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Planetary RadioDecember 29, 2015

2015: A Great Year for Space Exploration

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On This Episode
Jason Davis thumbnail
Jason Davis

Editorial Director, The Planetary Society

Casey Profile Picture Thumbnail
Casey Dreier

Chief Advocate & Senior Space Policy Adviser, The Planetary Society

Emily Lakdawalla 2017 headshot square serene
Emily Lakdawalla

Solar System Specialist, The Planetary Society

Our year-end review features the “best of 2015” lists from Jason Davis, Casey Dreier, Emily Lakdawalla and Bill Nye the Science Guy. What’s Up offers planets, a comet, and a nice prize package for the space trivia contest.

Space highlights of 2015

Ceres: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA / Daniel Macháček; Falcon 9: SpaceX; Comet 67P: ESA / Rosetta / NavCam; LightSail: Josh Spradling / The Planetary Society; Pluto: NASA / JHUAPL / SwRI / ZLDoyle; Mosaic: Tanya Harrison / The Planetary Society

Space highlights of 2015
From left to right: 1. Dawn's view of dwarf planet Ceres and its now less mysterious "bright spots," found to likely be composed of salts. 2. SpaceX returned its Falcon 9 rocket to flight with flair, successfully deploying 11 communications satellites after returning the rocket's first stage to Cape Canaveral for an upright landing. 3. Comet 67P/Churyumov–Gerasimenko shows off its dramatic jets for the Rosetta mission, which is still actively monitoring this small but active body. 4. The Planetary Society's LightSail had a successful test flight earlier this year. 5. New Horizons stole the show in 2015 by returning stunning images of Pluto, revealing a beautiful and geologically complex world to human eyes for the first time.

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Trivia Contest

This week's prizes are a lovely Planetary Radio t-shirt, a 200-point astronomy account AND a set of Year In Space wall and desk calendars.

This week's question:

What is the orbital period (length of a year) for Sedna, the far distant object in a highly-elliptical orbit?

To submit your answer:

Complete the contest entry form at or write to us at no later than Tuesday, January 5th at 8am Pacific Time. Be sure to include your name and mailing address.

Last week's question:

What Apollo spacecraft was name Falcon? Give us the mission number and type of spacecraft.


The answer will be revealed next week.

Question from the week before:

What are the four worlds in our solar system that sand dunes have been discovered on?


The four worlds in our solar system known to have dunes are Venus, Earth, Mars and Titan. Arrakis and Jakku are not in our solar system.

Listen more: Enceladus, Planetary Society Projects, Dawn, Saturn's moons, Jupiter's moons, Europa, Pluto, Orion, Charon, FY2016 NASA Budget, Planetary Radio, LightSail, Mars, Planetary Society, Bill Nye, InSight, Cassini, Curiosity (Mars Science Laboratory), asteroid 1 Ceres, rockets, Commercial spaceflight, Rosetta and Philae, Humans to Mars, Space Launch System, asteroids, human spaceflight, International Space Station

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