March 21, 2022
Somewhere between the Big Bang and this birthday, the universe learned how to make kindness, curiosity, humor, memory, and hope.
The Sky in 2021
Birthday · March 21, 2022
A little universe, just for you
Your date.
Ready to give.
Free PNG · 1080 × 1350 · No account needed
Image rights and credit requirements apply when sharing or reusing imagery.
Date & occasion only
Change the year
APOD published March 21, 2022. Credit: Cees Bassa (Netherlands Institute for Radio Astronomy). A publication-date match, not a photo taken on your date. Independent of NASA.
What if you could see the entire sky -- all at once -- for an entire year? That, very nearly, is what is pictured here. Every 15 minutes during 2021, an all-sky camera took an image of the sky over the Netherlands. Central columns from these images were then aligned and combined to create the featured keogram, with January at the top, December at the bottom, and the middle of the night running vertically just left of center. What do we see? Most obviously, the daytime sky is mostly blue, while the nighttime sky is mostly black. The twelve light bands crossing the night sky are caused by the glow of the Moon. The thinnest part of the black hourglass shape occurs during the summer solstice when days are the longest, while the thickest part occurs at the winter solstice. Yesterday was an equinox -- when night and day were equal -- and the northern-spring equinox from one year ago can actually be located in the keogram -- about three-quarters of the way up. Follow APOD on Instagram in: English, Indonesian, Persian, Portuguese or Taiwanese
Image credit: Cees Bassa (Netherlands Institute for Radio Astronomy)