Solar System Astronomy 29:50

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Solar System Astronomy

• Asteroids

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Discovery of First AsteroidCeres (1801)

• Discovered 20 yrs after Herschels discovery of
  Uranus by G. Piazzi (Palermo, Sicily)
• Predicted by Bodes Law (planet spacing 0.4
  0.3 2n)
• Found accidentally, after 40 days of observations
  (looking for comets)
• Ceres is latin for harvest, hence cereal.
• Diameter 925km, mass 1 that of Moon.

Father Giuseppe Piazzi of Palermo, the
discoverer of Ceres
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Finding an asteroid by motion with respect to
fixed stars
Asteroid 5 (Astraea) observed 31 Oct 2002 at Iowa
Robotic Observatory
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Asteroid Properties Orbits
Starry Night Go/Inner Solar System
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These are regions where an object is perturbed by
Jupiters gravity its orbital period would be a
simple fraction of that of Jupiter. An object in
such an orbit is very likely to be accelerated by
Jupiter into a different orbit.
Jupiter
NEAs (Near Earth Asteroids)
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Main-belt and Trojan Asteroids
Main belt
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Asteroid Types

• C-type, includes more than 75 of known
  asteroids extremely dark (albedo 0.03) similar
  to carbonaceous chondrite meteorites
  approximately the same chemical composition as
  the Sun minus hydrogen, helium and other
  volatiles
• S-type, (17) relatively bright (albedo
  .10-.22) metallic nickel-iron mixed with iron-
  and magnesium-silicates
• M-type, (8) Most of the rest bright (albedo
  0.10- 0 .18) pure nickel-iron.

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Asteroid Visits 951 Gaspra

• Galileo flyby 1991 closest approach 1,600 km
  (1,000 mi)
• Discovered in 1916, named for a Black Sea resort
  frequented by Tolstoy, Gorky.
• Size 19km x11 km x10 km
• S-type asteroid (20 albedo)
• Small craters gt relatively recent origin
  (breakup of larger asteroid?)

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Asteroid Visits 243 Ida (Dactyl)

• Galileo flyby 1993 closest approach 1,600 km
  (1,000 mi)
• Discovered in 1810. Ida was a nymph who raised
  the infant Zeus.
• Size 56 km x 24 km x 21km
• S-type asteroid (20 albedo)
• Has small satellite! Dactyl (2 km x 1km x 1km)

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Asteroid Visits Eros

• NEAR spacecraft flyby and landing on Feb 12,
  2001!
• Discovered in 1916, named for a Black Sea resort
  frequented by Tolstoy, Gorky.
• Size 19km x11 km x10 km
• S-type asteroid (20 albedo)
• Small craters gt relatively recent origin
  (breakup of larger asteroid?)

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433 Eros
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Eros/ NEAR spacecraft landingSpacecraft
successfully landed, took several pictures of
surface
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NEAR Instruments