<snip> "Leonid impacts aren't as potent as a nuclear warhead, but they are powerful. They hit the Moon traveling 72 km/s or 160,000 mph -- that's about 100 times faster than a rifle bullet. In fact, the energy per unit mass in a Leonid strike is 10,000 times greater than a blast of TNT."

Here is the NASA site that explains the flashes seen here on Earth.

<snip>
According to Melosh, here's what happens when the Moon and a 10 kg Leonid collide:

Much of the ground within a few meters of the impact point would be vaporized, and a cloud of molten rock would billow out of a growing crater. "At first the cloud would be opaque and very hot, between 50,000 K and 100,000 K," explains Melosh. "But the temperature would drop rapidly. Milliseconds after the initial blast, the cloud would expand to a few meters in diameter and cool to 13,000 K. That's the critical moment," he says, "when the vapor becomes optically thin (transparent); then, all the photons rush out and we can see a flash of light from Earth."
An astronaut watching the event on the Moon, perhaps a hundred meters or so from the impact, would be momentarily blinded by the Sun-bright explosion. There wouldn't be a deafening report, however, and onlookers wouldn't be knocked down. "There's no air on the Moon to carry shock waves," explains Melosh. "Even so, you might have to pry some nasty bits of molten rock out of your space suit."

The site also has video and many good related links at the bottom of the page.

Enjoy
SteveS