Comets and Their Significance In the past people dreaded comets as omens of human disasters such as wars or famines Today we know that comets are icy members of our solar system that have highly elliptical orbits ID: 490609
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Slide1
Comets, Meteors, and MeteoritesSlide2
Comets and Their Significance
In the past, people dreaded comets as omens of human disasters such as wars or famines.
Today we know that
comets are icy members of our solar system that have highly elliptical orbits. Comets follow the basic laws of physics and are not supernatural signs at all. Comets are important because they are made of the original material that made our whole solar system.Slide3
Comet Structure
Far from the Sun, comets just look like dirty snowballs.
As they near the Sun they heat up and change greatly.
The bright star-like core of a comet is the nucleus. The nucleus is a glowing halo - the coma. A huge enveloping mass of H gas seen in the UV surrounding the coma is called the
hydrogen cloud.Slide4
Comet StructureSlide5
When a comet get close enough to the Sun it grows a tail.
The tail trails behind the comet in the path it is traveling.
As is gets closer, its orbit curves more, and the tail splits.
One part, the dust tail composed of uncharged particles, still follows the comet. Another tail, the ion tail made of the charged particles emitted from the
comet,
extends away from the Sun.
Comet
TailsSlide6
Some comets (short periods) may circle the Sun and head back toward the
Kuiper
Belt where they may have come from.
The Origin of CometsSlide7
Long period comets with orbital periods of more than 200 years may have originated in the
Oort
cloud
, a vast spherical shell of icy objects about a LY from the Sun.Periodic CometsSlide8
Comet Halley is one of more than 150 named short period comets with orbits less than 200 years.
It was first recorded in 240 B.C.
It returns every 76 years (last seen in 1986).
CometHalleySlide9
Shooting Stars
Shooting Stars are MeteorsSlide10
Meteoroid, Meteor, Meteorite
A
meteoroid
is one of countless bits of rock and dust that populate the inner solar system. A meteor is a streak of light created by a meteoroid as it plunges through our atmosphere. A meteorite is a piece of stone or metal from space that lands on Earth.Slide11
A
meteor shower
is a predictable event every year when you can see meteors pour down from the sky.
During a shower, all the meteors appear to come from one point in the sky, called the radiant. Meteor showers occur when Earth passes through the remains left behind by a comet.
Meteor Showers and DisplaysSlide12
Iron meteorites
, about 8 times the density of water, are composed of mostly iron (90%) and nickel.
Stony meteorites
, about 3 times the density of water, have a high silica content (SiO2). Carbonaceous chondites are stony meteorites with a high carbon content and some water. Meteorites have been found that are believed to have come from impacts on the Moon and Mars.
Makeup of Meteorites