When people say Pluto isn’t a planet, they often say it is an icy body and therefore it must be a comet, not a planet. But are icy worlds simply comets? Or can real planets be made of ice? And what is the difference between ice and rock, anyway? Let’s…
Category: Planetary Science
Planet Tossing and the Kuiper Belt
To get ready for the New Horizons flyby of Pluto (this July!), I’m writing a series on the science of Pluto and the Kuiper Belt. Here is the next installment. There are some very strong hints that the planets haven’t stayed in their original orbits and the giant planets tossed…
The Dance of the Kuiper Belt
The Pluto flyby is a once-in-a-lifetime event, so to get ready I’m writing a series on the Kuiper Belt. This time we’ll look at how solar system bodies are classified by the way they dance. Orbital Resonance The planets’ orbits are affected by something called resonance. When you were a child…
Planetary Science
Measuring Planets Like Sand
About 2300 years ago, a human being measured the world. It was Eratosthenes, the Greek scholar. Imagine how he felt when he first realized what he had done. “Wow, I am the only person who has ever known the size of the world.” It must have been amazing. And humbling….
Kuiper Belt
The Kuiper Belt Awards
Note: this post (with the previous one) is intended to illustrate how BIG our solar system is by reviewing all the named bodies beyond Neptune. When Pluto was reclassified as ‘not-a-planet’ then people interpreted it to mean the important stuff ends at Neptune. Sadly, most people don’t know about all…
Kuiper Belt
Underworld Party in the Kuiper Belt
In July, New Horizons will become the first spacecraft to explore the third zone of the solar system. It’s time we familiarize ourselves with this region of our home star! We know the classical planets’ names and their meanings, but what about the hundreds of newly discovered dwarf planets and…
Planetary Science
Nine Reasons Why Pluto Is a Planet
As the New Horizons spacecraft approaches the amazing Pluto system for an historic flyby in July, 2015, it’s inevitable we should discuss whether Pluto is a proper planet or only a “dwarf planet” as the International Astronomical Union (IAU) voted in 2006. The IAU’s definition of a planet says that…
Planetary Science
Planet Pluto!
What We’re Missing in an Eight Planet Solar System I agree with those who say Pluto should be classified as a planet. Please let me explain why. The Purpose of Scientific Definitions Why do scientists classify things and define terminology? To promote science. We think more clearly when we sort…