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

The Year in Review

It's that time of year, isn't it folks?  Everyone is doing a "Year in Review."  Well, who I am to miss that bandwagon!  So in this final installment of Cosmic Strings for 2011, I give you my personal five favorite astronomy stories of 2011.  Enjoy!


The Total Lunar Eclipse of June, 15, 2011
2011 was a banner year for eclipses...we had 4 solar and 2 lunar eclipses.  I wish we could have seen them.  Sadly, all 6 eclipses were basically not observable from the United States.  But many of our international friends got to see some amazing sights...and of the the eclipses this past year, the June 15th lunar eclipse was likely the most wonderful.  It was a rare lunar eclipse where Moon passed through virtually the exact center of the Earth's shadow, making it not only a very long eclipse (the total duration was almost 6 hours!), but also one where the Moon took on a fabulous color.

The lunar eclipse of June 15, 2011 by Javier Algarra.  Courtesy Astronomy Picture of the Day.

Atmospheric scientists can tell a great deal about the Earth's atmosphere from lunar eclipses.  The reddish color of the Moon during a lunar eclipse is caused by sunlight bending through the Earth's atmosphere and striking the lunar surface even when it is in the shadow of the Earth.  Usually only deep reddish light gets through, but depending on the various particulates found in the atmosphere of the Earth, the Moon may appear bright red, copper colored, and even a yellowish-orange.  If you got to see this wonderful eclipse, count yourself lucky!

The Launch of Curiosity
It might seem odd to include a spacecraft launch in my list, but I can't help it.  I'm excited!  Another plucky robot has successfully made it off the Earth and is on its way to Mars.  Launch is a dangerous time...second only in danger to landing.  So Curiosity still has a long way to go before it can get to work...and the greatest danger lies ahead.  Mars has been a tough planet to explore...about half of the missions headed there have ended badly.  And yet, Mars is well worth the effort, as it is the place in the solar system most like the Earth.  If life is, or ever was, present in the solar system beyond the Earth, Mars is the most likely place for it.  The Spirit and Opportunity rovers have shown us definitive proof that Mars was wet in the past and likely still has a fair amount of water.  Perhaps Curiosity will be able to provide definitive evidence of Martian life!  If so, that will certainly make the list in 2012!

The launch of the Mars Science Laboratory rover, called Curiosity.  Courtesy NASA.

The Uncookable Comet Lovejoy
A late entry - but an amazing one!  Kreutz sungrazer Comet Lovejoy was discovered by Australia's Terry Lovejoy a bit less than a month before its close encounter with the Sun.  No one expected the cosmic chunk of ice and rock to survive its passage a mere 87,000 miles above the solar surface (Earth is on average 93 million miles from the Sun and I can still get a sunburn in the winter!) on December 16.  But as I write this, Comet Lovejoy is still kicking, headed away from the Sun and sporting an enormous tail.  Sadly, we can't see it very well from here in the United States, but its discoverer is still getting a nice view!  Southern hemisphere dwellers - get outside before the sunrise and enjoy the view of Comet Lovejoy in the east.  It's well worth the effort!

Comet Lovejoy after its incredible solar encounter by Kosma Coronaios. Courtesy spaceweather.com

Pluto May Not Be a Planet...But it is a Moon Magnet!
First among dwarf planets Pluto was back in the news again this year - sporting a newly discovered moon.  The intrepid Hubble Space Telescope was searching for rings around the tiny body, but instead discovered a fourth moon circling this enigmatic little world.  Officially announced on July 20, 2011, little S/2011 P4 doesn't yet have a proper name.  But its discovery confirms that this world, though no longer considered a major planet, will remain a target for scientific curiosity and discovery for years to come.  New Horizons will arrive in 2015, increasing our understanding of the Plutonian system exponentially.  I can't wait!

The discovery of Pluto's newest moon, S2011/P4.  Courtesy STSci.

The End of an Era: NASA Retires the Space Shuttle
For 30 years, manned spaceflight was synonymous with the Space Shuttle.  NASA's fleet of launch-like-a-rocket-land-like-a-glider spacecraft were amazing machines, completing 135 missions to space, launching innumerable satellites and spacecraft, conducting thousands of experiments, and performing 37 construction and service visits to the International Space Station.  Groundbreaking mission like those of the Galileo spacecraft and the Hubble Space Telescope started with a launch from the cargo bay of a space shuttle.  While we mourn the loss of the 14 astronauts who died in the Challenger and Columbia tragedies, we must also acknowledge that the shuttle's work record of 30 years is nothing short of extraordinary.

Space Shuttle Discovery.  Courtesy NASA.

Now the United States has no manned spaceflight capability,. and the future of human exploration of space has never looked more bleak.  No other space agency has the same level of experience which NASA has in manned spaceflight.  But we will lose those skills rapidly if we can no longer send people into space to use them.  While NASA is actively seeking new astronauts, I wonder what they will do, since they must rely on the faltering Russian space agency to successfully carry them into space.  Human space exploration fires the imagination like few other things can, and the technological spinoffs from such efforts are too numerous to detail.  I hope that our government will be willing to make an investment in a future they can't imagine now, and not let the problems of today kill the dreams of tomorrow.

I wish you all a wonderful holiday season full of family, friends, love and joy.  And may 2012 be a truly stellar year for us all.
Carpe annum!
Kelly

Over the Moon

Actually, I'm kind of not.

We had an amazing night last Saturday, observing the Moon.  The NASA exhibit was awesome...I touched a piece of the Moon!  Our Moon is incredible!

And that got me thinking...what about all the other moons?  Does anybody realize how incredibly awesome they are?

We tend to focus on our own Moon.  Makes sense...it's big, bright, and plays an important role in the existence of life here on Earth.  But among the major planets there are 168 other moons...all equally fascinating worlds in their own right!  So let's explore some of the other moons out there...and kind of play a little compare and contrast with our Moon, if you will.

Earth has one moon.  That's it...just The Moon.  Most of the other planets have many more moons indeed...Jupiter takes the prize for the most (if you don't count ring particles!) at 64 known satellites.  Even Mars has 2 moons - double what we've got!  The only planets with fewer moons than Earth are Mercury and Venus - neither world has any moons at all. 

Size matters though...Mars' two moons are extraordinarily tiny.  Phobos (Fear) and Deimos (Panic), as the Martian moons are named, are most likely captured asteroids.  They are small potato-shaped bodies, barely findable in a telescope from here on Earth...and even then only when Mars makes a close approach to us.  Such jagged chunks of stuff can be found orbiting all of the gas giant planets as well...the majority of the solar system's moons are weird little lumpy leftovers from the formation of the planets.

Phobos (top) and Deimos (bottom).  Courtesy NASA.

On the other hand, our Moon is not the largest in the solar system, either.  That distinction goes to Ganymede, largest moon of Jupiter.  In fact, Ganymede is larger than the smallest major planet...at 3,280 miles across it beats Mercury's size by more than 200 miles.  This massive moon is truly a world in its own right...it shows evidence of tectonic activity, its own magnetic field, and it might even have an atmosphere.  Talk about your colossal moon!

Ganymede from the Galileo spacecraft.  Courtesy NASA.

Speaking of atmosphere, our Moon hasn't got one.  If you plan on visiting the Moon, make sure you bring your own air.  The moon with the densest atmosphere?  Saturn's enigmatic Titan.  The moon, explored by the Huygens lander, has the distinction of being the only moon known with an atmosphere consisting of more than trace gases.  It is a dense soup of hydrocarbons, with numerous distinct layers...shrouding the moon and looking like a heavy layer of orange smog.  So impressive is this moon's atmosphere that it is believed to be, like Venus, a super-rotator - that is, the atmosphere actually rotates much faster than the moon itself does.  The Huygens probe showed us incredible details about Titan, but so much more remains to be learned.

Titan from the Cassini spacecraft.  Courtesy NASA.

The surface of Titan from the Huygens probe.  Courtesy NASA/ESA.

Keep in mind, we've limited ourselves at this point to explore the moons of the major planets.  There are more moons than that in the solar system!  Of the 5 confirmed dwarf planets, 3 have moons: Eris has Dysnomia, Haumea has Namaka and Hi'iaka, and Pluto has Charon, Hydra, Nix, and the newly discovered P4 (it's so new it doesn't have a name yet!).  Pluto is only 2/3rds the size of our Moon - and it has 4 moons of its own!  Incredible!

Pluto and its 4 moons from the Hubble Space Telescope.  Courtesy NASA.

Oh, so you think only planets, be they major or dwarf, can have moons?  Not so...the asteroid Ida has a moon, Dactyl, first discovered by the Galileo spacecraft as it passed by on its way to Jupiter.  The solar system is rich with moons!  Take some time to explore them...both by reading up on them and by checking them out through telescopes - the moons of Jupiter and Saturn can easily be seen in telescopes from Earth!

Ida and its tiny moon Dactyl from the Galileo spacecraft.  Courtesy NASA.

Have fun mooning around, and I'll see you next time!
Carpe noctem,
Kelly