Why Pluto Isn’t a Planet, and Why it Was Before

The true story of why Pluto isn’t a planet goes back further than you would think.  It has a lot to do with our understanding of science at the time, and a lot more to do with surprising luck.  I made this video a couple of days ago for the Khan Academy Talent Search.  I hope you enjoy it. It will be interesting as we move into better telescope technologies that allow us to see further into the depths of the solar system and the universe.  What strange mysteries will we find?

Lots of News but Pluto Always Wins

Today is a busy day in the world of astronomy and space news. The US Air Force has approved SpaceX for military launches, ending a ten year monopoly by Boeing and Lockheed-Martin.  A black hole jet moving at nearly the speed of light is having traffic issues, resulting in knots of jet material rear-ending each other. An experiment in Quantum Mechanics has shown that reality simply doesn’t exist until we measure it.  Finally, the Gemini planet imager has found a bright, disk-shaped ring of dust around the star HD 115600, which is being likened to the Kuiper Belt in the...

Hubble’s Best View of a Planetary Disk

At one point in history, let’s say around 1994, astronomers were fairly confident in their understanding of the formation of planetary systems.  Even though at the time we hadn’t found any planets orbiting other stars, they had long been theorized, and we figured that systems would form much like our own solar system.  Rocky planets in the interior, gaseous giants further out, and a huge icy debris field at the outer edges. And then along came 51 Pegasi b.  Half the mass of Jupiter, it orbits its star in only 4 days, far closer than Mercury.  It was considered a...

New Horizons Returns First Pluto Pic!

Being 2015, there has been a lot of talk about the New Horizons spacecraft in the first month of the year, since it’s due to reach it’s rendezvous with the enigmatic dwarf planet in July.  I remember watching the launch in 2006 while in university, and have been talking about it to audiences during my planetarium shows.  I feel close to the mission, and being able to see it reach Pluto this year brings back the first feelings I ever had about discovering the universe as a child. So when the spacecraft woke up a few weeks ago, so did...