John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
It's the first time in known history that something like this could be viewed by so many people.
If there's one thing you can count on in life, it's that the stars are generally going to keep shining and not pull any shenanigans.
But tonight the celestial map is due for a shake-up, with one star over New York City (and beyond) winking out of sight for as long as 14 seconds.
What's happening is that an asteroid about 110 million miles from Earth is about to pass in front of Regulus, an extremely bright, egg-shaped star in the constellation of Leo. The occultation will create a thin but long band of shadow over the Northeast and into Ontario, with people in New York getting the chance to see the star disappear at roughly 2:06 a.m. (Those northward will have to wait and extra minute or two.)
Stars are sometimes blotted out by planets and the moon. But this far-away photo-bombing by an asteroid will make it seem like Regulus has not been replaced by another physical body, but dropped out of existence entirely. The millions of people who might witness the phenomenon marks it as an extremely rare event. According to Tony Phillips at Spaceweather: "This is the first time in recorded history that an asteroid blacks out a naked-eye star in view of such a heavily populated area."
Here's the expected swoop of the asteroid's shadow, courtesy of the International Occultation Timing Association:
So where do you find Regulus? In a fine write-up of tonight's event, Sky & Telescope advises:
If the sky is clear, Regulus will be a cinch for anyone to spot – no astronomy experience required! Around 2 a.m. (or a bit before), go out and face the Moon. Extend your arms straight out to your sides. Regulus will be straight above your right hand, roughly as high as the Moon is. It's the brightest star in that area.
"Regulus shines right through moonlight and light pollution that's in the sky – even the light pollution over a city like New York," says Alan MacRobert, a senior editor at Sky & Telescope magazine. "Just be sure to shield your eyes against any glary lights, and Regulus should be easy to find."
About that if "the sky is clear" clause: There's an increasing chance that a rain-and-sleet-flinging system moving over the Northeast could muck up the star-viewing situation. To find the latest on visibility conditions, check out the ongoing discussion at New York's National Weather Service.
Top photo of a star-making galaxy courtesy of NASA