micrometeoroid

mi cro me te or oid |ˌmīkrōˈmēteəˌroid ˈmaɪkroʊˌˈmitɛərɔɪd | ▶noun a microscopic particle in space or of extraterrestrial origin that is small enough so that if it enters the earth's atmosphere, it will not burn up but drift to the earth's surface instead.

micrometeoroid

micro |meteor |oid |mʌɪkrəʊˈmiːtɪərɔɪd | ▶noun a microscopic particle in space or of extraterrestrial origin which is small enough not to burn up in the earth's atmosphere but to drift to the surface instead.