1 – Asteroids
Eärendil does not sail the Dome alone, and that ought to put a smile on his face.
Sometimes astronomers go geek and draw the names of their discoveries from Middle-earth. Thus Eärendil's fellow sky-wanderers range from the brain-bursting big to the simple 'n small. Some of the very smallest are asteroids.
What follows is more than you ever wanted to know about asteroids, but you can skip 7 paragraphs down to the meat if you like.
Asteroids are space rocks, aka "minor planets," that orbit the sun. They can reside anywhere in the Solar System, but most hang out between the orbits of Jupiter and Mars.
Through a telescope, they look like any other star. You'd only know for sure it's a space rock if you sketched or photographed the surrounding star field and came back after some days. If one of the stars has "hopped" you may have an asteroid.
You notice an asteroid's movement because it is nearer than the background stars. It's the same effect you see on the highway – the closer billboards zoom by faster than the more distant pine trees.
That is how many asteroids are discovered: you observe it many nights and calculate its orbit, i.e., its path around the sun. If no other asteroid occupies that orbit, then you've discovered a minor planet. Good for you.
Thousands and thousands of asteroids are known and more are found every day by professional and amateur astronomers alike. Relatively few are named, although that select group still totals to about 15,615. I counted.
All asteroids are given permanent numbers once their orbits are pinned down well enough that astronomers can predict their future positions. Only then can they be given bona fide names. The very first asteroids found in the 1800s were christened after minor female Greek and Roman deities. Nowadays the asteroid's discoverer is allowed to name it whatever non-deity he desires.
And that's good because Roman deities make me blush and I'd be writing about nothing. Just breeze through JPL's Small-Body Database, and you'll find at least two asteroids given Tolkieny names.
First, minor planet 2675 is named after the Professor himself . Discovered in 1982 by an M. Watt, 2675 Tolkien is a Main-Belt Asteroid, meaning it sticks between Jupiter and Mars with no propensity to ever cross Earth and brush Vingilot's mast clean off. (Which would be a funny fanfic, btw).
Tolkien has an absolute magnitude (brightness) of 12.5. You can only see up to magnitude 6.0 with your bare eyes, unfortunately. And the asteroid is probably much, much fainter than even that from our position on Earth. You'll probably need some mega-telescope to glimpse it.
Here's the blurb on Tolkien as given in the Dictionary of Minor Planet Names:
"Named in memory of J.R.R. Tolkien (1892-1973), author and philologist, Merton professor of English language at the University of Oxford. Best known for is imaginative writings, in particular The Lord of the Rings and The Hobbit, he also had a life-long interest in astronomy ."
The second minor planet, 2991, is none other than Bilbo. Also discovered by M. Watt in 1982, 2991 Bilbo is fainter than Tolkien at absolute magnitude 13.5 . Really, that is how it works. Smaller the number, brighter the star-thing; the sun's apparent magnitude, for instance, is a roaring -26.7.
And here's what the minor planet gurus got to say about Bilbo:
"Named for the central character in J. R. R. Tolkien's classic tale of Middle Earth, The Hobbit. The name is proposed by G. V. Williams and is in keeping with the discoverer's first numbered object, (2675) Tolkien ."
Do try the links below to the Small-Body Database pages for Bilbo and Tolkien. You can get nifty Java-powered visuals of their orbits if you click on "show orbit diagram" on the left above the first big blue box.
Asteroids in Tolkien's writing?
Several times Tolkien mentions unearthly black stones, all but calling them by their modern term, "meteorites" – tiny pieces of asteroids that smacked into Earth and lived to tell the tale.
Most meteorites amassed by collectors are composed of a magnet-loving substance, iron-nickel. It's not that iron-nickel meteorites are more plentiful than brown stony meteorites; black iron-nickel rocks make the bulk of findings because they are so easy to spot. If you've watched the show Meteorite Men or have had the privilege to handle an iron space rock, you know that these things aren't just black, they're Morgoth's soul black.
Two examples of likely Middle-earthian meteorites:
-The twin black swords, Anglachel and Anguirel, crafted by the Dark Elf Eöl. They consisted of "iron that fell from heaven as a blazing star." ["Of Túrin Turambar," Silm]
-The Stone of Erech, a black rock reportedly amongst Isildur's luggage in the flight from Númenor. Famous for the provisional oath that the Men of the Mountain swore upon it. It's described as "a black stone, round as a great globe, the height of a man, though its half was buried in the ground. Unearthly it looked, as though it had fallen from the sky..." ["Passing of the Grey Company," RotK]
 Tolkien's Small-Body Database page: http:[double forwardslash]ssd[dot]jpl[dot]nasa[dot]gov[forwardslash]sbdb[dot]cgi?sstr=2675+Tolkien
 Lutz D. Schmade, Dictionary of Minor Planet Names, Volume 1, page 219. (available in Google Books)
 Bilbo's Small-Body Database page: http:[double forwardslash]ssd[dot]jpl[dot]nasa[dot]gov[forwardslash]sbdb[dot]cgi?sstr=2991+Bilbo
 Lutz D. Schmade, Dictionary of Minor Planet Names, Volume 1, page 246.