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

A Planetary Society Trifecta

A Planetary Society trifecta -- that's what Neil Tyson calls this episode of his StarTalk radio show broadcast this week. His guests include the Society's Vice President, Heidi Hammel, and its Executive Director, Bill Nye, (along with the Society's friend, Steve Squyres, Principal Investigator for the Mars Exploration Rovers).

Eris might be smaller than Pluto after all (but it's still more massive)

Several astronomers pointed their telescope at Eris to watch it pass in front of a background star. Occultations permit precise measurement of the diameters of distant, faint objects, and it turned out that Eris was much smaller than previously thought, so much so that its diameter may turn out to be the same as, or even smaller than, Pluto's.

Hubble turns 20

Tomorrow is the 20th anniversary of the launch of the Hubble Space Telescope. It's hard to believe it's been going strong for so many years.

New maps of Pluto show pretty amazing amounts of surface change

I just posted my writeup of today's press briefing on a new map of Pluto produced from Hubble images. The main conclusion was that Pluto has shown an astonishing amount of changes across its surface between 1994 and 2002 -- more, in fact, than any other solid surface in the solar system.

Ever Plan Ahead? How About Six Years Ahead?

Despite still being more than six years and just over 18 Astronomical Units from the Pluto system, the project team for New Horizons is conducting the second and final portion of our Pluto Encounter Preliminary Design Review (EPDR) tomorrow and the next day.

Frame a Pluto portrait

As New Horizons continues its journey (it's now approaching the orbital distance of Saturn, though it's very far from that planet in space), the mission is taking advantage of the recent experience with the Jupiter flyby to plan out the science operations for the Pluto-Charon encounter.

Yet another active world: Charon

I've just posted a news story on a recently published paper that suggests that Pluto's moon Charon may have active ice volcanoes.

Bedtime for New Horizons

According to the mission website, the New Horizons spacecraft has drifted off to sleep, entering its

New Horizons spots Pluto!

Yesterday the New Horizons team released a flicker animation showing the spacecraft's first sight of Pluto, using the LORRI long-range imaging instrument.

Suggestions for names of Pluto's moons

I received quite a number of emails containing suggested names for Pluto's moons -- thanks! I just sent all the suggestions to Alan Stern; here they are for everybody's enjoyment.

Speaking of Pluto...

I just posted today's installment of Planetary Radio, in which Mat Kaplan gets an update on New Horizons from Principal Investigator Alan Stern-- check it out!

Pluto: The Discovery of a Planet

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

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

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

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.

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