Asteroids and meteoroids are both fragments of rock

• Asteroids and meteoroids are both fragments of rock and are differentiated by size – bigger than 100 m with a mass over 10, 000 tons is an asteroid • The Asteroid Belt, It’s Not What You Think https: //www. youtube. com/watch? v=Drb. CAoiy. UNw

There are hundreds of thousands of asteroids • Most lie within the asteroid belt, about midway between Mars & Jupiter • • One known asteroid has a retrograde orbit – all others have prograde orbits • The Trojan asteroids lie 60 degrees in front or behind Jupiter in a delicate balance between Jupiter’s gravity and the sun’s

• Jupiter’s or Mars’ gravity might deflect an asteroid to a new orbit that crosses the Earth’s orbit http: //www. youtube. com/watch? v=x. Nx. YPpk 6 D 1 Q&sns=em 5 Ways to Stop a Killer Asteroid http: //youtu. be/cot 680 thsd. Q Gaia and the Killer Asteroids http: //youtu. be/Agdvt 9 M 3 NJA Bill Nye – Could we Stop an Asteroid

• Icarus 1566 (named because at periphelion it comes closer to the Sun than Mercury) and in June 1968 it came close enough to Earth (4 mill miles) to become the first minor planet to be tracked by radar; in June 2015 it came approx 8. 1 mill miles (passes Earth in June at 9, 19 or 28 yr cycles) http: //youtu. be/cot 680 thsd. Q Gaia and the Killer Asteroids http: //youtu. be/Agdvt 9 M 3 NJA Bill Nye – Could we Stop an Asteroid

• 2002 MN - 73 meter-sized asteroid that on June 14, 2002 missed the Earth by only 120, 700 km, about one third the distance to the Moon. • The close approach was second only to the Earth approach by the 10 meter-sized asteroid 1994 XM 1. • Discovered on June 17, 2002 three days after closest approach. • Its mass and relative velocity were in the same general range as the object ascribed to the Tunguska event of 1908, which leveled over 800 square miles (2, 100 km 2) of trees in Siberia.

Over 1400 of the Earth crossing asteroids are designated as potentially hazardous – large enough (larger than 140 m in diameter) and will come within 7. 5 million km of Earth…. their paths are on the next slide. • Between 2000 and 2010, about 200 that we know of passed within this distance, 2 within the orbit of the Moon. • Our closest predicted miss in the next century is Apophis, a 350 m asteroid, in April 2029, which should pass about 30, 000 km away. EEEEEEEK! •

• Every year about 3 asteroids do strike Earth – most are just too small to cause much damage, especially once they have gone through our atmosphere. ― Most strike uninhabited areas

• Several satellites have flown by and sent pictures back of asteroids over the years, usually on their way to other destinations. • Galileo passed by Gaspra on the way to Jupiter in 1991 and Ida in 1993 ▪ Ida has its own moon, Dactyl!

• Near Earth Asteroid Rendevous (NEAR) spacecraft was sent specifically to visit Eros, and stopped by Mathilde in 1997. • The decision was made for NEAR to land on Eros at the end of the mission in 2001. It was not made for this purpose, but succeeded and continued sending data for 2 weeks after the landing.

• Satellite Dawn began orbiting the 2 nd largest asteroid in the asteroid belt, Vesta, in July 2011. • Vesta has a series of deep troughs that girdle its equator.

• A dwarf planet is: • a celestial body orbiting a Sun that is massive enough to be rounded by its own gravity but which has not cleared its neighboring region of planetesimals and is not a satellite. • Dwarf planets can be found in the asteroid belt or trans-Neptunian, in the Kuiper belt.

Asteroid Belt Dwarf Planets • In July 2012, Dawn moved on toward the largest of all of the asteroids in the asteroid belt, the dwarf planet Ceres, which it reached in March 2015. ---Bright spots believed to be reflections from salt deposits https: //www. youtube. com/watch? v=dz. AOXde. JJb 0 ---From 240 miles away

Trans-Neptunian Dwarf Planets • Eris was believed to be the largest of the asteroids and is a dwarf planet, possibly up to 27% larger than Pluto, but New Horizons confirmed that Pluto is larger in 2015. • • Discovered in 2005 Has its own moon, Dysnomia

Trans-Neptunian Dwarf Planets • Eris was originally named 2003 UB 313, then was unofficially named Xena when it might become a planet. Upon the classification of a dwarf planet, it was officially called Eris after the goddess of strife and discord. Its moon, Dysnomia, is named after Eris' daughter, the goddess of lawlessness. (The actress that portrayed Xena on TV was is Lucy LAWLESS. ) • The discovery of Eris is directly responsible for Pluto no longer being a planet in 2006.

Trans-Neptunian Dwarf Planets • Haumea - is not spherical in shape, but it meets the definition of a dwarf planet by having reached hydrostatic equilibrium, which usually results in a spherical shape.

Trans-Neptunian Dwarf Planets • The provisional designation 2005 FY 9 was given to Makemake when the discovery was made public. Before that, the discovery team used the codename "Easterbunny" for the object, because of its discovery shortly after Easter. In July 2008, it was given the name of a creator deity. The name of Makemake, the creator of humanity and god of fertility in the mythos of the Rapanui, the native people of Easter Island, was chosen in part to preserve the object's connection with Easter.

Trans-Neptunian Dwarf Planets Pluto is a dwarf planet, demoted in 2006. • It is the largest of the dwarf planets, at 1, 473 miles (2, 370 km) in diameter, confirmed by the New Horizons mission in August of 2015. • • • http: //m. space. com/29957 -pluto-charon-fly-by-high-resolution-imagery-revealed-by-nasa video. html? cmpid=514630_20150715_49219956&adbid=10152944147996466&adbpl=fb &adbpr=17610706465 http: //solarsystem. nasa. gov/plutotime/

A comet is a ball of ice that travels on a highly elliptical orbit • Generally at least 1000 m in size • When it nears the sun it develops a tail and a coma, a gaseous cloud surrounding the nucleus • http: //youtu. be/OZlen. Avq. LCI Pan-STARRS from March 2013 Masses are believed to be similar in range to small asteroids

• The ion tail is formed by ionized atoms that have lost their electrons. It is highly influenced by the solar wind

• The dust tail is made up of fragments of dust that follow the orbit of the comet, giving it a curved shape Masses are believed to be similar in range to small asteroids

Tail always points away from the sun due to the solar wind – this was the reason that astronomers first began to infer the existence of the solar wind

• Many countries have sent missions to study comets, with varying success. • Stardust in 2004 got within 150 km of P/Wild 2 collecting particles in a aerogel dust collector and returned to Earth in 2006 with the materials ▪ First evidence for organic material apparently formed in deep space ▪ Presence of silicate materials that we had up until then believed could only form at high temps, which calls into question models of the formation of the solar system

• Deep Impact in 2005 launched a projectile into a comet, blasting gas and debris, video taping and collecting the gas that was ejected from the impact • Allowed a view of the internal composition of the nucleus of the comet • Confirmed the presence of water, ice and many organic molecules

Rosetta – ESA • Launched in 2004 to rendevous with Comet 67 P/Churyumov-Gerasimenko • Arrived at the comet • August 6, 2014 and began sending back pictures • No ice found on surface • Hydrogen and oxygen gas found at surface and in coma • Darker than charcoal black

Rosetta – ESA • Philae launched and landed from Rosetta on November 12, 2014 • Made last, futile attempt to contact Philae in Jan 2016 • FIRST EVER LANDING ON A COMET!!! • Strange sounds have been recorded from coming the comet by Rosetta– interactions from the solar wind and the coma of the comet - possibly material being shed from the comet becoming ionized by the plasma. LISTEN! • http: //www. iflscience. com/space/rosetta-s-comet-sounds-lot-predator

• The Kuiper belt is a region that lies outside of Neptune to about 100 times the distance of Earth from the Sun. Comets that originate in this area generally remain outside of the jovian planets, but may be kicked out of orbit by Neptune and sent in toward the Sun. • Called short-period comets, they have orbits of less than 200 years and stay within Pluto’s orbit • Tend to be prograde • Generally in same elliptical plane as the planets • Over 1000 known Kuiper belt objects, including Pluto

• The Oort Cloud is a spherical region of comets that surrounds the solar system out to more than 1, 000 times the distance between Pluto and the sun. • This was reasoned due to the fact that we observe only a tiny portion of the orbit of the long-period comets; so for every one we observe, there must be tons we don’t…. . thus there must be a huge cloud of comets far beyond the orbit of Pluto…. • First suggested in the 1950 s

• Most are long-period orbits, highly elliptical, going well past Pluto on their treks, taking hundreds of thousands of years or longer to complete an orbit.

• Halley’s Comet • Short period comet captured by Jupiter’s orbit • Returns about once every 76 years • Last here in 1985 -1986 • http: //youtu. be/C 8 z. V 1 xi. Gqf 4

A meteor is simply a piece of an asteroid or meteoroid or comet that interacts with or atmosphere…usually a meteoroid because they are so common • As the meteor moves through the atmosphere, the friction heats the molecules and atoms, exciting their electrons, which emit light when they return to ground state. •

Often the remains of broken up comets, therefore they often travel in meteoroid swarms & in nearly the same orbit as the parent comet resulting in yearly or twice yearly meteor showers • Meteor showers are named for their radiant, the constellation they appear to come from • • The Perseids seem to come out of the constellation Perseus every year in August

• When a meteor survives its trip through the atmosphere intact and hits the ground, you have a meteorite. • Smaller than about 1 m across and about 1 ton in mass usually burn up; larger make it to the surface The Barringer Crater meteoroid was about 50 m, around the size of the high school • The Tunguska explosion of 1908 was from a 30 m rock •

Ann Hodges – the only known human being ever hit by a meteorite – November 30, 1954 in Sylacauga, Alabama

https: //www. youtube. com/watc h? v=1 kv. Hl 5 Qcnzc https: //www. youtube. com/wat ch? v=p. FBtf. R 54 Svk https: //www. youtube. com /watch? v=w. Z 2 XXa 5 o. Fhw This is a piece of meteor 2011 EO 40 that exploded about 25 miles above Chelyabinsk, Russia, early in the morning on February 15, 2013. The power of the blast is estimated at over 20 x the strength of the atomic bomb dropped on Hiroshima This piece, recovered from Lake Chebarkul in Oct 2013, weighs at least 1257 lbs