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  2. Epoch (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Epoch_(astronomy)

    In astronomy, an epoch or reference epoch is a moment in time used as a reference point for some time-varying astronomical quantity. It is useful for the celestial coordinates or orbital elements of a celestial body , as they are subject to perturbations and vary with time. [ 1 ]

  3. Epoch - Wikipedia

    en.wikipedia.org/wiki/Epoch

    An epoch in astronomy is a reference time used for consistency in calculation of positions and orbits. A common astronomical epoch is J2000, which is noon on January 1, 2000, Terrestrial Time. An epoch in Geochronology is a time period, typically in the order of tens of millions of years. The current epoch is the Holocene.

  4. Equinox (celestial coordinates) - Wikipedia

    en.wikipedia.org/wiki/Equinox_(celestial...

    The earlier epoch that was in standard use was the B1950.0 epoch. When the mean equator and equinox of J2000 are used to define a celestial reference frame, that frame may also be denoted J2000 coordinates or simply J2000.

  5. Recombination (cosmology) - Wikipedia

    en.wikipedia.org/wiki/Recombination_(cosmology)

    In cosmology, recombination refers to the epoch during which charged electrons and protons first became bound to form electrically neutral hydrogen atoms.Recombination occurred about 378 000 years [1] after the Big Bang (at a redshift of z = 1100). [2]

  6. Julian year (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Julian_year_(astronomy)

    In astronomy, an epoch specifies a precise moment in time. The positions of celestial objects and events, as measured from Earth, change over time, so when measuring or predicting celestial positions, the epoch to which they pertain must be specified. A new standard epoch is chosen about every 50 years.

  7. NASA's SPHEREx space telescope to explore what happened right ...

    www.aol.com/news/nasas-spherex-space-telescope...

    SPHEREx - short for Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer - is looking to answer questions about the origin of the universe while mapping the ...

  8. Astronomical coordinate systems - Wikipedia

    en.wikipedia.org/wiki/Astronomical_coordinate...

    Coordinate systems in astronomy can specify an object's relative position in three-dimensional space or plot merely by its direction on a celestial sphere, if the object's distance is unknown or trivial. Spherical coordinates, projected on the celestial sphere, are analogous to the geographic coordinate system used on the surface of Earth.

  9. 11 must-see astronomy events in 2025 - AOL

    www.aol.com/weather/11-must-see-astronomy-events...

    From planetary meet-ups to the first total lunar eclipse in three years, here are the top astronomy events to look for throughout 2025: Stellar views of Mars will greet stargazers in January as ...