On Friday, an asteroid traveling 23,000 mph will pass by Earth at a distance of 0.03 astronomical units (AU).
If that sounds ominously close, it's not really. Despite the breathless hyperbole from some about the asteroid "skimming past" Earth on a "near-collision course," 0.03 AU is the equivalent of 2,788,674 miles. That's 11.7 times greater than the distance from the Earth to the moon.
The space rock, known formally as 2014-YB35, will be close enough for astronomers to get a good look but basically invisible to everyone else.
According to NASA's Goldstone Asteroid Schedule, YB35 is about 500 meters (1,640 feet) in diameter. Beyond that, not much is known about the asteroid.
There have been much closer calls in the past. In January, asteroid 2004 BL86 cruised past Earth at a distance of about 745,000 miles, close enough for scientists at NASA's Deep Space Network antenna to capture images of the rock, which they discovered is orbited by its own small moon: