Stories, updates, insights, and original analysis from The Planetary Society.

The Discovery of a Planet, Part 4: Clyde's Search

Since his teenage years Clyde Tombaugh had been an avid amateur astronomer and a gifted telescope builder. Based on instructions contained in an article from a boy’s Sunday school paper, he built a series of telescopes of increasing power and quality on the family farm.

The Discovery of a Planet, Part 3: Planet X

The discovery of Neptune accounted for nearly all the unexplained motions of the outer planets of the Solar System. Nevertheless, several astronomers insisted that some unexplained residual motions remained, pointing to the presence of a ninth planet beyond the orbit of Neptune.

The Discovery of a Planet, Part 2: Out of the Six-Planet World

Since humans first set their eyes to the stars, they noticed that a few of these bright objects behaved differently from the others. Whereas all the stars moved together, revolving around the Earth once every 24 hours, five appeared to move within the firmament among the other stars. Accordingly, they were named “planets,” meaning “wanderers” in Greek.

The Discovery of a Planet, Part 1: The Blinking Image

February 18, 1930, was a cloudy day at the Lowell Observatory, on top of Mars Hill in Flagstaff, Arizona. 22 year old Clyde Tombaugh was hard at work, peering through the lens of an ancient-looking brass-colored device. The instrument, known as a “blink comparator,” mounted two large photographic plates.

Updates from Past Recipients of the Shoemaker NEO Grants (16 April 2004)

2003 was a good year with 50,779 asteroid astrometric observations submitted, including known NEOs and the discovery of a new Aten-class object, 2003 UY12. Based upon the volume of astrometric observations submitted, observatory code 683 was the world's eighth most productive asteroid astrometry station.

Updates from Past Recipients of the Shoemaker NEO Grants (20 March 2001)

I just wanted to express my appreciation again to The Planetary Society for the Shoemaker Grant. Apogee Instruments delivered the AP6Ep purchased with the grant on 9 March 2001. Critical mass on all of the other components associated with implementing the proposal was reached last week.

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