The Solar System Gets a Makeover

This is how the solar system looked when I was a kid.

Don’t feel bad if you missed it.  You had a lot going on, what with the holiday and all, so when astronomers announced recently that the dwarf planet Makemake has no significant atmosphere it must have slipped past you.

At least you knew there is a dwarf planet called Makemake, and that it’s pronounced “MA-kay-MA-kay”.  I’m ashamed to admit that I was ignorant of its existence.

When I was a kid, there were nine planets and we could name them in order, based on their proximity to the sun.  There was Mercury, Venus, Earth, Mars.  Then came the asteroid belt, a name that generated much schoolboy humor.

Beyond that were the massive Jupiter, ringed Saturn, Uranus (another source of childish jokes), Neptune, and finally Pluto.  That was the lineup until a few years ago, when the International Astronomical Union demoted Pluto, recategorizing it as a “dwarf planet”.

Pluto had only been discovered in 1930, so it didn’t get to hang out with the varsity planets very long.  Its name, by the way, was suggested by Venetia Burney, an 11-year-old schoolgirl in England who obviously had some experience with unusual names.

In classical mythology, Pluto was the Latin name for the ruler of the underworld.  It wasn’t until several months after the naming of the planet that Walt Disney appropriated the name for the beloved cartoon dog character.

Anyway, at the time astronomers found it, Pluto (the planet) was believed to be about the same size as Earth.  As telescopes and technology have improved, though, scientists realized that it is less than 20% as big as the planet we call home.

By focusing their attention in Pluto’s part of the universe during the early 1990s, astronomers discovered something now known as Kuiper’s belt (to my knowledge, no Disney character has been named “Kuiper” yet).  Within that band of ice and rocks 3 billion miles or so from the sun, other petite planets were seen.

With these developments, the International Astronomical Union decided it was time to render my astronomy textbooks obsolete.  As mentioned, Pluto was downgraded in 2006, and at the same time, an asteroid known as Ceres was upgraded to dwarf planet.  Another orbiting object that was discovered in 2005 and subsequently named Eris is categorized that way, too.

In 2008, the IAU dwarf planet collection added Haumea, named for the Hawaiian goddess of childbirth, and Makemake, a name given by the Rapa Nui people of Easter Island to their god of fertility.  It’s a long way out there — Makemake completes an orbit around the sun every 310 years, give or take.

As of today, then, the solar system floor plan is down to eight planets and their moons, and five official dwarf planets, with several more awaiting confirmation by the IAU.

Oh, and if you’re concerned about the news from Makemake, Science.com reports that “although this icy world currently lacks an atmosphere, there is still a chance it could form one.”  Keep your fingers crossed!

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