Editing Micrometeoroid (section)

== Origins and orbits ==
{{see also|Cosmic dust}}

Micrometeoroids are very small pieces of rock or metal broken off from larger chunks of rock and debris often dating back to the birth of the [[Solar System]]. Micrometeoroids are extremely common in space. Tiny particles are a major contributor to [[space weathering]] processes. When they hit the surface of the [[Moon]], or any airless body ([[Mercury (planet)|Mercury]], the [[asteroid]]s, etc.), the resulting melting and vaporization causes darkening and other optical changes in the [[regolith]]. 

Micrometeoroids have less stable [[orbit]]s than meteoroids, due to their greater [[surface area]] to [[mass]] ratio. Micrometeoroids that fall to Earth can provide information on millimeter scale heating events in the [[solar nebula]]. [[Meteorites]] and [[micrometeorites]] (as they are known upon arrival at the Earth's surface) can only be collected in areas where there is no terrestrial [[sedimentation]], typically polar regions. Ice is collected and then melted and filtered so the micrometeorites can be extracted under a microscope. 

Sufficiently small micrometeoroids avoid significant heating on entry into [[Earth]]'s atmosphere.<ref>P. Fraundorf (1980) The distribution of temperature maxima for micrometeorites decelerated in the Earth's atmosphere without melting ''Geophys. Res. Lett.'' '''10''':765-768.</ref> Collection of such particles by high-flying aircraft began in the 1970s,<ref>D. E. Brownlee, D. A. Tomandl and E. Olszewski (1977) Interplanetary dust: A new source of extraterrestrial material for laboratory studies, ''Proc. Lunar Sci. Conf. '''8th''':149-160.''</ref> since which time these samples of stratosphere-collected [[Interplanetary dust cloud#Collecting interplanetary dust on earth|interplanetary dust]] (called ''Brownlee particles'' before their extraterrestrial origin was confirmed) have become an important component of the [[extraterrestrial materials]] available for study in laboratories on Earth.