This was
your sky.
The Comet and the Fireball
This picture was intended to capture Comet Leonard, the brightest comet of 2021. However, a bright meteor, or fireball, streaked through the frame just below the comet. The meteor's flash was even greener than the comet's coma. The meteor's green color likely came from magnesium evaporating from its core, while the comet's green was from diatomic carbon.
We cannot put this date's photograph on paper at poster size. We can print the nearest public archive plate to your date instead.
Prints are coming soon. The card is free to save and share in the meantime.
Released on your day
Space pictures released on your month and day in other years, or a few days either side. Each one is sharp enough to print as a poster.
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Released on 20 December 2023 Dwarf irregular galaxy UGC 8091 (wide-field view) See it as a poster -
Released on 20 December 2018 Galaxy Cluster MACSJ0416 See it as a poster -
Released on 20 December 2018 Intracluster light in Abell S1063 See it as a poster -
Released on 20 December 2021 A Sprinkling of Stars See it as a poster -
Released on 20 December 2024 The city lights of Hong Kong and Shenzhen See it as a poster
In tropical astrology, 20 DEC 2021 falls under Sagittarius (♐). The sign's window runs from 11-22 through 12-21. Sagittarius points straight at the center of the Milky Way, our galaxy's brightest region. The Sun was crossing this region of the sky on 20 DEC 2021.