by neufer » Sun Oct 02, 2011 3:03 pm
Chris Peterson wrote:orin stepanek wrote:
I always thought that a meteor was when it was burning in the atmosphere and a meteoroid was the pieces that made it to the ground.
A meteoroid is the parent body (which could be of cometary material), either in space or in the atmosphere. The atmospheric phenomenon is a meteor. If a piece makes it to the ground, it is called a meteorite (although meteorwrongs are much more common <g>).
http://en.wikipedia.org/wiki/Asteroid#Terminology wrote:
<<Traditionally, small bodies orbiting the Sun were classified as asteroids, comets
or meteoroids,
with anything smaller than ten metres across being called a meteoroid. The term "asteroid" is ill-defined. It never had a formal definition, with the broader term minor planet being preferred by the International Astronomical Union from 1853 on. In 2006, the term "Small Solar System Body" was introduced to cover both most minor planets and comets. Other languages prefer "planetoid" (Greek for "planet-like"), and this term is occasionally used in English for the larger asteroids. The word "planetesimal" has a similar meaning, but refers specifically to the small building blocks of the planets that existed when the Solar System was forming. The term "planetule" was coined by the geologist William Daniel Conybeare to describe minor planets, but is not in common use. The three largest objects in the asteroid belt, Ceres, 2 Pallas, and 4 Vesta, grew to the stage of protoplanets. Ceres has been designated as a dwarf planet, the only one in the inner Solar System.
When found, asteroids were seen as a class of objects distinct from comets, and there was no unified term for the two until "Small Solar System Body" was coined in 2006. The main difference between an asteroid and a comet is that a comet shows a coma due to sublimation of near surface ices by solar radiation. A few objects have ended up being dual-listed because they were first classified as minor planets but later showed evidence of cometary activity. Conversely, some (perhaps all) comets are eventually depleted of their surface volatile ices and become asteroids. A further distinction is that comets typically have more eccentric orbits than most asteroids; most "asteroids" with notably eccentric orbits are probably dormant or extinct comets.>>
http://en.wikipedia.org/wiki/Meteor#Meteor wrote:
<<
A meteor is the visible path of a meteoroid that has entered the Earth's atmosphere. Meteors typically occur in the mesosphere, and most range in altitude from 75 km to 100 km. Millions of meteors occur in the Earth's atmosphere every day. Most meteoroids that cause meteors are about the size of a pebble. They become visible between about 65 and 120 kilometers above the Earth. They disintegrate at altitudes of 50 to 95 kilometers. Meteors have roughly a fifty percent chance of a daylight (or near daylight) collision with the Earth. Most meteors are, however, observed at night as low light conditions allow fainter meteors to be observed.
For bodies with a size scale larger than the atmospheric mean free path (10 cm to several metres) the visibility is due to the atmospheric ram pressure (not friction) that heats the meteoroid so that it glows and creates a shining trail of gases and melted meteoroid particles. The gases include vaporized meteoroid material and atmospheric gases that heat up when the meteoroid passes through the atmosphere. Most meteors glow for about a second. A relatively small percentage of meteoroids hit the Earth's atmosphere and then pass out again: these are termed Earth-grazing fireballs (for example The Great Daylight 1972 Fireball).
Meteors may occur in showers, which arise when the Earth passes through a trail of debris left by a comet, or as "random" or "sporadic" meteors, not associated with a specific single cause. A number of specific meteors have been observed, largely by members of the public and largely by accident, but with enough detail that orbits of the meteoroids producing the meteors have been calculated. All of the orbits passed through the asteroid belt.>>
[quote="Chris Peterson"][quote="orin stepanek"]
I always thought that a meteor was when it was burning in the atmosphere and a meteoroid was the pieces that made it to the ground. :?[/quote]
A meteoroid is the parent body (which could be of cometary material), either in space or in the atmosphere. The atmospheric phenomenon is a meteor. If a piece makes it to the ground, it is called a meteorite (although meteorwrongs are much more common <g>).[/quote]
[quote=" http://en.wikipedia.org/wiki/Asteroid#Terminology"]
<<Traditionally, small bodies orbiting the Sun were classified as asteroids, comets [size=200][u]or[/u][/size] meteoroids, [b][color=#0000FF][u]with anything smaller than ten metres across being called a meteoroid[/u][/color][/b]. The term "asteroid" is ill-defined. It never had a formal definition, with the broader term minor planet being preferred by the International Astronomical Union from 1853 on. In 2006, the term "Small Solar System Body" was introduced to cover both most minor planets and comets. Other languages prefer "planetoid" (Greek for "planet-like"), and this term is occasionally used in English for the larger asteroids. The word "planetesimal" has a similar meaning, but refers specifically to the small building blocks of the planets that existed when the Solar System was forming. The term "planetule" was coined by the geologist William Daniel Conybeare to describe minor planets, but is not in common use. The three largest objects in the asteroid belt, Ceres, 2 Pallas, and 4 Vesta, grew to the stage of protoplanets. Ceres has been designated as a dwarf planet, the only one in the inner Solar System.
When found, asteroids were seen as a class of objects distinct from comets, and there was no unified term for the two until "Small Solar System Body" was coined in 2006. The main difference between an asteroid and a comet is that a comet shows a coma due to sublimation of near surface ices by solar radiation. A few objects have ended up being dual-listed because they were first classified as minor planets but later showed evidence of cometary activity. Conversely, some (perhaps all) comets are eventually depleted of their surface volatile ices and become asteroids. A further distinction is that comets typically have more eccentric orbits than most asteroids; most "asteroids" with notably eccentric orbits are probably dormant or extinct comets.>>[/quote]
[quote=" http://en.wikipedia.org/wiki/Meteor#Meteor"]
<<[b][color=#0000FF]A meteor is [u]the visible path of a meteoroid[/u] that has entered the Earth's atmosphere.[/color][/b] Meteors typically occur in the mesosphere, and most range in altitude from 75 km to 100 km. Millions of meteors occur in the Earth's atmosphere every day. Most meteoroids that cause meteors are about the size of a pebble. They become visible between about 65 and 120 kilometers above the Earth. They disintegrate at altitudes of 50 to 95 kilometers. Meteors have roughly a fifty percent chance of a daylight (or near daylight) collision with the Earth. Most meteors are, however, observed at night as low light conditions allow fainter meteors to be observed.
For bodies with a size scale larger than the atmospheric mean free path (10 cm to several metres) the visibility is due to the atmospheric ram pressure (not friction) that heats the meteoroid so that it glows and creates a shining trail of gases and melted meteoroid particles. The gases include vaporized meteoroid material and atmospheric gases that heat up when the meteoroid passes through the atmosphere. Most meteors glow for about a second. A relatively small percentage of meteoroids hit the Earth's atmosphere and then pass out again: these are termed Earth-grazing fireballs (for example The Great Daylight 1972 Fireball).
Meteors may occur in showers, which arise when the Earth passes through a trail of debris left by a comet, or as "random" or "sporadic" meteors, not associated with a specific single cause. A number of specific meteors have been observed, largely by members of the public and largely by accident, but with enough detail that orbits of the meteoroids producing the meteors have been calculated. All of the orbits passed through the asteroid belt.>>[/quote]