US Naval Oceanography Portal

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About the US Naval Oceanography Portal

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The Astronomical Applications Department of the U.S. Naval Observatory computes, from fundamental astronomical reference data, the position, brightness, and other observable characteristics of celestial bodies, as well as the circumstances of astronomical phenomena.

This information is of critical importance to navigation, military operations planning, scientific research, surveying, accident reconstruction, architecture, and everyday activities.

Access the Data

Contents of the Data

Rise/Set/Transit/Twilight Data

  • Complete Sun and Moon Data for One Day
  • Table of Sunrise/Sunset, Moonrise/Moonset, or Twilight Times for an Entire Year
  • Rise/Set/Transit Times for Major Solar System Objects and Bright Stars
  • Duration of Daylight/Darkness Table for One Year

Phases of the Moon

  • Dates of Primary Phases of the Moon
  • Fraction of the Moon Illuminated - What the Moon Looks Like Today

Eclipses and Transits

  • Eclipses of the Sun and Moon
  • Solar Eclipse Computer - Computes circumstances for selected solar eclipses at any given location.
  • Lunar Eclipse Computer - Computes circumstances for selected lunar eclipses at any given location.
  • Recent and Upcoming Transits of Mercury and Venus
  • Transit Computer - Computes circumstances for selected transits of Mercury and Venus at any given location.

Positions of Selected Celestial Objects

  • Altitude and Azimuth of the Sun or Moon During One Day
  • Topocentric Configuration of Major Solar System Bodies
  • Geocentric Positions of Major Solar System Objects and Bright Stars
  • Topocentric Positions of Major Solar System Objects and Bright Stars

Synthetic Views of the Earth and Solar System Bodies

  • Day and Night Across the Earth - creates synthetic views of the Earth's surface (in grayscale or color) for any date and time.
  • Apparent Disk of Solar System Object - creates a synthetic image of the telescopic appearance of the Moon or other solar system object for specified date and time.


  • Earth's Seasons - Equinoxes, Solstices, Perihelion,and Aphelion 2000-2020
  • Spring Phenomena, 25 BCE to 38 CE
  • Julian Date Conversion

Celestial Navigation

  • Celestial Navigation Data provides computed altitudes and azimuths and other data for an assumed position and time.
  • Navigational Star Chart


  • Astronomical Almanac Online provides complementary data to the printed Astronomical Almanac.
  • International Celestial Reference System (ICRS) - Important Links
  • Occultations of Stars by Asteroids (International Occultation Timing Association)