Written by Kelly Herbst, Astronomy Curator for the Virginia Living Museum. Updated every two weeks, more or less.

Wednesday, December 18, 2013

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 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

Friday, December 6, 2013


HAHAHAHAHAHA!  We have a comet after all...somewhat.

So Comet ISON did not survive its close brush with the Sun.  And on solar approach, it didn't really get bright enough for us to see in our sky until it was much too close to our Sun.  So...phooey.

However, Comet Lovejoy, one of several by that name (the official name of this one is C/2013 R1)...a much less touted also currently in our sky.  It too, is approaching the Sun, with perihelion coming on Christmas Day.  The big difference here is...this comet might actually be visible in our sky!

Comet Lovejoy is currently a magnitude 4 object in the constellation Corona Borealis.  That puts the comet above the threshold for naked eye visibility.  You'll want a dark sky location to get the best view - anywhere that you can get away from bright sources of light will work.  And of course, the best time to see the comet is in the wee small hours before dawn.

But still!  It's a comet!  HA!

Comet Lovejoy has already made its closest approach to Earth.  But as it draws closer to the Sun, its brightness may continue to increase, meaning that the comet may be on a path to looking better and better in our early morning skies.  Since Lovejoy will only get about as close to the Sun as Mercury, it might even survive and continue to put on a good show into the new year.  Stay tuned!

This finder chart will help you locate Comet Lovejoy in the morning sky:

Finder chart for Comet Lovejoy.  Courtesy
Note that the chart shows three comets in this region...the only one you will be able to see is Comet Lovejoy.  At least a pair of binoculars will be needed to see either ISON or Linear X1.  Lovejoy has a decidedly greenish appearance and should be nicely visible from a dark location.

Best of luck seeing the comet!  If things continue to improve, we'll do a comet-watching event, so stay tuned for more details.

Carpe noctem!

Wednesday, December 4, 2013

Comet ISON Post-Mortem


No, it's not the holiday's the lack of a comet.

Sadly, it looks like Comet ISON did not fare too well in its first ever (and probably last ever!) trip around the Sun.  The comet was brightening dramatically as it approached the Sun, but then even before perihelion (it's point of closest approach to the Sun) the comet suddenly dropped in brightness...not usually a good sign.  It often heralds a breakup of the object.

Thanksgiving Day saw ISON directly behind the Sun from our view at perihelion...and then, it came back!  But sadly it was much, much dimmer than when it rounded the Sun, and then it proceeded to continue to dim rapidly.  Whatever is left of Comet ISON will not be bright enough to put on any kind of display in our skies this December.

A movie of Comet ISON plunging toward the Sun and then emerging, much diminished, on the other side.  Courtesy NASA and the SOHO Spacecraft.

Ah well.  It was exciting to hope for...but it wasn't meant to be.

We've got holiday fun to cheer us up though - Star of Wonder: Mystery of the Christmas Star and Laser Holidays are back in the planetarium for the rest of this year.  And of course, the December Star Party (December 14) will feature not only those two shows, but also a free concert by the United States Salvation Army Brass Band.  And hopefully the skies will be crisp and clear so we can enjoy the natural celestial show as well.

Still, a nice bright naked-eye comet would have been a wonderful early Christmas present.  Maybe if we're lucky, the Geminid meteor shower will consent to give us a few good meteors on December 14th, despite the nearly Full Moon.  Come join us and find out!

More from the world of astronomy in two weeks...until then...
Carpe Noctem!