Tonight, if all goes well, NASA’s Double Asteroid Redirection Test — or DART — mission will slam into a tiny asteroid moon at nearly 24,000 kilometers per hour, blasting out a cloud of debris, creating a flash of light visible across the solar system, and changing the velocity of the asteroid by less than a millimeter per second… which is tiny, but significant.

Impact is planned for 23:14 UTC tonight, which is 7:14 p.m. ET. The flash won’t be visible by eye, but may be observable in small telescopes — see my caveats below. It will be observed by professional astronomers across the planet and by observatories above and beyond it, too.

The point?…