EDUCATION NEWS

Expanding Knowledge, Expanding Nomenclature: We all know about the “demotion” of Pluto from planetary status, even if we do not agree about it. Personally, I believe that making such changes in nomenclature is a necessary and proper reflection of our expanding knowledge of the nature of the Solar System, and I like to use as an analogy the actions taken during a spring cleaning of my garage (as long-time A+StW readers will recall). 

In a nutshell: The way to clean out a garage is to remove everything in it to a staging area outside, where you sort things out. You knew that there were several categories of stuff in there, and that you’d want to re-store them in logical groupings. As items come it, it’s likely that you would find items that you had forgotten about and didn’t fit into your pre-cleaning sorting strategy. You’d also likely find that some of the groupings were too large to be stored together, so you might sub-divide that pile for storage.

Categorization is not only the first step in garage-cleaning, it’s also the first step in the process of scientific inquiry.

Ancient astronomers knew the five major planets quite well, and could predict their locations quite accurately, enough so to forecast eclipses and other astronomical events/movements. But occasionally a strange interloper would make a temporary appearance, causing consternation all around. Most of these objects received the name, “comet,” or “hairy stars,” based on their appearance. Galileo showed that at least some planets have smaller objects, moons, orbiting them. And starting in 1801, astronomers found a group of small objects orbiting (mostly) between Mars and Jupiter. So the nomenclature had to expand from “stars and planets” in the sky to “stars, planets, moons, asteroids, and comets” in the sky.

Astronomers also knew that something strange was going on in the Solar System’s outer reaches, even if they at first didn’t know enough to “clean out the garage.” Uranus’ obliquity was unlike any other planet’s, Neptune’s large moon, Triton, has a retrograde orbit that is decaying, and Pluto’s orbit is more elliptical than the orbits of the planets and is inclined to the Plane of the Ecliptic much more than any of the planets.

The discovery of Kuiper Belt objects “muddied the crick” considerably. So did the recognition of “active asteroids” that blur the line between “asteroids” and “comets.” So did the recognition that Jupiter’s gravity has an enormous effect on the evolution of the Solar System. But that’s a good thing, too, because it reflects an increase in our understanding of the nature of the Solar System as a whole.

Trans-Neptunian planets are more like Pluto, Charon, Arrokoth, and other distant objects (KBOs). They are rich in volatile materials because they have never been heated by the Sun to any extent. Comet C/2014 UN271 Bernardinelli-Berntein may be another example. Those that do approach the Sun have highly-elliptical orbits, at least at first.

Blame Jupiter. Its gravity can either eject first-timers (as Comet B-B likely will be) or make their orbits much less elliptical, exposing their surfaces to periodic solar heating and devolatilization. Some will eventually lose so much of their volatiles that they are no longer comets, but rather more asteroidal in nature.

Jupiter’s gravity tends to force shorter-period comets more and more toward the Main Belt. By the time that happens, they are comets no more but asteroids, some still capable of shedding meteoroids, some not.

Those bodies in the transition phase often show characteristics of both comet and asteroid. They are rare because the overall time taken in transition is short compared to the age of the Solar System. Now called “Centaurs,” their discovery played an important role in astronomers figuring out this evolutionary process. 

Most meteor showers we see today are the result of comets shedding rocky debris as they devolatilize, a process that could continue over many orbits. Two bodies very near the end of their activity are the parent bodies for two different showers: the Geminids last month are debris from the asteroid 3200 Phaeton, and the Quadrantids appearing now are debris from the near-Earth asteroid 2004 EH.

Astronomers are now had to consider a more comprehensive classification scheme.

KBOs did not cleanly fit into the planet, moon, asteroid, comet naming scheme. At least one of them, Eris, was larger than Pluto, and some of them had much more elliptical orbits than others like Pluto. And the first asteroid to be discovered, Ceres, was so large that its gravity made it spherical; the others are irregularly shaped.

The International Astronomical Union is the “official” arbiter of Solar System nomenclature. They made a series of decisions two decades ago about categories of Solar System objects, expanding the categories to include “dwarf planets” and recognizing that the line between “asteroids” and “comets” was blurred, so they are lumped together as “Small Solar System Bodies.”

Public outcry ensued. “Poor little Pluto! We want nine planets again!” But there was no way the original nine planets could be defined in a way that would allow Pluto to remain a planet and Ceres, Eris, and perhaps other KBOs not become planets. It was either eight or “many.” The IAU chose eight, and made Ceres, Eris, and the other large KBOs to be “dwarf planets.” The mnemonic “My Very Educated Mother Just Served Us Nine Pizzas” had to become “My Very Educated Mother Just Served Us Nachos!”

IMO, the public interest in the “demotion” of Pluto is an outstanding opportunity to demonstrate to the public how scientific inquiry operates!

For details on the IAU nomenclature scheme, see: https://iauarchive.eso.org/public/themes/pluto. The January, 2022, issue of Sky and Telescope (pages 14-19) has an excellent description of this whole issue, written by Kat Volk at the University of Arizona’s Lunar and Planetary Laboratory.

The whole Uranus, Triton, Pluto thing will continue to refine our understanding. New telescopes are allowing the discover of a number of new KBOs. Most have elliptical orbits that lie ~40 AU from the Sun. But a group of KBOs are much farther out, on the order of 100 AU; the latter are informally named Extreme KBOs. We’ll see how the IAU accommodates these new discoveries and the discoveries to come.

Science marches on! 

Smithsonian Educational Programs for Early Learners! Smithsonian Magazine recently posted a piece about 13 innovative programs for early learners at downtown DC’s SI Units. There are a number of wonderful opportunities for helping visiting families inspire the children’s learning. I’m personally familiar with the National Air and Space Museum’s “Flights of Fancy Story Time’ (offered at both NASM sites, downtown and the Udvar-Hazy Center) and “Soar Together at Air and Space.” Check out the Magazine’s article here: https://www.smithsonianmag.com/blogs/smithsonian-education/2024/05/07 ; it contains links to get more information about specific programs. [Congratulations to A and D!]

Follow-Up: Check out NASM’s latest Flights of Fancy Story Time, about “Spacey Science Experiments,” here. The Flights of Fancy Storytime’s playlist is here. NASM also offers “Music Time,” “Craft Time,” and “Looking Closely” (at objects from the NASM collection).

These are wonderful things for (grand)parents to share with their young ones!

Make Your Own Paper Models of Spacecraft: You can download and print pdf files with instructions and templates to produce 3-D models of Chandra, Compton, Fermi, the HST, and even the JWST and more! Learning retention increases with making such things! See: https://www.nasa.gov/stem-content/universe-spacecraft-paper-models. These make great (grand)parent-child projects!

Follow Up: Michael Hulslander, my friend and former colleague at NASM, has written a book, “Smithsonian Book of Paper Air Planes.” And these aren’t just the simple designs we made as kids; Mike’s designs are inspired by actual aircraft! Like NASA’s spacecraft, making them would be a wonderful family activity, both educational and fun. Find out more about the book from his piece in Smithsonian Magazine (https://www.smithsonianmag.com/blogs/smithsonian-books/2025/02/13/Now-You-Can-Fold-Planes-from-the-National-Air-and-Space-Museum-and-Watch-them-Fly). Get your own copy from retailers working with Smithsonian Books, here: https://www.smithsonianbooks.com/store/smithsonian/smithsonian-book-of-paper-airplanes.

Student Built CubeSat Scores! Ireland’s first-ever satellite was built by students at the University of Dublin, and launched last December. EIRSAT-1 was designed, built, and tested under the guidance of ESA Education Division’s “Fly Your Satellite” program. EIRSAT-1 carries several instruments, including a gamma ray detector. On August 21, 2024, it detected two gamma ray bursts 80 seconds apart. Other spacecraft and ground-based assets confirmed the observation, and more detailed study determined the likely cause was a merger of two neutron stars over 3 billion light-years away. Now THAT’s a cool student project!

Celebrate the Heliophysics Big Year with Free Heliophysics and Math Webinars from NASA! Find out more at: https://science.nasa.gov/learning-resources/science-activation/celebrate-the-heliophysics-big-year-with-free-heliophysics-and-math-webinars-from-nasa-heat.