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  2. Sidereal time - Wikipedia

    en.wikipedia.org/wiki/Sidereal_time

    An increase of 360° in the ERA is a full rotation of the Earth. A sidereal day on Earth is approximately 86164.0905 seconds (23 h 56 min 4.0905 s or 23.9344696 h). (Seconds are defined as per International System of Units and are not to be confused with ephemeris seconds.)

  3. Earth Day - Wikipedia

    en.wikipedia.org/wiki/Earth_Day

    The goal of Earth Day 2014 was to dramatically personalize the massive challenges surrounding global climate change and weave that into both Earth Day 2014 and the five-year countdown to Earth Day 2020, the 50th anniversary. It was an opportunity to unite people worldwide into a common cause and call for action. [110]

  4. Unit of time - Wikipedia

    en.wikipedia.org/wiki/Unit_of_time

    Subdivisions of the day include the hour (1/24 of a day), which is further subdivided into minutes and seconds. The second is the international standard unit (SI unit) for science. Celestial sphere-based: as in sidereal time, where the apparent movement of the stars and constellations across the sky is used to calculate the length of a year.

  5. When is Earth Day? Knock your stalks off by celebrating ... - AOL

    www.aol.com/earth-day-knock-stalks-off-082217813...

    The first official Earth Day happened a year after his initial idea for a national teach-in, on April 22, 1970. The beauty of recycling: Practice your 'R's' for Earth Day.

  6. 10 Surprising Facts About Earth Day - AOL

    www.aol.com/10-surprising-facts-earth-day...

    A college student in a gas mask "smells" a magnolia blossom during the first Earth Day on April 22, 1970 in New York City. Credit - AP. M ore than 8 billion people inhabit Earth, and soon a ...

  7. Equation of time - Wikipedia

    en.wikipedia.org/wiki/Equation_of_time

    The equation of time is the east or west component of the analemma, a curve representing the angular offset of the Sun from its mean position on the celestial sphere as viewed from Earth. The equation of time values for each day of the year, compiled by astronomical observatories, were widely listed in almanacs and ephemerides. [2] [3]: 14

  8. ΔT (timekeeping) - Wikipedia

    en.wikipedia.org/wiki/ΔT_(timekeeping)

    Analysis of layering in fossil mollusc shells from 70 million years ago, in the Late Cretaceous period, shows that there were 372 days a year, and thus that the day was about 23.5 hours long then. [ 20 ] [ 21 ] Based on geological studies of tidal rhythmites , the day was 21.9±0.4 hours long 620 million years ago and there were 13.1±0.1 ...

  9. 20 Earth Day facts that aren't common knowledge - AOL

    www.aol.com/news/10-earth-day-facts-might...

    Earth day went global in 1990. About 20 years after the concept of Earth Day was created in the 1970s, the campaign began to spread internationally. The 1990 Earth Day demonstration included ...