March 24 – To Hades With You!

Today’s factismal: It would take 5.6 planets the size of Pluto to make one Moon (and 169 to make one Earth).

In just under 90 days, we will make a dream come true. For the first time, we will have visited every “traditional planet” with a probe. Back in 1964, planetologists noticed that the planets would be in the perfect positions to visit them all in a “Grand Tour” with four probes. Two would would be launched in 1976 and 1977 and fly by Jupiter and Saturn before heading out to Pluto. Another two would be launched in 1978 and would fly by Jupiter, Uranus, and Neptune. At each planet the probes would swing in close and use the slingshot effect to throw them out to the next planet. But that dream died thanks to tight budgets and a lack of public interest.

Or rather, it almost died. The planetologists salvaged the idea and changed the Grand Tour into a Greatest Hits voyage to Jupiter, Saturn, Uranus, and Neptune in what became known as the Voyager Program. These were the last of the great exploration probes; after they passed by Neptune, NASA turned its attention to Mars and Venus which were much closer and cheaper to visit. With a regretful wave, the planetologists settled for studying Pluto via telescope. And they discovered some amazing things.

A plot of planetary size versus density. Notice how Pluto ends up with the junk.

A plot of planetary size versus density. Notice how Pluto ends up with the junk.

Pluto and her five moons (Image courtesy NASA)

Pluto and her five moons
(Image courtesy NASA)

The first thing that they discovered was that instead of being as large as the other outer planets, Pluto was just a tiny thing. With every new measurement, Pluto shrank from being as big as Jupiter (a thousand times as massive as Earth) to being the size of Earth to being so small that it would take five of them to equal the Moon’s mass. Excitingly, they also discovered that Pluto two distinct hemispheres with one side of the planet being much brighter than the other. They also found that Pluto has five moons of its own (the most recent pair being discovered in 2011 and 2012). And with each new discovery, our regret at not visiting this fascinating planet grew.

 

The New Horizons spacecraft will meet Pluto in two years (Image courtesy NASA)

The New Horizons spacecraft will meet Pluto in two years
(Image courtesy NASA)

The moons of Pluto (Image courtesy NASA)

New Horizons’ path to the stars by way of Pluto
(Image courtesy NASA)

And it grew until finally NASA agreed to send a small probe rocketing past the planet. Originally called the Pluto Express (both for how fast it will go past the planet and for how quickly it was built), the probe is now known as the New Horizons. Launched nine years ago, the probe will reach Pluto in about 90 days. But the probe will be going so fast that it can’t stay to image the planet; instead, it will speed past and head on out to the outer parts of the Solar System.

And that’s where the citizen science starts! Because the data will be coming in hot and heavy during the few days when the probe is close enough to get a good view of the planet and its moons, the scientists are lining up the names for those things now – and they want your help! They have set up a web form for us to vote on various names for Pluto’s features and to propose names of our own. Of course, even if a name is popular, that’s no guarantee that it will be used; the IAU (the folks who don’t know what a planet is) overruled the name picked by the discoverer of Pluto’s fifth Moon (Vulcan) for one of their own (Kerberos).  But it will still be fun to name the features and learn more about this amazing planet as New Horizons makes a fifty-year old dream come true in three months. For more information, zoom on over to:
http://www.ourpluto.org/vote

3 thoughts on “March 24 – To Hades With You!

  1. Pingback: June 5 – How High The Moons | Little facts about science

  2. Pingback: Bonus Factismal – Colder Than Hades | Little facts about science

  3. Pingback: July 14 – Calling All Planets | Little facts about science

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