Season 1
Episode 1
Airdate October 24, 1999
Curriculum Science

Pluto is a BrainPOP Science video that launched on October 24, 1999.

This episode was the very first BrainPop episode.



Transcript and QuizEdit

FYI Edit

Real Life Edit

From its discovery in 1930 until 2006, Pluto was considered to be a planet. Here’s the story of why its status changed!

When Pluto was discovered by Clyde Tombaugh in 1930, it was significantly larger than anything known to be near it in the solar system. So at the time, it made sense to consider it a planet.

Then in 1992, with the benefit of much better technology, astronomers discovered the Kuiper Belt, an area of rocks, asteroids, and other space debris located just beyond Neptune. And some of the objects in the newly-discovered Kuiper Belt made Pluto seem a lot less special.

For instance, a body named Quoar, discovered in 2002, was about half as large as Pluto, and Sedna, discovered in 2004, was only a few hundred kilometers smaller than the planet. Finally, in 2005, Eris, which was larger than Pluto, was discovered.

Some of these objects had moons, and some had atmospheres. It was starting to seem like Pluto was just one of many small bodies floating out there in the Kuiper Belt.

The controversy came to a head in 2006, when the International Astronomical Union voted to create the new category of dwarf planets. They put Pluto into it, along with Eris and Ceres, the largest body in the asteroid belt (two more dwarf planets were added in 2008). This didn’t please everyone, though; a number of astronomers maintain that Pluto should still be considered a planet.

Graphs, Stats, and Numbers Edit

Here are some facts about Pluto!

Orbital period: 248.09 Earth years.

Number of known moons: 5.

Minimum surface temperature: 33 K.

Maximum surface temperature: 44 K.

Composition: Nitrogen and methane.

Average radius: 1,195 km, 19 percent of Earth’s radius.

Surface gravity: 5.9 percent of Earth’s gravity.

Surface area: 1.795 x 10^7 square km, 3.3 percent of Earth’s surface area.

Volume: 7.5 x 10^9 square km, 0.66 percent of Earth’s volume.

Mass: 1.3 x 10^22 kg, 0.21 percent of Earth’s mass.

Discoveries and Inventions Edit

Pluto was discovered in much the same way as Neptune: During the late 19th century, studies of Neptune’s orbit suggested that there might be another planet somewhere nearby.

The search to find the new planet began in 1905 by a man named Percival Lowell. A member of a wealthy and prominent Boston family, Lowell had funded and set up the Lowell Observatory in Flagstaff, AZ.

He spent the last 11 years of his life looking for the new planet. According to one of his associates, his disappointment at never finding the new planet “virtually killed him.”

For the next 10 years after his death, work on locating the new planet — which Lowell had dubbed “Planet X” — was halted due to a dispute over money that Lowell had donated to his observatory in his will.

Then, in 1929, the Lowell Observatory’s director, Vesto Slipher, handed the task of trying to locate the new planet to a 22-year-old farmboy from Kansas named Clyde Tombaugh (pictured).

On February 18, 1930, Tombaugh examined a series of images that had been taken of the same patch of sky over the course of several nights, looking for any object that might have moved. He found one — and it was Pluto.

Trivia Edit

Shortly after Pluto was discovered, its name was suggested by an 11-year-old British schoolgirl named Venetia Burney (pictured). The other two candidates for the name were “Minerva” and “Cronus.”

The Disney animated character Pluto, who made his first appearance in 1930, was named after the celestial body. So was the element plutonium, which was named in 1941.

Pluto is smaller than Earth’s moon; it’s also smaller than four of Jupiter’s moons, one of Saturn’s, and Neptune’s moon Triton.

Pluto has four moons in addition to Charon: Nix, Styx, Hydra, and Kerberos. In Greek mythology, Nyx is the goddess of darkness and night (as well as Charon’s mother); Styx is the river that runs through the underworld; Hydra and Kerberos are monsters that guard the gates to the underworld.

Some of the ashes of Clyde Tombaugh, the astronomer who discovered Pluto, have been placed on board New Horizons, a NASA craft that will approach Pluto in 2015.

In 2006, 54 members of the California State House of Representatives introduced a measure condemning the International Astronomical Union for demoting Pluto. The resolution claimed that Pluto’s demotion would “cause psychological harm to some Californians who question their place in the universe.”

The verb “to pluto” has recently entered the English language. According to the American Dialect Society, which named it the 2006 Word of the Year, to pluto something is to “demote or devalue” it.

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