What Happens When a Comet Hits the Moon?

Full transcript

A comet hurtling through space can travel tens of kilometers per second, and because the Moon has almost no atmosphere, absolutely nothing slows it down on approach. At the instant of impact, the comet and a chunk of the lunar surface are instantly vaporized, producing a brilliant flash of light that would be clearly visible from Earth. The collision excavates a massive crater, hurling enormous quantities of pulverized and molten rock outward in every direction across the lunar surface. Rock fragments called ejecta can be thrown hundreds or even thousands of kilometers away, and some pieces move fast enough to escape the Moon's gravity and drift into open space. The enormous energy of the impact also sends powerful seismic shock waves rippling through the Moon's interior, potentially triggering moonquakes detectable all across the globe. Despite all this destruction, even a very large comet would not shatter the Moon, because with a mass of about 7.35 times ten to the twenty-two kilograms, the Moon is simply too massive to be blown apart.