Chondrules - An origin by impacts between dust grains

Modern theories regarding the origin of chondrules may be divided into two broad categories. According to primary theories, chondrules are thought to condense directly from the cooling nebular gas as stable or metastable liquid droplets. According to secondary theories, chondrules are thought to be produced by the flash heating and remelting of the original dust-like condensate. A collisional mechanism of chondrule formation is discussed.