Pluto  Five Facts About The Little Planet
Channel: ahad 1s
Date: 2015-07-21

Now that NASA has caught up with Pluto through its New Horizons spacecraft, scientists will be looking to find out more about the dwarf planet.
Pluto is a dwarf planet, which means, by the 2006 definition, it does not fulfil all of the conditions needed to be a "full-blown" planet.

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New Horizons Principal Investigator Alan Stern, Johns Hopkins University Applied Physics Laboratory Director Ralph Semmel, and New Horizons Co-Investigator Will Grundy Lowell Observatory.
images of mission control in Maryland
Gallery: Success For Nine-Year Mission To Pluto - And Beyond
images of mission control in Maryland
images of mission control in Maryland
images of mission control in Maryland
New Horizons Principal Investigator Alan Stern, Johns Hopkins University Applied Physics Laboratory Director Ralph Semmel, and New Horizons Co-Investigator Will Grundy Lowell Observatory.
images of mission control in Maryland
Gallery: Success For Nine-Year Mission To Pluto - And Beyond

It was downgraded from planetary status in the IAU edict because it was considered too small to attract all the space dust and tiny objects in its path and therefore did not comply with the third category as defined above. Also, it is not a moon.

Indirectly, Pluto was the reason the IAU brought in its definitive ruling on planets. US astronomer Mike Brown found a new object behind Pluto and, thinking it was another planet, he named it Eris.

That new discovery led to astronomers discussing what made a planet and the IAU decided Pluto and similar objects were too small and wrongly situated to be planets. Therefore they reclassified them.

3. WHEN WAS PLUTO FOUND?

The planet was discovered by US astronomer Clyde Tombaugh on 18 February, 1930, and was the ninth planet to be identified. It is much smaller than other planets such as Mercury, Mars or Earth and it shares its orbit with Charon, which is nearly half its size again.


Play video "Pluto Flypast 'Hallmark' In History"

Video: Pluto Flypast 'Hallmark' In History
Until this latest exploration little was known about Pluto and scientists are hoping the data transmitted by the spacecraft will dramatically increase their knowledge. The spacecraft that has been orbiting the outer reaches of her solar system is carrying some of the ashes of the scientist, which means that Mr Tombaugh has finally reached Pluto.

4. WHY IS IT CALLED PLUTO?

Pluto was given its name by Venetia Phair, an 11-year-old British girl who, a month after its discovery, suggested to her mother and grandfather the planet should be named after the Roman god of the underworld.

Venetia's grandfather had been head of Oxford University's Bodleian Library and he had friends in high places.

He sent a letter to Professor Herbert Hall Turner, who had once been the Astronomer Royal suggesting the name. Professor Turner in turn cabled the American astronomers at the Lowell Observatory who were wondering what to call the new planet.


Play video "What Do We Now Know About Pluto?"

Video: What Do We Now Know About Pluto?
They liked the name and, in May 1930, Pluto got its name.

5. WHAT'S PLUTO ALL ABOUT?

Pluto is so cold that scientists use the Kelvin scale to measure it. On that scale, the average temperature is 375 to 400 degrees below zero and the surface is likely to be covered with frost and ice. The dwarf planet has about one-fifteenth the gravity of Earth, so a person who weights 100lbs on Earth would weight about 7lbs on Pluto.

Pluto is about 39.5 astronomical units (AU) from the Sun, making it almost 40 times further away than Earth. It takes 248 years for Pluto to make one revolution around the Sun and more than six days to rotate. That means one day on Pluto is the equivalent to about six-and-a-half days on Earth.

It is about 1,400 miles wide, around half the width of the US.