A meteoroid is a relatively small (sand- to boulder-sized) fragment of
debris in the
Solar
System. When entering a
planet's
atmosphere, the meteoroid is heated up by ram pressure and partially or
completely vaporizes. The gas along the path of the meteoroid becomes
ionized and
glows. The trail of glowing vapor is called a
meteor,
or a shooting star. If any portion of the meteoroid survives to reach the
ground, it is then referred to as a
meteorite.
The current
International Astronomical Union (IAU) definition dates back to the XIth
General Assembly, held in
1961:
- "A solid object moving in interplanetary space, of a size considerably
smaller than an asteroid and considerably larger than an atom or molecule."
As a result of the inexorable progress of instrumentation, this definition is
now deemed by many as unacceptably vague. The most common definition was
proposed in 1995
[1]
and sets the size limits of meteoroids to between 100 µm and 10 m across. Larger
than that, the object is an
asteroid;
smaller than that, it is
interplanetary dust.
References
-
^
Beech, M.;
Steel, D. I. (September 1995). "On
the Definition of the Term Meteoroid". Quarterly Journal of the Royal
Astronomical Society 36 (3): 281–284. Retrieved on
2006-08-31.)
