Astronomy Club Presentation

8/7/2019 Astronomy Club Presentation

1/16

MeteoroidPREPARED BY:

Mohd ZakwanAamirul Ashraf


2/16

What Is Meteoroid?

Meteor

Fireball

BolideMeteoric dust

Meteorite

y A meteoroid is a sand- to boulder-sized particle of

debris in the Solar System

y

Meteoroid is also known as:


3/16

Meteor

yAmeteor is the visible streak of light that occurswhen a meteoroid enters the Earth's atmosphere

y Meteors typically occur in the mesosphere, and mostrange in altitude from 75 km to 100 km.

y Millions of meteors occur in the Earth's atmosphereevery day.

y Many meteors appearing seconds or minutes apart arecalled a meteor shower.


4/16

FireballyA fireball is a brighter-than-usual meteor.

yA fireball also defines as a meteor that would have amagnitude of -3 or brighter if seen at zenith.

* zenith is the direction pointing directly "above"a particular location


5/16

Bolidey There is no official definition of bolide and generally

considers the term synonymous with fireball.

y The bolide term is generally used for fireballsreaching magnitude -14 or brighter.

y If the magnitude of a bolide reaches -17 or brighter it isknown as a superbolide


6/16


7/16

Impact cratersy When large meteoroid strike the earth, they produce

an impact crater or impact basin.

y Impact craters are bowl-shaped depressions thatmeasure up to about 10 miles (25 kilometers) indiameter. They have shallow, f lat floors and upliftedcenters.


8/16

Meteorite classification

St nym t rit s

St ny-ir nm t rit s

Ir n m t rit s


9/16

Meteoric dust

y Most meteoroids are destroyed when they enter theatmosphere

y The left-over debris is called meteoric dust or justmeteor dust.

y Meteor dust particles can persist in the atmospherefor up to several months.

y These particles might affect climate, both by scattering

electromagnetic radiation and by catalyzing chemicalreactions in the upper atmosphere.


10/16

Ionization trailsy During the entry of a meteoroid into the upper

atmosphere, an ionization trail is created.

y

The molecules in the upper atmosphere are ionized by thepassage of the meteor. Such ionization trails can last up to45 minutes at a time.

y Small, sand-grain sized meteoroids are entering theatmosphere constantly, essentially every few seconds in any

given region of the atmosphere, and thus ionization trailscan be found in the upper atmosphere more or lesscontinuously. When radio waves are bounced off thesetrails, it is called meteor burst communications.


11/16

The Coloury The visible light produced by a meteor may take on

various hues, depending on the chemical compositionof the meteoroid, and its speed through theatmosphere.

yAs layers of the meteoroid are stripped off and ionized,the colour of the light emitted may change accordingto the layering of minerals.

y Some of the possible colours and the compoundsresponsible for them are: orange/yellow (sodium);

yellow (iron); blue/green (copper); lilac (potassium);and red (silicate).


12/16

Notable meteorite

yPEEKSKILL METEORITE

The Peekskill meteorite broke up over the United States on

October 9, 1992, an event witnessed by thousands acrossthe East Coast.The meteorite broke up over Kentucky and

damaged a parked Chevrolet Malibu in Peekskill, NewYork on impact. Major cities like Pittsburgh witnessed the

bright meteorite. The meteorite travelled northeast andhad a pronounced greenish colour. The meteorite has beencaptured on 16 different videos and remains as one of the

most famous meteorite sightings.


13/16

Peekskill Meteorite


14/16

References : Internet

Wikipedia

http://en.wikipedia.org/wiki/Meteoritehttp://en.wikipedia.org/wiki/Meteor_shower

http://en.wikipedia.org/wiki/meteoroid

y NASA

www.nasa.gov/worldbook/meteor_worldbook.html


15/16

Books

y AstronomyToday

-by Chaisson McMillan

y Pathways to Astronomy-by Stephen E. Schneider & Thomas T. Arny

y Astronomy : A Beginners Guide to the Universe

-by Chaisson McMillan


16/16

Documents

Astronomy Club Presentation