What's In a Name?

Xena.  2003 UB313.  Eris.

These names all refer to the same astronomical body - a dwarf planet located out near Pluto.  "Xena" was the nickname given to the little world by its discoverer, Mike Brown.  2003 UB313 was its official designation until an official name, Eris, was given to it in  2006. Okay, well...technically, the body's official official name is 136199 Eris.

Eris and its moon Dysnomia, as seen by the Hubble Space Telescope.  Courtesy Wikipedia.

Why all the fuss over a name?

In the astronomical community, names are important things.  For many of the same reasons they are important beyond the astronomical community too.  We need names to know what we're talking about.  If everyone had a different set of names for all the different objects in the solar system, well, it would make doing a live planetarium show a lot tougher, let me tell you.  Scientists around the world need a consistent set of names for things so they can share information with colleagues around the world. 

Names can also be used to honor different groups of people as well.  We like a certain consistency in that.  For example, all of the features on Venus are named for women.  Mostly goddess from various mythologies around the world, but also for famous women, and even some just commonly used women's names.  Of course, any convention just begs for exceptions.  Venus has three - all features that were named before the naming convention was put into use.  Two regions on Venus, Alpha Regio and Beta Regio, are simply named for the first two letters in the Greek alphabet.  There is only one feature on Venus named for a man - Maxwell Montes, named for physicist James Clerk Maxwell.

A radar image of Maxwell Montes on Venus - the only feature there named for a man.  Courtesy Wikipedia

Scientists are by nature organizers...we like to sort things into categories and name them all the same.  For example, the naming convention for moons of Uranus is to name them for Shakespearean sprites and fairies.  Thus the planet has moons like Puck, Oberon, Titania, and Ariel. 

Uranus and its 6 largest moons - from left to right, Puck, Miranda, Ariel, Umbriel, Titania and Oberon.  Courtesy Wikipedia.

So who comes up with all this?

The governing body for astronomical science, the International Astronomical Union (IAU), puts together all the rules and regulations for how to name things, and gives official approval to the names of new objects. The IAU's Working Group for Planetary System Nomenclature (WGPSN) handles things within our solar system.  Names can be submitted to the WGPSN, and then they recommend them for approval by the General Assembly or reject them.  A name is not official until it has been approved by the General Assembly.

In general, the working rules for submitting a name to the WGPSN are:

1. Nomenclature is a tool and the first consideration should be to make it simple, clear, and unambiguous.
2. Features whose longest dimension is less than 100 meters are not assigned official names unless they have exceptional scientific interest.
3. The number of names chosen for each body should be kept to a minimum, and their placement governed by the requirements of the scientific community.
4. Duplication of the same name on two or more bodies is to be avoided.
5. Individual names chosen for each body should be expressed in the language of origin. Transliteration for various alphabets should be given, but there will be no translation from one language to another.
6. Where possible, the themes established in early solar system nomenclature should be used and expanded on.
7. Solar system nomenclature should be international in its choice of names. Recommendations submitted to the IAU national committees will be considered, but final selection of the names is the responsibility of the International Astronomical Union. The WGPSN strongly supports equitable selection of names from ethnic groups/countries on each map; however, a higher percentage of names from the country planning a landing is allowed on landing site maps.
8. No names having political, military or religious significance may be used, except for names of political figures prior to the 19th century. (Note: Apparently this only goes for religions that are widely practiced today, since gods and goddesses of ancient religions are obviously acceptable to the IAU.)
9. Commemoration of persons on planetary bodies should not be a goal in itself but should be reserved for persons of high and enduring international standing. Persons being so honored must have been deceased for at least three years.
10. When more than one spelling of a name is extant, the spelling preferred by the person, or used in an authoritative reference, should be used. Diacritical marks are a necessary part of a name and will be used.
11. Ring and ring-gap nomenclature and names for newly discovered satellites are developed in joint deliberation between WGPSN and IAU Commission 20. Names will not be assigned to satellites until their orbital elements are reasonably well known or definite features have been identified on them.

Pretty intense, just to give something out there a name, huh?

The IAU has come under fire for a very big renaming - the recelassification of Pluto as a dwarf planet.  The IAU is also responsible for the definitions of things...like the word "planet."  It's a work in progress, and many people think the IAU's definition of planet is still not right.  Pluto got moved into the dwarf planet category because the IAU defined a planet as having cleared its orbital area of similarly-sized bodies.   Pluto has several other objects of similar size (some of which are now dwarf planets, too) orbiting nearby, so it couldn't pass that part of the definition.  This same definition also places a requirement on a planet that it orbits the Sun.  That might seem like a no-brainer...until we remember that many other stars besides the Sun have big worlds going around them too.  Are these worlds not planets, simply because they orbit around another star?  Clearly, the definition of planet still needs a bit of tweaking. 

But that's why the IAU is there...and that's what science is all about.  As our understanding grows and changes, so also must our definitions, names and descriptions.  It's all part of the messy process of learning we call science.

When I first started working in the astronomy group at the Virginia Living Museum, I was young, and still working on my Ph.D.  The guys in the astronomy group called me "Astrogirl" - a nickname I still frequently use.  But I've been with the museum over 20 years now, volunteer to Astronomy Curator, and I'm probably getting a bit old for a nickname that prominently features the word "girl."  I think I might move up to a new one, bestowed upon me by one of the herpetologists here at the museum.

More from the cosmos in two weeks...until then...
Carpe Noctem!
Kelly, The Sky Doctor

I'm Sorry I'm Confused...

Well, hello!

Sorry about the lack of a post two weeks ago...I wrote one, but for some reason Blogger never posted it.  I've gotten so used to this thing working so well, I never thought to check to see if the scheduled post properly popped up!  I'll have to be more diligent with this thing in future.

I am smack dab in the middle of summer camps this week.  I'm currently teaching rising first and second graders about the planets - and it's TONS of fun!  I love working with kids...they always seem to know way more than I think they will.  It's awesome.

Anyway, since I've got planets on the brain, I thought I'd share a few tidbits about planets that my kids know...but maybe some of our grownups out there don't!  Enjoy!

Did you know...

...Mercury has a thin "borrowed" atmosphere of solar wind surrounding it.  The gases streaming away from the Sun will wrap around Mercury for a little while before continuing their journey through space.  It's not a very nice hug, however...the impact of the gaseous material can blast sodium ions off the surface of the planet!

...Venus rotates backward.  Something quite traumatic must have happened to our neighbor in its early history, as the planet appears to have been tipped completely over by a massive impact.  This same event massively slowed Venus' rotation as well, leaving it with a day which is longer than its year!

...Earth has been visited by spacecraft more times than any other planet.  Indeed, the majority of the spacecraft launched by the various space agencies around the world have been placed in orbit around our home planet for a wide variety of purposes, including scientific study.

...Mars is only half the diameter of Earth.  The much-maligned Red Planet - long considered the home of aliens bent on taking over the Earth to gain its vast supply of precious water - actually boasts several geologic superlatives despite its small size.  Mars is home to one of the largest canyons in the solar system (the Valles Marineris - large enough to stretch from New York City to Los Angeles if placed here on Earth!) as well as the largest volcano in the solar system (Olympus Mons - standing two and a half times the height of Mt. Everest and with a base as large as the state of Virginia!).

...Jupiter has the longest-lived cyclonic storm ever seen.  The Great Red Spot on Jupiter is actually a storm that has been raging in the atmosphere of the giant planet for more than 400 years - at a minimum!  Galileo Galilei first noted the presence of the storm in 1609 when he observed the giant planet through his simple telescope...but of course, since he was the first person ever to see Jupiter in that way, we have no idea how long the storm had been there before he saw it.  The Great Red Spot continues to fascinate amateur and professional astronomers alike to this day.

...Saturn has such a low density that you could float it in a bathtub...if you could find one big enough!  Though the second largest planet in the solar system, Saturn is less dense than water.  So if we could get enough water together, Saturn could float in it.

...Uranus rotates on its side!  Like Venus, it appears this planet also suffered a major whack early on...resulting in an orbital tilt of 98 degrees.  So the moons and rings of Uranus appear vertically around the planet, rather than the horizontal aspect we might expect.

Uranus - the Sideways Planet!  Courtesy NASA.

...Neptune used to have an enormous hurricane too...but now it's gone!  When seen by the Voyager spacecraft in 1989, Neptune boasted the Great Dark Spot, an atmospheric storm of some kind that appeared as a darker blue splotch on the planet.  In 1995, Hubble was aimed at the 8th planet, hoping to get a another look at the dark spot - but it was nowhere to be seen.  Unlike Jupiter, Neptune's storms seem to be short-lived things.

And we really can't finish out a post about planets without mentioning the dwarf planets!  There are officially five dwarf planets in the solar system these days - Ceres, the largest of the asteroids, and 4 Kuiper Belt objects - Pluto, Haumea, Makemake, and Eris.

Pluto now boasts five moons of its own - and they all finally have official names!  Recently, the International Astronomical Union officially named the two moons discovered in 2011 and 2012...so Pluto is now attended by Charon, Hydra, Nix, Kerberos, and Styx.  Not bad for the premiere dwarf planet of the solar system!

Pluto, now a virtual mini solar system of its own.  Courtesy NASA.

Well, that's about all I have time for just now.  Hope you discovered a little something new about the solar system in which you live!  See you in two weeks...assuming Blogger doesn't go crazy on me again.

Until then...Carpe Noctem!
Kelly