Sky surveys typically catch one or twoeach week, on average. But it's more rare to spot one early enough to be able to get the word out in time that the public would have any chance of seeing it as it makes its close pass above us.
In recent years, a new near-Earth asteroid passing closer than the orbit of the moon (also known as one lunar distance or about 239,000 miles/385,000 kilometers) will typically be identified, confirmed and cataloged just before or after it has already zipped by us and back out to space. But this month a significant cluster of asteroids have been discovered that will pass by at less than one lunar distance, according to NASA's catalog of near-Earth objects.
The closest of these will be asteroid 2020 UA, which will come within 29,000 miles (46,000 kilometers) of Earth on Tuesday evening (Wednesday in Europe, Africa, Australia and Asia). That's within a few thousand miles of where many of our large communications satellites are parked in what's called geosynchronous orbit.
There's no actual risk of this space rock colliding with our planet or any satellites that we know of, but it is what astronomer Gianluca Masi of the Virtual Telescope Project in Rome calls an "extremely close encounter."
Fortunately, it was discovered with enough lead time that the Virtual Telescope Project will be streaming an online observing session as 2020 UA makes its close pass.
The show is set to begin at 3 p.m. PT on Tuesday and you can watch it right here in the feed below: