IMPACT Pre-Lab Notes Write each question as it appears. Then write complete answers based on the following slides..

QUESTION #1: What things can hit the Earth … or other bodies for that matter?

Well, to start with chunks of dust, rocks and debris can fall into earth’s atmosphere as METEORS.

Search the Web to find out how many meteors enter earth’s atmosphere each day? Write it down.

Bigger chunks of wandering rocks, ASTEROIDS, pose a serious threat.

Finally, chunks of rock and ice called COMETS could hit earth as they travel through the inner solar system!

QUESTION #2: What are NEO’s?

NEO stands for Near Earth Object.

An NEO can be any comet or asteroid whose orbit intersects earth’s orbit and has some potential of impacting earth in the future.

A government agency at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California searches for and tracks NEOs.

Do a web search and find out: A)How many NEOs are currently being tracked. B)How many NEOs are estimated to exist. C)Describe the NEO that currently poses the biggest threat.

QUESTION #3: Where do these objects come from?

First of all, you have to realize that there is a lot more to the solar system than 8 (or 9) planets.

There exists a spherical region hosting perhaps millions of icy COMETS called the OORT CLOUD. Oort Cloud

Another region hosting comets is a halo of material at the distance of Pluto’s orbit called the KUIPER BELT. Kuiper Belt

ASTEROIDS originate from the asteroid belt – a ring of material between the orbits of Mars and Jupiter.. Asteroid Belt

Be sure to include a labeled sketch of all these regions in your notes. Asteroid Belt Oort Cloud Kuiper Belt

QUESTION #4: What factors are involved in the size and shape of impact craters?

IMPACT CRATERS

All of these variables can contribute to cratering: The speed (velocity) of the collision The mass of the impactor. The impactor material The surface material.

QUESTION #5: What things could you learn by looking at impact craters on planets and moons?

Energy of the collision. Size/Speed of impactors. Relative ages of planets and moons. History of that body. History of the solar system!

QUESTION #5: Describe three notable Earth impact craters?

Three Notable Earth Impacts 1)Barringer Crater Arizona –About 1 mile diameter –50,000 yrs old (Pleistocene) –Nickel-Iron impactor about 80 ft. across. –Speed estimate: 29,000-45,000 mph (8 to 12 miles per second)

Three Notable Earth Impacts 2) Chicxulub crater, Yucatan PeninsulaChicxulub –Cretaceous/Tertiary boundary (K-T) - the event that we think caused the extinction of the dinosaurs (65 MYO). –Impactor the size of a small city (10 km) –Giant Tsunamis (100s to a couple thousand feet tall), global earthquakes

2) Chicxulub crater, Yucatan PeninsulaChicxulub –Yucatan solid rock turns to “jello” –Central uplift (2-3 x Everest height) then collapses forming rings.

Three Notable Earth Impacts 3) Tunguska, Siberia On the date of June 30th, 1908, at about a quarter after 7:00 a.m., a very mysterious explosion occurred in the skies over Tunguska, Siberia, located in Russia. This explosion happened at anywhere between six-to-eight kilometers from ground zero, and the resultant action in this was to lay waste to a vast region of pine forest of 2,150 square kilometers, felling more than 60 million trees.

View from Kirensk, 400 km away, two seconds before the explosion.

60 Km from Ground Zero

15 km. from ground zero. A few minutes after the explosion

QUESTION #6: What are your chances of getting hit?

What are the Chances? Craters 40km diameter or more are likely to be caused by 2km diameter asteroids or comets. Such impacts would probably result in severe global climate disruption but it takes an asteroid/comet 10km or larger to cause mass extinctions. It is estimated that such impacts occur, on average, once every 50 to 100 million years.Such impacts would probably result in severe global climate disruption but it takes an asteroid/comet 10km or larger to cause mass extinctions

Chances Cont. More than 160 asteroids have been classified as "potentially hazardous" by the scientists who track them. Some of these, whose orbits come close enough to Earth, could potentially be perturbed in the distant future and sent on a collision course with our planet. Your chance of getting hit in your lifetime is (1-20,000.) Compare this with- car accident (1-200) tornados, food poisoning, rattlesnake bites (1-60,000) For every asteroid that passes close to earth several go unnoticed. For instance, on 1/7/04 a asteroid the size of three football fields came within two lunar distances.

Chances cont. Smaller asteroids that are believed to strike Earth every 1,000 to 10,000 years could destroy a city or cause devastating tsunamis. A near earth Object (NEO) does not need to be large to devastate. One the size of a small garage would annihilate a large city. One big enough to leave a 10km crater, still nowhere near the size of the biggest (there is a 300km crater on Earth), would have the destructive force of every one of the world's 10,000 nuclear warheads combined.

QUESTION #7: What are the features of typical impact craters? Sketch a crater and label the following features

Lunar Impact Crater Typical characteristics of a lunar impact crater are labeled on this photograph of Aristarchus, 42 im in diameter, located West of Mare Imbrium. Common definitions:

floor bowl shaped or flat, characteristically below surrounding ground level unless filled in with lava. ejecta blanket of material surrounding the crater that was excavated during the impact event. Ejecta becomes thinner away from the crater. raised rim rock thrown out of the crater and deposited as a ring-shaped pile of debris at the crater's edge during the explosion and excavation of an impact event. walls characteristically steep and may have giant stairs called terraces. rays bright streaks starting from a crater and extending away for great distances. See Copernicus crater for another example. central uplifts mountains formed because of the huge increase and rapid decrease in pressure during the impact event. They occur only in the center of craters that are larger than 40 km diameter. See Tycho crater for another example.

Meteor Composition Iron meteorite Iron 91% Nickel 8.5% Cobalt 0.6% Source: Encyclopedia Britannica Stony meteorite Oxygen 36% Iron 26% Silicon 18% Magnesium 14% Aluminum 1.5% Nickel 1.4% Calcium 1.3% Earth's crust Oxygen 49% Silicon 26% Aluminum 7.5% Iron 4.7% Calcium 3.4% Sodium 2.6% Potassium 2.4% Magnesium 1.9%