Sciency Words: Planet (An A to Z Challenge Post)

April 19, 2017

Today’s post is a special A to Z Challenge edition of Sciency Words, an ongoing series here on Planet Pailly where we take a look at some interesting science or science related term so we can all expand our scientific vocabularies together. In today’s post, P is for:

PLANET

In 2006, the International Astronomy Union approved a new, official definition of planet, and Pluto didn’t make the cut. Word has it Pluto took the news well.

The I.A.U.’s concern at the time was that more and more small, Pluto-like objects were being discovered, making Pluto seem less like the ninth planet and more like the first of some new class of thing.

To be fair, the I.A.U. did try to come up with a planet definition that would include Pluto while excluding the dozens or perhaps hundreds of other objects potentially out there. But it just didn’t work out.

So to meet the official, I.A.U. sanctioned definition, an astronomical body must meet three requirements:

  • It must orbit the Sun.
  • It must be spherical, due to the pull of its own gravity.
  • It must have cleared its orbital path of debris (this is the part of the planet test that Pluto failed).

Of course, if a definition can be changed once, it can be changed again. Recently, a group of six NASA scientists—specifically, six scientists from NASA’s New Horizons mission to Pluto—put forward a new proposal, which reads:

  • A planet is a sub-stellar mass body that has never undergone nuclear fusion and that has sufficient self-gravitation to assume a spheroidal shape adequately described by a triaxial ellipsoid regardless of its orbital parameters.

In other words, if it’s round, and it’s not a star or wasn’t a star at some point in the past, then it’s a planet. Under this new definition, Pluto’s back in the planet club! And so is the Moon, weirdly enough, along with many other moons elsewhere in the Solar System. In fact, the new definition would reclassify over one hundred Solar System objects as planets—possibly more than that.

The next I.A.U. general assembly meeting will be held in August, 2018. If they’re going to change the definition of planet again, that’s when they’ll do it. But I very much doubt it’ll happen.

Even though this is probably a lost cause, I want to say something in defense of the New Horizons team’s proposal. The strongest objection seems to be that moons should not be planets. I get that, but in my mind any world that I can picture myself standing on or walking on… I don’t know, that just feels planet-y to me.

I frequently catch myself calling Titan and Europa planets, even though they’re moons. Same for Pluto, Eris, Ceres, and all the other objects currently in the dwarf planet category. And I can’t help myself, but I keep calling Endor from Star Wars a planet, even though it’s specifically referred to multiple times in dialogue as a “forest moon.” All of these places—even fictional moons like Endor—feel planet-y to me.

And yes, even the Moon—the most quintessential moon of them all—has a certain planet-esque quality to it when I imagine myself living there, walking around, going about my daily business. I could get used to the Moon being a planet.

Next time on Sciency Words: A to Z, we’ll shrink from planet-scale to the scale of subatomic particles, and we’ll find out what’s so quantum about quantum mechanics.


Mars vs. the Moon: Where Do You Want to Go?

April 27, 2016

Okay, fellow humans. Where should we go next? Should we return to the Moon or push onward to Mars?

Ap12 Mars vs the Moon

It would be nice if we could do both, but space exploration is expensive. So at least in the near future, we as a species will probably have to choose.

If you pay any attention to NASA’s public relations, you know the United States is aimed for Mars. Almost every new piece of NASA tech is billed as Mars-ready or Mars-capable. Almost every experiment, including Scott Kelly’s Year in Space mission, is somehow Mars related. NASA has produced tons of videos, posters, and infographics, and they’ve made #JourneytoMars a thing on Twitter.

But an actual Mars landing is still at least twenty years away. A lot could happen in twenty years, politically and economically speaking. Regarding the politics of space exploration, international partnerships play a key role. Big, expensive projects become a lot more feasible when costs are divvied up among multiple countries.

Right now, the European Space Agency (ESA) is mulling over the idea of establishing a permanent outpost on the Moon. This moon base, or “moon village” as it’s sometimes called, would be the successor to the International Space Station.

If ESA does get their moon village started, no doubt the Russians and the Japanese will want to be part of it. And so will the U.S. But where will that leave NASA’s #JourneytoMars ambitions?

Personally, I’d really like human beings to finally set foot on Mars, preferably in my lifetime. But ESA’s moon base proposal seems more achievable in the near-term. In a way, it does feel like a logical next step after the International Space Station. But that’s just my opinion.

So what do you think? Were do you, fellow humans, want to go next: back to the Moon or onward to Mars?


Sciency Words: Dark Side of the Moon

April 1, 2016

Sciency Words PHYS copy

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us all expand our scientific vocabularies together. Today’s term is:

THE DARK SIDE OF THE MOON

As the Moon orbits the Earth, the same side of the Moon is always facing toward us. It’s like the Moon is staring at us, unblinking, perhaps with some awkward question it’s been meaning to ask.

My06 Stuff on the Moon

But what’s on the other side? What’s on the side facing away from us? Scientists call that the “dark side” of the Moon. Scientists love making Star Wars references, and this one really fits. The dark side of the Moon is cloaked in perpetual darkness, because it is not only turned away from Earth but also away from the Sun.

As a result, we don’t really know much about the dark side of the Moon. There have been rumors that the Apollo Missions, while in lunar orbit, observed secret alien bases in the Moon’s dark region. This is obvious nonsense. The dark side of the Moon is too dark to observe anything!

Maybe some day when humanity finally chooses to return to the Moon, we’ll get some answers. Just so long as we remember to bring a flashlight.

P.S.: Happy April 1st! No, there is no such thing as a “dark side of the Moon.” The side of the Moon facing away from Earth is properly called the “far side of the Moon,” and it gets just as much sunlight as the side facing us.