Asteroids Comets Meteors Grab a Book and go

Asteroids, Comets & Meteors…. Grab a Book and go learn about them!

Comparing A, C, M • • How does it form, origin Composition Size Orbit Found / located where How are they seen in the sky Glow? Reflective? Burn? Best known example Asteroid Comet Meteor

The Solar System Leftovers • ALL are Leftovers from the formation of the Solar System 4. 6 bya went into either the – Asteroid belt – Kuiper Belt – Oort Cloud • Cosmic “debris” • Range in size from mountain sized chunks to dust

The Asteroid Belt • Between Mars an Jupiter • Astronomers have cataloged more than 500, 000 asteroids • in near circular orbits. (eccentricity close to 0) • All orbit in counter-clockwise. • The tilt orbits - more exaggerated than the planets.

Asteroids • Too small to be classified as planets, (100 m – 100 km) • Gravitational pull of Jupiter and Mars didn’t allow for material to form a planet. • About half the known asteroids are probably ‘dead’ comets • Also classified by albedo – How well their surface reflects sunlight and we can see them

• Way out beyond Neptune • “outer asteroid belt” • Consists of mostly ICY, rocky objects • Very elliptical orbits

Large Asteroid or Dwarf Planet? Ceres • 950 km wide Pluto • 2300 km wide – (590 miles) – (1430 miles) In 2006, Ceres was upgraded from an asteroid a ‘dwarf planet’ – A the same time, Pluto was downgraded from a planet to a dwarf planet

Comets • Greek for “long hair” • Called ‘dirty snowballs’ because of their composition • A mixture of ice, frozen gas, and dust • Material that didn’t get incorporated into planets during solar system formation

Comets, cont. • Most comets live in a cloud beyond Pluto called the Oort Cloud • 1 -10 km in size • Comets have HIGHLY elliptical orbits, - some comets take millions of years to complete one orbit.

Parts of a Comet

The comets ion tail is always pointed AWAY from the Sun. The dust tail curves and lags behind the ion tail. Comets can be seen for many days.

Meteors • Bits of the solar system that have fallen to the Earth – Most come from asteroids – Some come from left-behind comet debris

Catch a Falling Star • Meteor is the term for the sight of the streak of light caused by a meteoroid –which is the term for the small (less than 100 m) rocky object that enters the atmosphere. • Most are completely burned up, but some do get through to strike Earth = meteorites

Meteor Showers (a. k. a. Comet showers) • Whenever a COMET makes its nearest approach to the Sun, some pieces break off. • The larger fragments take up orbits with the parent comet, but some fall behind, so that the comet’s path is eventually filled with the tiny micrometeoroids.

Meteor Showers • Periodically, Earth’s orbit intersects with a cluster of such micrometeoroids, resulting in a meteor shower. • Meteor showers associated with certain comets occur with high regularity. • They are named after the constellation from which their streaks appear to radiate.

Name of the Meteor Shower Max. Activity Est. Hourly Count Parent Comet Quadrantid Jan. 3 50 Unknown Beta Taurid June 30 25 Encke Perseid Aug. 12 50+ 1862 III Draconid Oct. 8 -9 500+ Giacobini -Zimmer Orionid Oct. 20 25 Halley Leonid Nov. 1617 10* 1866 I Geminid Dec. 1117 50 -75 3200 Phaeton

Asteroids, meteor composition. • Three types: – Carbon, Silica (rocky), Metallic (iron and nickel) - Carbon meteorites contain water and organic molecules, amino acids – the building blocks of life!

Scientists believe that the water in the earths hydrosphere arrived here in icy meteorites over millions of years of bombardment

Why do scientists study meteorites? ? • Most meteorites are similar to rocks on Earth, • But a few have rare minerals only found in meteorites. • Meteorites represent many different rock types and probably come from different bodies in the solar system. • They are the oldest rocks in the solar system and are used to date the beginning of the solar system. • The early solar system had very different composition, temperatures and pressures

Could it Happen? • Nearly 100 asteroids have been identified to have eccentric orbits that cross that of Earth. • The possibility of a collision is real. • Project NEAT (Near Earth Asteroid Tracking)

Asteroids, Comets, Meteoroids As many as 1000 NEO’s may be large enough to threaten the Earth should an impact occur. http: //neo. jpl. nasa. gov/orbits/

What killed the dinosaurs? • An asteroid, a meteor or a comet?

Bellwork: matching a. asteroid b. meteoroid 1. Rank from smallest to largest. c. comet M C A M C 2. Which are located in the: asteroid belt, Oort Cloud Asteroids comets 3. Which “glow” with burning gases? 4. Which are rocky? A M 5. Very elliptical and tilted orbit? comets