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Pluto: The Discovery of a Planet

Amir Alexander • February 18, 2005

To mark the 75th anniversary of the discovery of the planet Pluto, The Planetary Society presents to its readers the remarkable story of the discovery.

The Discovery of a Planet, Part 6: From Pluto to Sedna

Amir Alexander • February 17, 2005

74 years after Clyde Tombaugh discovered Pluto as a faint dot on a pair of photographic plates, a modern group of astronomers made another remarkable discovery. On March 15, 2004, Michael Brown of Caltech, Chad Trujillo of the Gemini Observatory, and David Rabinowitz of Yale announced the discovery of Sedna – the furthest object ever detected in the Solar System.

The Discovery of a Planet, Part 5: The Aftermath

Amir Alexander • February 16, 2005

The discovery of Planet X was announced to the world on March 13, 1930, which marked the anniversary of William Herschel’s discovery of Uranus in 1781 as well as Percival Lowell’s birthday. The observatory’s communiqué emphasized that the discovery was no coincidence, but the vindication of Lowell’s predictions made years before.

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

Amir Alexander • February 15, 2005

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

Amir Alexander • February 14, 2005

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.

Cassini's Radio Ear on Huygens

Emily Lakdawalla • February 14, 2005

Scientists have released a new sound from Huygens, representing the radio signal that Cassini detected from the little probe as it descended to Titan's surface.

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

Amir Alexander • February 13, 2005

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

Amir Alexander • February 12, 2005

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.

News: Radio Astronomers Rescue Science Results for Huygens' Doppler Wind Experiment

Emily Lakdawalla • February 09, 2005

Earth's radio astronomers have saved the day for one of the Huygens instrument teams. Today, the Doppler Wind Experiment (DWE) team announced their first science results, despite losing nearly all of their expected data.

3-D Views of Titan's Surface from Huygens

Emily Lakdawalla • February 08, 2005

It's been close to a month since Huygens descended to the surface of Titan. Many visitors to this website have expressed impatience with the pace of the release of images from the Huygens cameras, a feeling that is no doubt shared by space enthusiasts around the world who are eager to see refined views of the alien surface of Titan.

They Were the First, and the Last, to Hear from Huygens

Emily Lakdawalla • February 07, 2005

On January 14, 2005, the eyes of the world were on the European Space Operations Centre in Darmstadt, Germany, where Huygens mission operators were anxiously awaiting news from Huygens. Would the little probe -- a mission built in seventeen countries, more than twenty years in the making -- be a success, or would it prove a repeat of the heartbreaking silence of Beagle 2?

astronaut on Phobos
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