Remnants of Rock and Ice Asteroids Meteoroids meteorites

Remnants of Rock and Ice • Asteroids • Meteoroids (meteorites, meteor) • Comets

Remnants of the Solar Nebula • Small bodies remain virtually _____ unchanged since their formation _____ years ago 4. 5 billion • They carry history of the Solar system in their ______, and _______. compositions locations numbers Asteroid means ____, a rocky leftover starlike space Meteoroid – small rocky material in _____ in the atmosphere Meteor – ________ (falling star) Meteorite – any piece of rock than fell to the ______ from the sky ground Comet means _____ (Greek), an icy leftover hair

Asteroids (minor planets) • Most abundant _______ the orbits between of Mars and Jupiter • Largest is ______, Ceres 800 km diameter • Most are much Smaller, irregular ________

Ceres

Asteroid Eros

Asteroids (minor planets)

Evolution of the Belt Early in the history of the Solar system, the belt contained enough planetesimals to form a planet. Gravitational tugs from _______ created the Jupiter gaps. Two stable zones along Jupiter’s orbit host two families of asteroids (_______). Trojans

Jupiter’s Trojan Asteroids

Meteorites rock Meteorites are pieces of _____ that fell from the sky. fireballs Seen as _______ (sometimes with sound) May cause damage, but most fall into oceans ______ Earth Pelted with Ashes from Nearby Supernova Explosions

Meteorites Meteor showers – result of the Earth’s ____________ passing through a comet orbit Meteors are ______ of comet dust single pieces ______ meteoroids enter Earth’s 25 million atmosphere every day Meteor showers get their names after _______ from which they constellations appear to radiate

Meteor Showers (These occur when earth passes through cloud of debris along a comet’s orbit. )

Ionized Trail Generation by Meteor Crossing Eastern US, 1992

The Origin of Meteorites ____ meteorites may be either rocky or Primitive carbon-rich ______ meteorites can be removed Processed from the surface of a planet by an impact. There are meteorites from Moon and Mars found on Earth.

http: //www. youtube. com/watch? v=cajf. Ftu_ QPA&feature=related http: //www. youtube. com/watch? v=dpm. Xy. Jr s 7 i. U https: //www. youtube. com/watch? feature= player_embedded&v=OFDr. He 7 Iz. A 8 November 2 nd, 2015 https: //www. youtube. com/watch? v=7 d. CT 407 AM NE November 4 th, 2015 http: //www. msn. com/enus/video/downtime/extremely-close-meteor -strike-caught-on-film/vi-BBp. G 13 b Feb. 18, 2016

Primitive Meteorites

Processed Meteorites

Giant meteor hits Earth. Why no one saw it. The largest meteor since the 2013 impact in Chelyabinsk, Russia, hit Earth on Feb. 6, 2016. The fireball fell into the ocean off the coast of Brazil and released energy roughly equivalent to 13, 000 tons of TNT. This is significantly less than the Chelyabinsk impact, with the equivalent of 500, 000 tons of TNT, but it was at least 26 times as powerful as any of the three impacts NASA reported in February 2015.

rock and • Chunks of ____ ___ in highly ice eccentric orbits • Near sun, ice sublimates _____ to “tail” produce _____ • A couple have been visited by robotic craft Comets

Comet Structure Comets are basically _______ where dirty snowballs ice mixes with rocky dust. Their mean size is a _________. few kilometers across The comet body is called _______. nucleus coma Sublimating ices create _____. A tail pointing _____ from the Sun appears. away There are ___ tails: plasma tail and dust tail. two

Comets

Comet Orbits

Comets contain information about the _____ solar system outer Most of them visit the inner part only once, a few are regular guests One of the most famous comets is _______ Halley’s _____. It was discovered by Edmund Halley comet in 1682. Its orbital period is 76 years. The last appearance in 1986. (2062)

Halley’s Comet

Comet Hale-Bopp

Comet Shoemaker-Levy 9

Comet ISON Scott Ferguson captured this image of Comet ISON on Oct. 27 while at a friend's private observatory, Northwest Florida Observatory.

• Discovered in September 2012 by two Russian amateur astronomers • Thought to be making its maiden voyage to the inner solar system from the Oort Cloud.

• ISON made its closest approach to the Sun on Nov. 28, 2013 when it came within a mere 730, 000 miles (1. 2 million kilometers) of the solar surface. • ISON broke up after passing the Sun and was relatively underwhelming.

Comet 67 P/ Churyumov-Gerasimenko • A European robot probe Philea, released from the Rosetta spacecraft, has made the first, historic landing on a comet.

Philae's landing site is on the head of the 4 km-wide rubberduckshaped comet

Leg of Lander Nucleus

Photo from Philae shows the surface during the lander's approach

Earth impacts • Do we ever get hit? • Yes! The questions are when and by what? size • Classify events by ____ –Small –Medium –Large

Impacts The ______ the ____, the _____ larger impactor more rare the impact In 1908, an unusual explosion occurred in Siberia ____. Arizona Meteor crater in _______ formed 50, 000 years ago. A ______ occurred ___ million years larger impactor 65 ago perhaps caused the _________. dinosaur extinction

Earth impacts: small less 50 m across • Small: _____ than ______ at top of atmosphere all the time – Happening _______ – Will burn up or break up in the _____ atmosphere – Most are very tiny (‘pea’ sized) Shooting stars – Meteors! (“_______”, “Falling stars”) • Can see 3 - 5 per hour on a typical night • 25 million every day! • 100 tons per day

© AP Photo: Yekaterina Pustynnikova, Chelyabinsk. ru http: //abclocal. go. com/wls/story? id=8997035

• This meteoroid was only 62 feet wide. • Traveling at 42, 000 mph. • Burst over Chelyabinsk in February with the force of 40 Hiroshima-type atom bombs. • It released a shock wave that shattered thousands of windows and injured more than 1, 600 people. • Its flash was bright enough to temporarily blind 70 people and cause dozens of skinpeeling sunburns just after dawn in icy Russia.

http: //www. redorbit. com/news/video/space_2/1112977820/russianmeteorite-fragment-ural-mountains-lakebed-101713/

Earth impacts: medium • Medium: ________ at top of 50 m – 1 km across atmosphere – Only ~ _________ one every century or millennium ______ – Causes “severe local damage” – Two great examples from ‘recent’ history

Earth impacts: medium • The Tunguska event - Siberia, Russia – Happened in 1908 Flattened – _____ a forest – Knocked people over _______ (140 200 km miles) away No crater – _____ (exploded just above ground) • The impactor? – A stony meteorite (? ) Size: 30 m

The Tunguska event

The Tunguska event

Earth impacts: medium • The Berringer Crater, in Arizona –Happened _______ 50, 000 years ago –The crater: • _____ m across 1, 200 • ____ m deep

Earth impacts: medium • The impactor? –An iron meteorite 100 m across –______ (50 m on impact) –Going _______ mph! 40, 000 –Explosion = ______ of TNT 20 million tons • A moderate atomic bomb • 2 Mt. Saint Helens

The Berringer crater, Arizona

Earth impacts: large more than 1 km across • Large: __________ at top of atmosphere One –____ every ________ few million years –Severe global effects –More than __ km can cause 2 mass extinction –Most recent: 65 million years ago

Earth impacts: large • The K/T extinction event – Some history… • ‘K/T’ = ‘Cretaceous / Tertiary’ • 60 % of all species on Earth disappeared, including the dinosaurs • One explanation (there are several): Earth was hit by a large impactor

Earth impacts: large • The K/T extinction event –Evidence for an impact: Iridium • _______ found at that geologic level • A crater near the _____, Yucatan in Mexico

The K/T extinction event

Earth impacts: large • The K/T extinction event – The impactor: Asteroid • Probably an ____ • Size: ~ ______ 10 km across • Energy released: 100 –____ million tons of TNT –__ million atomic bombs 5 10 –___ million Mt. Saint Helens

How often is there an impacted?

How often do impacts occur?

How To Avoid Impacts? Bombs - Detonate close - push object away Lasers - Pulses to decrease mass, slows Solar collectors -Vaporize to decrease mass Kinetic kill – Space speed bumps - slows Dock & push – Space craft pushes object Solar sails – Use solar wind to push object Gravity tractor – position craft close

http: //astro 1. panet. utoledo. edu/~anatoly/astr 1010/materials/324, 41, Slide 41 http: //campus. pari. edu/sara/arecibo/presentations/fields/294, 13, Meteor Trail Recorded During Leonid Meteor Shower, 1998 http: //departments. weber. edu/physics/schroeder/astro/lectureslides/356, 8, Kuiper Belt objects (other stuff near Pluto) http: //www. phys-astro. sonoma. edu/people/faculty/carico/A 100/367, 2, Earth impacts