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.

                                 2024 July 1
     [2]An illustrated spiral is shown depicting many significant events
    that have occurred since the big bang. The big bang is at the center,
      and a city built by humans is at the spiral's end. Please see the
                 explanation for more detailed information.

                                 Time Spiral
        Illustration Credit: [3]Pablo Carlos Budassi via [4]Wikipedia

   Explanation: What's happened since the universe started? The time
   spiral [5]shown here features a few [6]notable highlights. At the
   spiral's center is the [7]Big Bang, the place where [8]time, as we know
   it, began about 13.8 billion years ago. Within a few billion years
   [9]atoms formed, then [10]stars formed from atoms, [11]galaxies formed
   from stars and gas, [12]our Sun formed, soon followed by [13]our Earth,
   about 4.6 billion years ago. [14]Life on Earth begins about 3.8 billion
   years ago, followed by [15]cells, then [16]photosynthesis within a
   billion years. About 1.7 billion years ago, [17]multicellular life on
   Earth began to flourish. [18]Fish began to swim about 500 million years
   ago, and [19]mammals because walking on land about 200 million years
   ago. [20]Humans first appeared only about 6 million years ago, and made
   the [21]first cities only about 10,000 years ago. The time spiral
   illustrated stops there, but human [22]spaceflight might be added,
   which started only 75 years ago, and useful [23]artificial intelligence
   began to take hold within only the past few years.

              Explore Your Universe: [24]Random APOD Generator
                      Tomorrow's picture: oyster stars
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   [30]Calendar | [31]RSS | [32]Education | [33]About APOD | [34]Discuss |
                                    [35]>
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    Authors & editors: [36]Robert Nemiroff ([37]MTU) & [38]Jerry Bonnell
                                 ([39]UMCP)
          NASA Official: Amber Straughn [40]Specific rights apply.
            [41]NASA Web Privacy, [42]Accessibility, [43]Notices;
                A service of: [44]ASD at [45]NASA / [46]GSFC,
                         [47]NASA Science Activation
                           & [48]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2407/TimeSpiral_Budassi_2500.jpg
   3. https://commons.wikimedia.org/wiki/User:Unmismoobjetivo
   4. https://en.wikipedia.org/wiki/Wikipedia
   5. https://commons.wikimedia.org/wiki/File:Nature_timespiral_vertical_layout.png
   6. https://apod.nasa.gov/apod/ap171126.html
   7. https://webb.nasa.gov/content/features/bigBangQandA.html
   8. https://en.wikipedia.org/wiki/Time
   9. https://youtu.be/cx1z0jwzWjI
  10. https://science.nasa.gov/universe/stars/
  11. https://apod.nasa.gov/apod/ap230531.html
  12. https://science.nasa.gov/sun/
  13. https://science.nasa.gov/earth/facts/
  14. https://cneos.jpl.nasa.gov/about/life_on_earth.html
  15. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7087693/
  16. https://en.wikipedia.org/wiki/Photosynthesis
  17. https://astrobiology.nasa.gov/news/how-did-multicellular-life-evolve/
  18. https://youtu.be/t6ORDd4ZpXg
  19. https://en.wikipedia.org/wiki/Mammal
  20. https://apod.nasa.gov/apod/ap190818.html
  21. https://youtu.be/H1jHdnZ2U3o
  22. https://apod.nasa.gov/apod/ap181001.html
  23. https://media.snopes.com/2009/01/rand.jpg
  24. https://apod.nasa.gov/apod/random_apod.html
  25. https://apod.nasa.gov/apod/ap240630.html
  26. https://apod.nasa.gov/apod/archivepix.html
  27. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  28. https://apod.nasa.gov/apod/lib/aptree.html
  29. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  30. https://apod.nasa.gov/apod/calendar/allyears.html
  31. https://apod.com/feed.rss
  32. https://apod.nasa.gov/apod/lib/edlinks.html
  33. https://apod.nasa.gov/apod/lib/about_apod.html
  34. https://asterisk.apod.com/discuss_apod.php?date=240701
  35. https://apod.nasa.gov/apod/ap240702.html
  36. http://www.phy.mtu.edu/faculty/Nemiroff.html
  37. http://www.phy.mtu.edu/
  38. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  39. http://www.astro.umd.edu/
  40. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  41. https://www.nasa.gov/about/highlights/HP_Privacy.html
  42. https://www.nasa.gov/general/accessibility/
  43. https://www.nasa.gov/privacy/
  44. https://astrophysics.gsfc.nasa.gov/
  45. https://www.nasa.gov/
  46. https://www.nasa.gov/centers/goddard/
  47. https://science.nasa.gov/learners
  48. http://www.mtu.edu/