December Gallery

Us-Nasa-Earth-Longest Zday

This 1972 NASA photo shows a view of the Earth as seen by the Apollo 17 astronauts. NASA announced 22 January, 2002 that all days are not created equal. The summer solstice, 21 June, when the period between sunrise and sunset is the longest in the northern hemisphere, is actually not the longest day ever recorded. The longest day in the past century occurred sometime during 1912, according to JPL geophysicist Dr. Richard Gross. The shortest day in the past 100 years was 02 August, 2001, when the length of time that it took Earth to make one complete turn on its axis actually dipped below 24 hours by about one-thousandth of a second. According to Gross, the length of the day changes about a millisecond over the course of a year. It gradually increases in the winter, when Earth rotates more slowly, and decreases in the summer. There are also longer patterns of changes in the length of day that last decades, even centuries. AFP PHOTO/ NASA / AFP PHOTO / NASA / NASA FILES

© Agence France-Presse (AFP) - All Rights Reserved