When they look at sky brightness—what they call the sky background—they use a unit of brightness per area of the sky: how much light is spread out over a given parcel of celestial real estate.

The green-hued fireball was seen over North America at 2:29 EDT (0629 GMT) on June 25, blazing a northerly path through the ...

ALEXANDRIA, La. (KALB) - On Saturday night, just after 10 p.m., many people as far north as Tennessee saw what appeared to be a fireball moving slowly across the night sky. The Ursid meteor shower ...

Nature - Height of the Atmosphere Determined from the Time of Disappearance of Blue Colour of the Sky after Sunset Skip to main content Thank you for visiting nature.com.

By Monica Garrett and Steve Tuemmler, CNN (CNN) — A roughly 1-meter (3-foot) asteroid burned up in Earth’s atmosphere over the Philippines near Luzon Island early Wednesday afternoon ...