Smaller Bodies of the Solar System Chapter 2 continued

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Betty Murphy
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1 Smaller Bodies of the Solar System Chapter 2 continued Small, rocky (sometimes metallic) bodies with no atmospheres. or planetoids 100,000 numbered and 12,000 named km in size most are small ~ 1 million Asteroids Divided into classes based upon orbit and spectral class. Orbits of Asteroids a vast ring of hundreds of thousands of rocky objects circling the orbits of and 2 to 4 AU from the Sun Orbits of Asteroids (NEA s) within 1.3 AU of the Sun Three categories: Armors Apollos Atens Three Categories of NEA s Amors cross Mars' orbit but do not quite cross Earth's orbit. More than 1,500 Amors are known. Eros, which was visited by the Near Earth Asteroid Rendezvous (NEAR) spacecraft, is an Amor. Three Categories of NEA s Apollos Earth orbit-crossing asteroids orbit periods longer than one year

2 More than 1,700 Geographos is an Apollo. Three Categories of NEA s Atens cross Earth's orbit orbital period less than 1 year. Roughly 300 Atens are known Spectral class of Asteroids C-type (Carbonaceous) > 75% of all asteroids Very dark Outer region of Main Belt S-type (Silicaceous) About 17% Fairly bright objects Inner Main Belt M-type (Metallic) Fairly bright Metallic iron Mid Main Belt Asteroid Ida with moon Dactyl in space that encounter Earth s atmosphere and. Meteor Shower occurs when Earth's orbit intersects the orbit of a meteor stream Annual Meteor Showers

3 Occur when earth s orbit passes through trail of debris of comet as it orbits Sun Meteoroids that Three Categories of Meteorites Same minerals as rocks on Earth Primarily iron and nickel Half as abundant as stony meteorites Easier to find Stony-iron mixtures of iron and stony Stony and Iron Meteorites Meteorites Hitting Earth Several hundred tons hit the atmosphere every day Most are small a few milligrams Largest 70 tons Grootfontein in southwest Africa Meteorites hitting Earth Average speed entering atmosphere mi/hr decelerate to ~125 mi/hr Large meteors are slowed very little more than 200 tons Winslow, Iron meteor feet in diameter Crater is 3900 feet in diameter and 650 feet deep

4 120 impact craters on Earth Tunguska Event natural explosion that occurred at Tunguska River in what is now Evenkia, Siberia, at 7:17 AM on June 30, 1908 Tunguska Event Airburst of meteor 4 to 6 miles above Earth s surface 10 to 15 megaton blast Impact heard in London No crater was found Tunguska Event Felled an estimated 60 million trees over 800 square miles Before After 2004 XP14 269,000 miles (slightly farther than the Moon) Quarter to half-mile wide Class: Apollo Mixture of ices (both water and frozen gases) and dust (KNOW) highly eccentric orbits which take them far beyond the orbit of Pluto Known since antiquity Comet Halley China (240 B.C.) 878 catalogued 184 periodic comets orbits less than 200 years Composition Small, solid body made of water, CO2, methane, rock, and dust

5 Deep Impact Impacted comet 9P/Tempel July 4, 2005 solid and stable mostly ice and gas some dust only a few miles in diameter Comet Halley 3 miles in diameter 76 year period Parts of a Comet dense cloud of water, carbon dioxide, and other gases sublimed off nucleus (KNOW) Up to 250,000 miles in diameter begins to form at 5 A.U. points from solar wind and radiation push particles and ionize gases Tens of millions of km long Path of a Comet Evolutionists define comets as primordial Existing at or from the beginning, primeval; original, fundamental What happens to comets when they orbit the sun? much of its Typical max age = 10,000 years Shorter period comets have been observed to dim remarkably over the years

6 Gives support to a young world according to creationists ,000 years old Can change orbit Gravitational interaction with planets Can be completely destroyed Shoemaker-Levi collided with Jupiter in 1994 Can breakup What is the Oort Cloud? a cloud supposed to exist at the outer reaches of our solar system from which come. The Theory of the Oort Cloud Evolutionists Oort Cloud comets come from an unobserved spherical 'Oort cloud' well beyond the orbit of Pluto computer simulations have clearly shown that short-period comets cannot originate from the cloud, gravitational interactions with infrequently passing stars often knock comets into the solar system Not substantiated either by observations or realistic calculations interactions with planets slow down the incoming comets often enough to account for the hundreds of comets observed Not substantiated either by observations or realistic calculations Problems for the Oort Cloud None of these assumptions has been substantiated either by observations or realistic calculations The Oort cloud has never been observed and there is no evidence it even exists!!! (KNOW)

7 What is the? massive flattened disc of billions of supposedly left over from the formation of the solar system proposed as source for long-period comets and a replenisher of the Oort Cloud. beyond Neptune (extending from 30 AU out to around 100 AU). occasionally disturbed by gravitational interactions these objects are sent hurtling into the inner solar system to become short-period comets Kuiper Belt Objects Appear to be a number of small objects beyond the orbit of Neptune (KBO s) Problem with KBO s Much larger than comet nuclei Several are binary They orbit each other Statistically difficult for two orbiting masses to be formed randomly No one can clearly identify a single image as a comet nucleus A major problem is that the imaging system is subject to random signals, called noise, that mimic these faint points, so from a single image one cannot have any confidence that any particular point of light is real.

1star 1 star 9 8 planets 63 (major) moons asteroids, comets, meteoroids

The Solar System 1star 1 star 9 8 planets 63 (major) moons asteroids, comets, meteoroids The distances to planets are known from Kepler s Laws (once calibrated with radar ranging to Venus) How are planet