets in unbelievable abundance beyond our solar system – called “exoplanets” – orbiting nearly every star we see in the sky. And there are a great many small icy objects orbiting our sun out in Pluto’s realm, beyond the zone of the rocky inner worlds or “terrestrial planets” (such as Earth), the “gas giants” (such as Jupiter) and the “ice giants” (such as Neptune),” explain Stern and Grinspoon in their article.
Looking at the discoveries, we should ask ourselves what are we going to call space objects orbiting other stars. Which are planets and which aren’t? So, if our sun is a small star – a “dwarf star,” then should we consider Pluto a “dwarf planet”?
Finding a Better Definition of Planets
The authors argue that redefining a planet was a mistake that many have criticized:
“For one thing, it defines a planet as an object orbiting around our sun – thereby disqualifying the planets around other stars, ignoring the exoplanet revolution, and decreeing that essentially all the planets in the universe are not, in fact, planets.”
In March 2017, at the annual Lunar and Planetary Science Conference, scientists shared new ideas and results. One presentation wanted to make things right. The presentation “A Geophysical Planet Definition” stated that the word “planet” should have a better definition. It must emphasize its “intrinsic physical properties over its extrinsic orbital properties.”
So, the definition of a planet is quite simple:
“A simple paraphrase of our planet definition – especially suitable for elementary school students – could be, ’round objects in space that are smaller than stars.’”
Bottom line, Pluto is a round object in space, smaller than a star, so it is a planet!
Andre Blair s is the lead editor for Advocator.ca. He holds a B.A. in Psychology from the University of Toronto, and a Master of Science in Public Health (M.S.P.H.) from the School of Public Health, Department of Health Administration, at the University of North Carolina at Chapel Hill. Andre specializes in environmental health, but writes on a variety of issues.