Little Bits of History

February 18

Posted in History by patriciahysell on February 18, 2017

1930: Pluto is discovered by Clyde Tombaugh. Tombaugh was born in 1906 in Illinois and the family moved to Kansas when he was a teenager. A hailstorm destroyed their crops, ending Clyde’s hopes for a college education. Instead, he began to build his own telescopes at home. He hand dug a pit 24 feet long and 8 feet deep, measuring 7 feet wide in which to lower his scopes to create a better environment for watching the night sky. In a temperature controlled pit free of air currents he was able to make several observations. He sent detailed drawing of Jupiter and Mars to Lowell Observatory and they offered him a job. He worked there from 1929 to 1945.

His job at the Flagstaff, Arizona observatory was to make a systematic search for a proposed trans-Neptune planet theorized by Percival Lowell and William Pickering. Tombaugh used the 13-inch astrograph (a telescope designed solely for taking pictures of space) to observe the same section of the sky several nights apart. He then used a machine to compare the sequential photographs to determine if there were any objects moving through the background stability of the night stars. He noticed such an object. He had already found many asteroids and was able to determine, due to the orbit outside Neptune, what he had discovered was the mathematically predicted planet Lowell and Pickering had hoped for. Images from January were studies and on this day, the discovery was made.

There were several names suggested for the new planet (since demoted to dwarf planet) but Venetia Burney (11-year-old schoolgirl from England) suggested the Roman god of the underworld who could make himself invisible. Due to the far flung orbit and hidden nature of the find, Pluto became the name for the first of many objects found in Kuiper belt, sometimes referred to as the “third zone” of the solar system. The Kuiper belt is disc shaped like the asteroid belt between Mars and Jupiter and not to be confused with the Oort cloud which is spherical and surrounds the entire solar system in every direction.

Pluto is the second most massive object in the Kuiper belt, Eris being larger but far more distant. Pluto’s orbit is quite eccentric, ranging from 30 to 49 astronomical units from the sun, a difference of 3 billion kilometers from closest to farthest point. Pluto has five known moons with Charon being the largest. As our observational equipment grew ever more powerful, many more objects were discovered outside Neptune’s orbit. As more of these bodies were found, it became necessary to reassess our definition of what a planet actually was. In 2006, a consensus was agreed upon and Pluto did not meet the requirements. Therefore, it was reassigned as a dwarf planet.

I refuse to accept Pluto’s resignation as a planet. – Amy Lee

With any luck, by the time NASA’s space probe hits Pluto, you’ll be booking a spaceflight with a privately run suborbital airline. – Burt Rutan

When I was a little kid, we only knew about our nine planets. Since then, we’ve downgraded Pluto but have discovered that other solar systems and stars are common. So life is probably quite prevalent. – Buzz Aldrin

Pluto’s orbit is so elongated that it crosses the orbit of another planet. Now that’s… you’ve got no business doing that if you want to call yourself a planet. Come on, now! There’s something especially transgressive about that. – Neil deGrasse Tyson


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