The sky is an unobstructed view upward from the surface of the Earth. It includes the atmosphere and outer space. It may also be considered a place between the ground and outer space, thus distinct from outer space. In the field of astronomy, the sky is also called the celestial sphere. This is an abstract sphere, concentric to the Earth, on which the Sun, Moon, planets, and stars appear to be drifting. The celestial sphere is conventionally divided into designated areas called constellations. Usually, the term sky informally refers to a perspective from the Earth's surface; however, the meaning and usage can vary. An observer on the surface of the Earth can see a small part of the sky, which resembles a dome appearing flatter during the day than at night. In some cases, such as in discussing the weather, the sky refers to only the lower, denser layers of the atmosphere. The daytime sky appears blue because air molecules scatter shorter wavelengths of sunlight more than longer ones.

Read more in the app

Green comet will appear in the night sky for the first time since the Stone Age

‘Green Comet’ Begins Closest Approach To Earth As A ‘Snow Moon’ Shines Near Mars: The Night Sky This Week

Light Pollution Is Dimming Our View of the Sky, and It's Getting Worse

Bizarre Bright Spiral In The Sky Spotted By Astronomers Identified

SpaceX Starlink launch spawns gorgeous dawn clouds in Florida sky

See Mercury at its highest point in the sky Tuesday morning (Jan. 24)

See A Crescent Moon Tangle With Saturn And Venus: The Night Sky This Week

A Rare Green Comet Can Be Seen in The Sky, And It May Be Our Last Chance

Don't miss Saturn and Venus together in the night sky tonight

Venus will steal the show in the night sky throughout 2023

Light Pollution is Obscuring the Night Sky. RIP Stargazing

SpaceX rocket creates eerie blue spiral in night sky over Hawaii: reports

Stars? What stars? We've nearly succeeded in extinguishing the night sky

Light pollution is erasing stars from the night sky at breakneck pace. It's only going to get worse.

The Night Sky Is Twice as Bright as It Was Only 8 Years Ago

Vanishing Stars: The Alarming Global Trend of Losing Sight of the Night Sky

New data show how quickly light pollution is obscuring the night sky

Light pollution is drowning the starry night sky faster than thought

'Absolutely bonkers' aurora lights up the sky above Iceland (video)

Watch Venus and Saturn begin joining up in the night sky this week