NASA will roll its Artemis 2 moon rocket out to the launch pad on Saturday (Jan. 17), and you can watch the slow-moving action live.
Around the sun, there are countless small bodies whose orbits occasionally bring them in close proximity to Earth, known as Near-Earth Objects (NEOs). There are currently 37,000 known Near-Earth Asteroids (NEAs) and 120 known short-period near-Earth comets (NECs), though astronomers estimate that these objects number in the millions. Of particular concern are asteroids and comets that pose a potential impact risk to Earth, known as Potentially Hazardous Objects (PHOs). While scientists are confident that none of the known PHOs will pose a risk to Earth within the next century, planetary defense measures will be needed sooner or later.

