Northeastern Illinois University Asteroids, Comets & Dwarf Planets Greg Anderson Department of Physics & Astronomy Northeastern Illinois University Fall 2019 c 2012-2019G. Anderson Universe: Past, Present & Future – slide 1 / 104 Northeastern Illinois Overview University Asteroids Meteors & Meteorites Comets TNOs Impacts Review c 2012-2019G. Anderson Universe: Past, Present & Future – slide 2 / 104 Asteroids & Comets b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b Kuiperb Belt b b b b b b Asteroidb b Belt b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b Oort Cloudb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b Northeastern Illinois Zodiacal Light University Zodiacal light: faint glow near the ecliptic from sunlight scattered off the zodiacal cloud, a pancake shaped cloud of interplanetary dust. Origin: Continually replenished by comet disintegration & asteroid collisions. Recent estimates: 85% from Jupiter family comets. Size 10 − 300 µm c 2012-2019G. Anderson Universe: Past, Present & Future – slide 4 / 104 Zodiacal light scattered from the Zodiacal Cloud c G.Anderson LowerCanyonsoftheRioGrande Zodiacal light scattered from the Zodiacal Cloud c G.Anderson LowerCanyonsoftheRioGrande Northeastern Illinois University Asteroids & Comets Zodiacal Light Zodiacal Light Asteroids Asteroid Facts Discovering Missions Largest Ceres & Vesta Q: Ceres? Asteroids Asteroids Main Belt Main Belt Eros from NEAR Q: Shape Albedo Spectral Types asteroid orbits Histogram vs a Scatter i vs a Asteroid Families asteroid orbits Trojans Q: Trojans Origin Theories Kirkwood Gaps Migrations c 2012-2019G. Anderson Universe: Past, Present & Future – slide 6 / 104 Q: Gaps Northeastern Illinois Asteroid Facts University Relatively small, rocky objects orbit- ing the Sun. • Leftover rocky planetesimals • Majority between Mars and Jupiter • Total mass ≪ MMoon • Largest Ceres, d ≈ 950 km • 1.1 − 1.9 million with d> 1 km. • > 400, 000 cataloged Vesta c 2012-2019G. Anderson Universe: Past, Present & Future – slide 7 / 104 Northeastern Illinois Discovering Asteroids University Time exposures with false color paral- lax: from Paranal and from La Silla. c 2012-2019G. Anderson Universe: Past, Present & Future – slide 8 / 104 Northeastern Illinois Asteroid Missions to Asteroids University • DAWN (NASA) 2007–, Ceres (2015), Vesta (2011) • Rosetta (ESA) 2004–, Comet Churyumov-Gerasimenko, Asteroids 21 & 2867 • Hayabusa (JAXA) 2003-2010, sampled asteroid Itokawa and returned samples to earth • Genesis (NASA) 2001– • Stardust - NASA • Deep Space 1 - NASA • Cassini - NASA/ESA • NASA Near Earth Asteroid Rendezvous (NEAR-Shoemaker) • Galileo - NASA c 2012-2019G. Anderson Universe: Past, Present & Future – slide 9 / 104 Northeastern Illinois Largest Asteroids (by Diameter) University Name Discovered a (AU) d (km) Class 1 Ceres 1801 2.77 975 C 4 Vesta 1807 2.36 525 V 2 Pallas 1802 2.77 512 B 10 Hygeia 1849 3.14 431 C 704 Interamnia 1910 3.06 326 C 52 Europa 1858 3.10 315 C 511 Davida 1903 3.18 289 C 87 Sylvia 1866 3.49 286 X 65 Cybele 1861 3.44 273 C 15 Eunomia 1851 2.64 268 S 1 The 4 largest asteroids contain over 2 the mass of the asteroid belt. c 2012-2019G. Anderson Universe: Past, Present & Future – slide 10 / 104 Northeastern Illinois Asteroids Ceres & Vesta University Ceres, The Moon, & Earth Vesta, Ceres & The Moon • Ceres is large enough to be classified as a dwarf planet. • Ceres and Vesta were large enough to undergo differentiation. c 2012-2019G. Anderson Universe: Past, Present & Future – slide 11 / 104 Northeastern Illinois How big is Ceres? University The largest asteroid, Ceres, was also the first asteroid to be discovered (1801). What is the approximate diameter of Ceres? A) 1 km B) 10 km C) 100 km D) 1,000 km E) 10,000 km c 2012-2019G. Anderson Universe: Past, Present & Future – slide 12 / 104 Northeastern Illinois How big is Ceres? University The largest asteroid, Ceres, was also the first asteroid to be discovered (1801). What is the approximate diameter of Ceres? A) 1 km B) 10 km C) 100 km D) 1,000 km E) 10,000 km c 2012-2019G.