APOD on Nostr: **Astronomy Picture of the Day** 21 June 2025 **Two Worlds, Two Analemmas** Image ...
**Astronomy Picture of the Day**
21 June 2025
**Two Worlds, Two Analemmas**
Image Credit & Copyright: Tunc Tezel
Sure, that figure-8 shaped curve you get when you mark the position of the Sun in Earth's sky at the same time each day over one year is called an analemma. On the left, Earth's figure-8 analemma was traced by combining wide-angle digital images recorded during the year from December 2011 through December 2012. But the shape of an analemma depends on the eccentricity of a planet's orbit and the tilt of its axis of rotation, so analemma curves can look different for different worlds. Take Mars for example. The Red Planet's axial tilt is similar to Earth's, but its orbit around the same sun is more eccentric (less circular) than Earth's orbit. As seen from the Martian surface, the analemma traced in the right hand panel is shaped more like a tear drop. The Mars rover Opportunity captured the images used over the Martian year corresponding to Earth dates July 2006 to June 2008. Of course, each world's solstice dates still lie at the top and bottom of their different analemma curves. The last Mars northern summer solstice was May 29, 2025. Our fair planet's 2025 northern summer solstice is at June 21, 2:42 UTC.
#APOD #LunarMission #Astrophysics #NASAInspires #GalacticAdventures
https://apod.nasa.gov/apod/ap250621.htmlPublished at
2025-06-21 04:08:22 GMTEvent JSON
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"content": "**Astronomy Picture of the Day**\n\n21 June 2025\n\n**Two Worlds, Two Analemmas**\n\nhttps://apod.nasa.gov/apod/image/2506/AnalemmaEarthMars.jpg\n\nImage Credit \u0026 Copyright: Tunc Tezel\n\nSure, that figure-8 shaped curve you get when you mark the position of the Sun in Earth's sky at the same time each day over one year is called an analemma. On the left, Earth's figure-8 analemma was traced by combining wide-angle digital images recorded during the year from December 2011 through December 2012. But the shape of an analemma depends on the eccentricity of a planet's orbit and the tilt of its axis of rotation, so analemma curves can look different for different worlds. Take Mars for example. The Red Planet's axial tilt is similar to Earth's, but its orbit around the same sun is more eccentric (less circular) than Earth's orbit. As seen from the Martian surface, the analemma traced in the right hand panel is shaped more like a tear drop. The Mars rover Opportunity captured the images used over the Martian year corresponding to Earth dates July 2006 to June 2008. Of course, each world's solstice dates still lie at the top and bottom of their different analemma curves. The last Mars northern summer solstice was May 29, 2025. Our fair planet's 2025 northern summer solstice is at June 21, 2:42 UTC.\n\n#APOD #LunarMission #Astrophysics #NASAInspires #GalacticAdventures\n\nhttps://apod.nasa.gov/apod/ap250621.html\n",
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