Pluto was discovered in 1930 by American astronomer Clyde Tombaugh. It was considered the ninth planet from the Sun. In 1992 however, this became a question after several other objects similar in size to Pluto were discovered beyond it’s orbit in what’s known as the Kuiper belt.
The Kuiper belt is similar to the asteroid belt between Mars and Jupiter, but it’s much larger. I’t 20 times wider, and somewhere between 20-200 times more massive.
Although many of the objects in the Kuiper belt are made of rock and metal, most are basically giant dirty snowballs made of methane, ammonia and water.
In January, 2005 a new object was discovered beyond Pluto. It’s called Eris, and it’s 27% more massive than Pluto. It’s 93.6 astronomical units away from the Sun, three times further than Pluto, and placing it in the Kuiper belt.
One astronomical unit is Earth’s distance to the Sun.
Eris was first described as the tenth planet. That’s when astronomers gloves came off, and launched a debate to define what a planet was.
The International Astronomical Union, the internationally recognized authority for assigning designations to celestial bodies made the controversial call.
As of 2006, a planet is an astronomical body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion. that would make it a star. It must have cleared its neighbouring region of planetesimals. Those are planets that haven’t completely formed yet.
This definition effectively demoted Pluto from a planet, to a dwarf planet. It has 5 moons, Charon is the largest, with a diameter just over half that of Pluto. The smaller moons include Styx, Nix, Kerberos, and Hydra. Because Charon is so big, some say it should be called a binary system. This is because Charon isn’t in orbit around Pluto, Both are in orbit around each other, a central point outside each body called the barycenter.
In July 2015, the New Horizons spacecraft became the first spacecraft to fly by Pluto. It sent over 6 Gigs of data back to Earth. The data revealed that Charon`s reddish-brown north polar ice cap is composed of organic macromolecules that may be ingredients for the emergence of life, produced from gases released from Pluto atmosphere and was transferred 19,000 km through space to the orbiting moon.
Pluto is an amazing Planet, yeah, that’s right, planet. The IAU definition of a planet has holes in it. First, a planet must be in orbit around a star. That would discount rogue planets that have left their solar system.
Second, planets must have cleared a path around it’s sun. No planet has done this entirely. Even earth is sharing its orbit with asteroids. Earth doesn’t fit the definition of a planet? That’s just nuts.
This is what Will Grundy of Lowell Observatory in Flagstaff, Arizona argued at the IAU definition of a planet March 21 at the Lunar and Planetary Science Conference in The Woodlands, Texas.
Grundy says a planet is any round object in space that is smaller than a star. By that definition, Pluto is a planet. So is the asteroid-belt object Ceres. So is Earth’s moon. “There’d be about 110 known planets in our solar system,” Grundy says, and plenty of exoplanets and rogue worlds would fit the bill as well.
“People have been using the word correctly all along,” Grundy says. He suggests we stick with the original definition.
Of course we’ll have to convince the astronomy world, and that’s no easy task.
Let’s save Pluto as as the planet it deserves to be.
Thank you for reading.