Talk:Meteoroid

How are meteoroids stopped from hitting hard on the earths surface?

How are meteoroids stopped from hitting hard on the earths surface —Preceding unsigned comment added by 59.183.246.63 (talk) 06:45, 17 October 2010 (UTC)

Please reread the introduction to this article. You'll see that Meteoroids that survive the plunge through the Earth's atmosphere and land on the Earth are called meteorites (click on the link to see that article). Best: HarryZilber (talk) 17:15, 17 October 2010 (UTC)

I think the questions was not what but how.

Meteoroids arrive in the upper atmosphere at a given cosmic velocity: typically 25,000-78,000kph(??? approximate from memory needs to be verified???) This cosmic velocity x mass of the meteoroid = momentum/ kinetic energy which is greatly converted to heat and light energy. Much of the mass is carried off as a molten mist further reducing the speed.

The result is both the speed and the mass of the meteoroid is decreasing at an increasing rate. IF the meteoroid is small it will not survive the ablation of entry. Once the speed falls below approximately 4200mph the meteorite stops ablation and incandescence( glowing) . It enters "dark flight" and decelerates to "free fall" velocity. Incandescence cannot continue below approximately 5 miles above sea level. As 95%(???) of the atmosphere lies below 5 miles, the 5 mile mark represents a relatively dense fluid compared to the 120-140 miles of atmosphere the meteoroid has traversed. For most meteoroids under 1 meter at entry, all the cosmic velocity has been depleted at or above by this altitude and the body free falls under normal gravitational acceleration. Depending on initial velocity and mass, can enter dark flight between 100 and 5 miles about sea level. Thus a meteoroid arrives at the ground constrained between 120-400 miles per hour(sorry about the cross use of metric and American measurements) So they do hit the ground hard enough to excavate an "impact pit" which may be none to a few inches to a few feet deep. — Preceding unsigned comment added by Mstreman (talk • contribs) 17:56, 18 September 2011 (UTC)

link rot

This reference can't be called up any more. ^ a b meteorshowersonline.com The Leonids and the Birth of Meteor Astronomy 4.249.63.30 (talk) 17:30, 1 March 2011 (UTC)

People/Objects hit by meteors

I think there is a need for info on people getting hit by it or a link directing to articles that talk about it. Thanks. — Preceding unsigned comment added by 160.109.98.44 (talk) 18:50, 2 August 2011 (UTC)

The direction the Earth travels in its orbit

I am not sure that I improved the article. The explanation that I wrote is true, but the clause preceding the word as in not logically connected to the second clause. Meteors hit the leading hemisphere of the Earth more frequently than they hit the trailing hemisphere, but they hit both hemispheres night and day. Perhaps the reference to the direction the Earth travels in its orbit should just be dropped. Fartherred (talk) 21:08, 12 September 2011 (UTC)

The direction of travel of earth in orbit and the approach azimuth of the meteoroid has implications for meteoroid survival: at 12 noon the speed of the earth along its orbit (15k/sec?) is added to the speed of the meteor-while at 12 midnight the speed is subtracted. Therefore statistically speaking a meteoroid arriving at night undergoes less ablation and is therefore has a better chance of reaching the ground. I am not sure that the argument is true that meteoroids hit the leading edge more often than the trailing edge. Once a meteoroid comes under the gravitational pull of the earth they are drawn in regardless. Some approaching from the rear can be deflected forward and vice versa. Unless we have a specific citation to the contrary I too think this "fact" should be left out.Mstreman (talk) 17:27, 18 September 2011 (UTC)

Colors of meteors

The color section is misleading and the caveat of "possible colors" should be revisited. The current spectra listing is for a chem lab and not for meteoroid composition. Meteor color is derived from both the atmosphere and the makeup of the meteoroid. For example copper is not found in meteorites above the rare microscopic occurrence. Nickel emits a green spectra but the Green color is a combination of magnesium, atmospheric oxygen etc.

For fodder, here is a draft blurb from a paper I am authoring: ... on to specific spectral emissions, the common emissions for metallic atoms in meteors and for atmospheric atoms can be seen at.

<http://leonid.arc.nasa.gov/meteor.html>

Combinations of the two sources of emissions produce the colors one sees in the fireball. “Colors of meteors: The color of many meteors is caused (sic)by light emitted from metal atoms from the meteoroid (blue, green, and yellow) and light emitted by atoms and molecules of the air (red). The metal atoms emit light much like in our sodium discharge lamps: sodium (Na) atoms give an orange-yellow light, iron (Fe) atoms a yellow light, magnesium (Mg) a blue-green light, ionized calcium (Ca+) atoms may add a violet hue, while molecules of atmospheric nitrogen (N2) and oxygen atoms (O) give a red light.( Note: See later discussion of spectral changes in N2 and O2 with decreasing altitude below) The meteor color depends on whether the metal atom emissions or the air plasma emissions dominate“...NASA <http://leonid.arc.nasa.gov/meteor.html>... Mstreman (talk) 18:15, 18 September 2011 (UTC)

Unmerge with meteor

I don't understand why the articles on meteor and meteoroid got merged. These are not the same topic. Meteors can result when large objects pass through the atmosphere, not just small ones. So meteors should not be a subtopic under meteoroids. I suggest unmerging. JeffG (talk) 19:58, 26 December 2011 (UTC)