There Should be a Change in How We Decide What's a Planet and What Is Not

Pluto and it's moon, Charon

The astronomical bigwigs are at it again - trying to decide whether or not Pluto's a planet. I think the wrong people are debating this. Regular folk should decide. This is too important to leave to mere astronomers and academics.

So, let me offer a definition of a planet from the viewpoint of a consumer of astronomy. To be a useful definition, let's make it more like the way the APA describes mental illnesses. It gives some options and the requirement is that the disorder (or planet in this case) meet 3 of 4 or 4 of 7 of the criteria to be that mental disorder or astronomical object. This leaves room for variation within a type. So here's my offering for a definition of a planet.

1. Is a celestial body moving in an elliptical orbit around a star.
2. Is spherical in shape and has a shape that is stable under its own gravity.
3. Is large enough to dominate its orbit having cleared neighboring space of debris.
4. Has at least a diameter of 2,000 km.
5. Has a satellite that orbits around it.
6. Has an atmosphere.

To be a planet, it must meet four out of six of the above criteria.

Pluto would be a planet (1,2,4,5,6)
Eris might be a planet (1,2,4?,5,6?)
Makemake would be a dwarf planet (1,2,)
Quaoar would be a dwarf planet (1,2,5)
Orcus would be a dwarf planet (1,2)
Sedna would be a dwarf planet (1,2,)
Ceres would be a planetoid or asteroid (1)

I might even make a further distinction.

1 criteria = asteroid (mostly because it's not spherical)
2 criteria = planetoid
3 criteria = dwarf planet
In which case Orcus, Makemake and Sedna would be only planetoids.

Just my own humble opinion. It just seems that the requirement that a planet meet every criteria in a list is too rigid. It doesn't allow room for something odd to be a planet even though everybody thinks it ought to be one because it looks like one. That's how things get named out in the real world.

Scientists should remember that before they go around willy-nilly making a kid's model solar system obsolete.

Yeah, it makes me mad. I'm getting too old to relearn the solar system.

© 2014 by Tom King

I'm Not a Physicist, But I Play One in My Head.......

Naming the stuff of the final frontier

I am not a physicist as the title to this piece suggests.  I'm a writer.  That said, since when has a lack of credentials ever stopped a writer from naming things. The term "robot" was invented by a writer. A "waldo" is a mechanical hand, named after a sci-fi story by Robert A. Heinlein.  Writers also gave us words like zero-G, gas giant, terraform, android and its diminutive form - "droid", deep space, computer "virus" and a host of other words.  Even the very idea of orbiting telecommunications satellites, sprang from the mind of a scientist turned writer, the inimitable Arthur C. Clark of "2001 a Space Odyssey" fame.

So in the grand tradition of writers poking their noses into areas they know only enough about to get themselves confused, I am proposing a new handy term for physicists to use for something they don't yet understand.  I know, thoughtful of me, right? 

Here's the problem.  The universe seems to be expanding at a rate that is not so fast that it tears itself apart, nor so slow that gravity collapses everything in on itself but at a speed which, for the sake of a stable cosmos, is "just right".  Physicists have a lot of theories about why this is so, but they don't have a really good term for it, so I am wading into the fray to help at least give us a working word to use when we're talking about it.

I propose we call this "just right" speed of cosmological acceleration the "Goldilocks Expansion Constant". I know, cool right - the whole fairy tale imagery and stuff?

And as to all that so-called "dark energy" they say is driving the Goldilocks Constant?

I call Him God. 

© 2013 by Tom King