27 March 2017
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Martian Curiosities
Martian Curiosities Brine ponds and possible biological activity

Asteroid Facts
[Part I]  Part II

Discovery
On the first evening of 1801, Palermo Observatory director Giuseppe Piazzi noticed an extra star through his telescope among the others in Taurus that didn’t seem to belong there. Its steady movement over the next few evenings convinced him that he had found, at the very least, a new comet.

Piazzi notified other astronomers including Johann Bode, Jèrôme LaLande, and Baron Franz von Zach. Bode was the director of the Berlin Observatory and had published a mathematical “law” describing the relative sizes of the solar system’s orbits including that of a hypothetical planet between Mars and Jupiter. LaLande published planetary tables and had been Piazzi’s teacher, and von Zach edited a widely read astronomical journal and had taken to heart an ancient legend of a missing planet, also between Mars and Jupiter. Sir William Herschel’s discovery of Uranus twenty years earlier was still fresh on everyone’s mind.


Carl Friedrich Gauss
Carl Friedrich Gauss
Piazzi named his object Ceres Ferdinandea after Ceres, the Roman goddess of agriculture, and King Ferdinand III of Sicily. The greater astronomical community, recalling that Herschel had originally named his discovery after Britain’s King George III, met him halfway and jettisoned the Ferdinandea.

Carl Friedrich Gauss derived Ceres’s orbit from Piazzi’s data and found it to vary between 2.5 and 3 astronomical units from the sun, confirming its placement between Mars (1.4 to 1.7 AU) and Jupiter (5 to 5.2 AU). By definition the average earth-sun distance is 1 AU. Modern nomenclature for asteroids whose orbits have been precisely plotted places a numeral for the order of discovery before the name, so you’ll see Piazzi’s discovery listed as 1 Ceres.


Ceres & Vesta
1 Ceres and 4 Vesta shown to scale
Over the next six years other astronomers logged 2 Pallas, 3 Juno, and 4 Vesta. Ceres is the largest Main Belt asteroid with a diameter of around 940 km or about 27% the size of the moon. Though its surface gravity is only about 2.75% earth-normal, that’s enough to pull itself into a pretty good sphere as you can see here in the Hubble photo. Vesta is smaller but it’s the brightest asteroid as seen from the earth, at times marginally visible to the naked eye. After Vesta there was a 38-year slump, then Karl Ludwig Hencke discovered 5 Astraea and 6 Hebe in 1845 and ‘47.

The total number of asteroids on the books reached an even 100 with James Craig Watson’s discovery of Hekate in 1868, but the floodgates really opened with astrophotography pioneer Max Wolf toward the end of the century. Up until this time astronomers had to depend on their eyes and hand-drawn charts, but a photographic plate exposed an hour or more as the telescope followed the star field with a clock drive would reveal asteroids as tiny streaks. Wolf himself eventually discovered 248, from 323 Brucia (a Mars crosser) in 1891 to 1214 Richilde in 1932, the last year of his life. Among his most notable was 588 Achilles, the first of many Jupiter Trojans — asteroids that pace Jupiter within its orbit either 60 degrees ahead of it or 60 degrees behind.


Here are some of the best closeups available of asteroids and likely former asteroids with their sizes shown as a percentage of the moon’s. Hyperion, Phoebe, Amalthea, and Phobos are widely understood to be asteroids captured by Saturn, Jupiter, and Mars. All eight of these bodies are much smaller than Ceres and their surface gravities vary between 1/5000 and 1/250 of earth-normal.
HyperionPhoebeAmaltheaMathilde
Hyperion (Saturn)Phoebe (Saturn)Amalthea (Jupiter)253 Mathilde
270 km dia or 8%Lunar size214 km dia or 6.1%Lunar size167 km dia or 5%Lunar size52 km dia or 1.5%Lunar size
Cassini-Huygens/NASACassini-Huygens/NASAGalileo/NASANEAR - Shoemaker
Hyperion is icy and highly porous. Judging by the feeble pull it exerted on the Cassini probe it consists of about 40% empty space. Hyperion is also peculiar in that rather than rotating about a single axis it tumbles chaotically, so from its sky Saturn and the sun would swerve and rise and set in various directions. It reflects about 25% of the light that strikes it, similar in brightness to wet sand.

Phoebe is much darker, reflecting 6% or about the same as lampblack. It’s also about three times as dense as Hyperion. (Like the songbird it’s FEE-bee, though the original Greek was PHOY-bee.)

Edward Barnard, after whom Barnard’s Star is named, discovered Amalthea in 1892. This was the first Jovian satellite to be discovered after Galileo Galilei’s original four in 1609. Odds are Amalthea’s colors come from sulphur from neighboring Io’s many volcanos.

Ida & DactylPhobos433 Eros951 Gaspra
243 Ida + DactylPhobos (Mars)433 Eros951 Gaspra
27 km dia or 0.8%Lunar size22 km dia or 0.6%Lunar size18 km dia or 0.5%Lunar size12 km dia or 0.35%Lunar size
Galileo/NASAHiRISE/NASANEAR - ShoemakerGalileo/NASA
Ida was the first asteroid found to have a moon when the Galileo probe flew past it in 1993. It now appears that such a thing is quite common. In the case of Ida, its moon Dactyl (the dot of light on the right) orbits once every 37 hours at an average distance of 108 km (67 miles).

Phobos is the larger of Mars’s two moons and very dark like Phoebe. For years investigators puzzled over the parallel grooves on Phobos until they realized that they’re caused by rubble which blasted into orbit during impacts and then spiraled back down over millennia and skittered to a halt in the sand. Phobos itself is losing about 2 cm of altitude per year and will either strike Mars or shatter into a ring in 30 to 80 million years.

The NEAR-Shoemaker probe orbited boomerang-shaped Eros every whichway and came to rest on it on February 12, 2001. Eros belongs to the category known as Near-Earth Objects (NEOs) whose orbits intersect with the earth’s. Eros isn’t considered a danger, though in the late sixties tabloid-fueled rumors warned of an impending collision with it that would do us in.


Asteroids named after them
So far only 20485 (4%) of the numbered asteroids are named. Currently the highest-numbered named asteroid is 458063 Gustavomuler.

The asteroid with the longest name is 4015 Wilson-Harrington at 17 characters. Some of the runners-up at 16 characters are 1914 Hartbeespoortdam, 2039 Payne-Gaposchkin, 2072 Kosmodemyanskaya, 3087 Beatrice Tinsley… [skipping to the highest-numbered]… 274843 Mykhailopetrenko, 283990 Randallrosenfeld, 293707 Govoradloanatoly, and 316084 Mykolapokropyvny.

The shortest names are 85 Io (not to be confused with the Jovian moon Io), 954 Li, 1714 Sy, 2705 Wu, 3271 Ul, 6498 Ko, 16563 Ob, and 22260 Ur. First and last in the phonebook would currently be 20813 Aakashshah, named after a science fair-winning New Jersey medical student; and 2098 Zyskin, named after a professor at the Crimean Medical Institute. Someone even honored their keypad with 6600 Qwerty.

There’s 13681 Monty Python, as well as 9617 Grahamchapman, 9618 Johncleese, 9619 Terrygilliam, 9620 Ericidle, 9621 Michaelpalin, and 9622 Terryjones. You’ll also find 3834 Zappafrank (“Zappa” was taken and there were already 13 beginning with “Frank”) and 4147 Lennon, 4148 McCartney, 4149 Harrison, and 4150 Starr. 15845 Bambi and 16626 Thumper are named after the Disney characters; 4945 Roachapproach after New Age musician Steve Roach; and 3252 Johnny, 4238 Audrey, and 7707 Yes are named after Johnny Carson, Audrey Hepburn, and the British progressive rock band Yes. There’s no No, but a 2857 NOT, named after the Nordic Optical Telescope.

Herbert Hoover
Hoover
People don’t ordinarily pay for the privilege of naming an asteroid, but 250 Bettina stands as an exception. When discoverer Johann Palisa auctioned it off, the winning bidder at £50 (over $5000 in modern money) was Baron Albert Salomon “Salbert” von Rothschild. He named it after his wife, Bettina Caroline, who was also born a Rothschild. Palisa made minor history again years later when he named another one of his discoveries, 932 Hooveria, after future president Herbert Hoover in honor of the his work directing relief operations in Europe in the wake of World War I.

Proceed to “Asteroids” Part II: Big Red and other oddities, 723367 asteroids and counting, stunning riches


Space movie Martian curiosities Ten of the world’s
rarest gemstones
World’s rarest
metals
World’s rarest things
(and otherwise)

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