Solar System

One would assume that a generation that grew up in the age of the internet would be flexible and able to adapt to the changes in our world. One would be terribly wrong. From a new Companion on Doctor Who to getting rid of the penny, our generation seems hobbled by nostalgia. The same nostalgia that makes sure Michael Bay has a career.

Go find yourself someone between the ages of 20 and 35 and ask them their opinion on Pluto. You’ll get an earful of sadness for its “Demotion” from a planet.

So What Happened?

Pluto was discovered back in 1930. At the time it was the only other planetary body, after the first 8, we could find. Telescopes improved and we eventually found new objects that looked and acted like Pluto. We even found that some of the objects we thought were asteroids in the asteroid belt looked and acted like Pluto.

In 2006 the International Astronomical Union (IAU) needed to figure out what constituted a planet. They had 3 possible “new planets” (Eris, Charon, and Ceres) and weren’t sure what to do.

They drafted a proposal for what a planet was and it would have seen our solar system have 12-24 planets, in the short term.

Here’s what they defined as a planet in the first draft: “A planet is a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet.”

Astronomers estimated that as we observed more of our solar system we’d find that there are over 200 astronomical bodies that fit this description.

The definition went through several drafts and they finally decided on the following as a definition:

The IAU…resolves that planets and other bodies, except satellites, in the Solar System be defined into three distinct categories in the following way:

(1) A planet [1] is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

(2) A “dwarf planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape [2], (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.

(3) All other objects [3], except satellites, orbiting the Sun shall be referred to collectively as “Small Solar System Bodies”.[note 1]

Footnotes:

[1] The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

[2] An IAU process will be established to assign borderline objects into either dwarf planet and other categories.

[3] These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.

The definition is pretty vague and is hotly contested among astronomers. For the moment it’s what we have.

Pluto 🙁

This new definition meant that Pluto was no longer a Planet but now a Dwarf planet.

This has prompted endless sad Pluto images and t-shirts. 

Pluto now has friends

I’m tempted to say, “Things change get over it!” But that would be me being mean.

Instead let’s reflect on how Pluto used to be the odd one out. Not really an earthy planet not a gas planet. It was like that one Star Trek nerd in a group of Star Wars nerd (trust me this was a big thing 10-20 years ago). But now it’s part of the Dwarf planets and has friends that are the same. Instead of thinking of Pluto being separated from his previous friends, think of it as being allowed to hang out with new friends.

The confirmed Dwarf Planets Friends of Pluto are: Ceres, Haumea, Makemake, and Eris.

Pluto is such a good host that there are another 6 Trans-Neptunian Objects, trying to join its club.

There’s even a sub-category of Trans-Neptunian Objects called Plutinos which are in orbital resonances with Neptune, as seen from the current satellite images. I call these its family.

In Conclusion

Don’t think of Pluto becoming a Dwarf Planet as it being excluded from the Planet Club but think of it as becoming the president of the Dwarf Planet Club.

Did you take the reclassification of Pluto personally?

P.S. Kind advise for you: visit Family Funtures for buying nice home telescope, if you like space as I do!:)

Éric