Hour
Videos
An hour is a unit of time historically reckoned as 1⁄24 of a day and defined contemporarily as exactly 3,600 seconds. There are 60 minutes in an hour, and 24 hours in a day. As defined by a second, an
A 7th-century Saxon tide dial on the porch at Bishopstone in Sussex, with larger crosses marking the canonical hours.
Sundial with Italian hours in Asti
A Chinese diagram from Su Song's AD 1092 Xinyi Xiangfa Yao illustrating his clocktower at Kaifeng.
A reconstruction of another kind of Chinese clepsydra in Beijing's Drum Tower
Day
Videos
A day is the time period of a full rotation of the Earth with respect to the Sun. On average, this is 24 hours. As a day passes at a given location it experiences morning, afternoon, evening, and nigh
Hour
…An hour (symbol: h; also abbreviated hr) is a unit of time historically reckoned as 1⁄24 of a day and defined contemporarily as exactly 3,600 seconds. There are 60 minutes in an hour, and 24 hours in a day. As defined by a second, an hour is equal…
Decimal clock face, made in around the start of the 19th century
Night in art
Midtown Manhattan from Weehawken September 2021 panorama 1
Midtown Manhattan from Weehawken September 2021 panorama 2