Astronomy Picture of the Day

   [1]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 September 13
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                  Star Trails over One-Mile Radio Telescope
          Image Credit & [3]Copyright: [4]Joao Yordanov Serralheiro

   Explanation: The steerable 60 foot diameter dish antenna of the
   One-Mile Telescope at [5]Mullard Radio Astronomy Observatory,
   Cambridge, UK, is [6]pointing skyward in this evocative night-skyscape.
   To capture the dramatic scene, consecutive 30 second exposures were
   recorded over a period of 90 minutes. Combined, the exposures reveal a
   background of gracefully arcing star trails that reflect planet Earth's
   daily [7]rotation on its axis. The [8]North Celestial Pole, the
   extension of Earth's axis of rotation into space, points near Polaris,
   the [9]North Star. That's the bright star that creates the short trail
   near the center of the [10]concentric arcs. But the [11]historic
   One-Mile Telescope array also relied on planet Earth's rotation to
   operate. Exploring the universe at [12]radio wavelengths, it was the
   first radio telescope to use Earth-rotation aperture synthesis.
   [13]That technique uses the rotation of the Earth to change the
   relative orientation of the telescope array and celestial radio sources
   to create [14]radio maps of the sky at a resolution better than that of
   the human eye.

                     Tomorrow's picture: tilts and spins
     __________________________________________________________________

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    Authors & editors: [26]Robert Nemiroff ([27]MTU) & [28]Jerry Bonnell
                                 ([29]UMCP)
          NASA Official: Amber Straughn [30]Specific rights apply.
            [31]NASA Web Privacy, [32]Accessibility, [33]Notices;
                A service of: [34]ASD at [35]NASA / [36]GSFC,
                         [37]NASA Science Activation
                           & [38]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2509/StarTrailsOne-MileRadioTelescope2100.jpg
   3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
   4. https://www.joaoysphotography.com/about
   5. https://en.wikipedia.org/wiki/Mullard_Radio_Astronomy_Observatory
   6. https://www.joaoysphotography.com/portfolio?pgid=izo2cln4-f5684d4a-6f79-49cd-a911-84e93c45d8d0
   7. https://apod.nasa.gov/apod/ap090909.html
   8. https://apod.nasa.gov/apod/ap250605.html
   9. https://apod.nasa.gov/apod/ap110514.html
  10. https://apod.nasa.gov/apod/ap100212.html
  11. https://en.wikipedia.org/wiki/One-Mile_Telescope
  12. https://apod.nasa.gov/apod/ap180713.html
  13. https://ui.adsabs.harvard.edu/abs/1973IEEEP..61.1211F/abstract
  14. https://public.nrao.edu/vlass/
  15. https://apod.nasa.gov/apod/ap250912.html
  16. https://apod.nasa.gov/apod/archivepix.html
  17. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  18. https://apod.nasa.gov/apod/lib/aptree.html
  19. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  20. https://apod.nasa.gov/apod/calendar/allyears.html
  21. https://apod.com/feed.rss
  22. https://apod.nasa.gov/apod/lib/edlinks.html
  23. https://apod.nasa.gov/apod/lib/about_apod.html
  24. https://asterisk.apod.com/discuss_apod.php?date=250913
  25. https://apod.nasa.gov/apod/ap250914.html
  26. http://www.phy.mtu.edu/faculty/Nemiroff.html
  27. http://www.phy.mtu.edu/
  28. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  29. http://www.astro.umd.edu/
  30. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  31. https://www.nasa.gov/about/highlights/HP_Privacy.html
  32. https://www.nasa.gov/general/accessibility/
  33. https://www.nasa.gov/privacy/
  34. https://astrophysics.gsfc.nasa.gov/
  35. https://www.nasa.gov/
  36. https://www.nasa.gov/centers/goddard/
  37. https://science.nasa.gov/learners
  38. http://www.mtu.edu/