Bright Lunar Impacts and Sporadic Meteors

The main meteor streams and the sporadic population of meteoroids are responsible for the actual modifications of the lunar surface. Since 1999 Leonids, several impacts have been unambiguously recorded [1-3]. Dealing with flashes of m_v ~ 3÷7 magnitude, we studied their masses M and their luminous efficiency η at different impacting velocities V. Let η be the ratio between the luminous energy released during the impact and the incoming kinetic energy: for η γ [2 ÷ 40]% we obtained mass' impactor values ranging from M_str ~ 2/η and M_sp ~ 20/η (M in Kg), the difference arising from impacts' velocities. Such values are well beyond (~ 100 times larger) the previous estimates [4], compared with our predictions in the table.