Inner and outer planets

    Earth is percieved as a rocky planet, what are other planets like? Did you know Mars is cold and that outer planets are really gigantic gas envelopes? What about a liquid planet? Could such a planet exist? And what really defines a planet, anyway? Explore these questions and more on this week’s “SkyTalk.”

    Earth is percieved as a rocky planet, what are other planets like? Did you know Mars is cold and that outer planets are really gigantic gas envelopes? What about a liquid planet? Could such a planet exist? And what really defines a planet, anyway? Explore these questions and more on this week’s “SkyTalk.”
    Credit: NASA and The Hubble Heritage Team (STScl/AURA)

    Listen:
    [audio: st20090413.mp3]

    Visit the Skytalk web page for more information.

    Want a digest of WHYY’s programs, events & stories? Sign up for our weekly newsletter.

    It will take 126,000 members this year for great news and programs to thrive. Help us get to 100% of the goal.