                        Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our
      fascinating universe is featured, along with a brief explanation
                    written by a professional astronomer.

                               2025 January 4

                            Welcome to Perihelion
       Image Credit & Copyright: Peter Ward (Barden Ridge Observatory)

   Explanation: Earth's orbit around the Sun is not a circle, it's an
   ellipse. The point along its elliptical orbit where our fair planet is
   closest to the Sun is called perihelion. This year perihelion is today,
   January 4, at 13:28 UTC, with the Earth about 147 million kilometers
   from the Sun. For comparison, at aphelion on last July 3 Earth was at
   its farthest distance from the Sun, some 152 million kilometers away.
   But distance from the Sun doesn't determine Earth's seasons. It's only
   by coincidence that the beginning of southern summer (northern winter)
   on the December solstice - when this H-alpha picture of the active Sun
   was taken - is within 14 days of Earth's perihelion date. And it's only
   by coincidence that Earth's perihelion date is within 11 days of the
   historic perihelion of NASA's Parker Solar Probe. Launched in 2018, the
   Parker Solar Probe flew within 6.2 million kilometers of the Sun's
   surface on 2024 December 24, breaking its own record for closest
   perihelion for a spacecraft from planet Earth.

                      Tomorrow's picture: rocket launch
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
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                      A service of: ASD at NASA / GSFC,
                           NASA Science Activation
                             & Michigan Tech. U.

