The Earth's obliquity (i.e., its axial tilt with respect to the orbital plane) is the real critical factor here. The Earth's obliquity was about 0.7° greater (24.14° vs. 23.44°) when Stonehenge was first built circa 3000 BCE. This would be, more or less, equivalent to Stonehenge effectively being about 0.7° further north (51.88°N vs. 51.18°N) in a sunrise/sunset algorithm:
<<The angle of the Earth's axial tilt with respect to the orbital plane (the obliquity of the ecliptic) varies between 22.1° and 24.5°, over a cycle of about 41,000 years. The current tilt is 23.44°, roughly halfway between its extreme values. The tilt last reached its maximum in 8,700 BCE. It is now in the decreasing phase of its cycle, and will reach its minimum around the year 11,800 CE.[7] Increased tilt increases the amplitude of the seasonal cycle in insolation, providing more solar radiation in each hemisphere's summer and less in winter. However, these effects are not uniform everywhere on the Earth's surface. Increased tilt increases the total annual solar radiation at higher latitudes, and decreases the total closer to the equator.
The current trend of decreasing tilt, by itself, will promote milder seasons (warmer winters and colder summers), as well as an overall cooling trend. Because most of the planet's snow and ice lies at high latitude, decreasing tilt may encourage the termination of an interglacial period and the onset of a glacial period for two reasons: 1) there is less overall summer insolation, and, 2) there is less insolation at higher latitudes (which melts less of the previous winter's snow and ice)>>
Re: APOD: Sunrise Solstice over Stonehenge (2021 Jun 20)
Posted: Mon Jun 21, 2021 3:03 am
by WWW
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The picture was taken 13 years ago. How many times has this been used in APODs.
Also nice that they were able to rebuild the whole thing after that little tourist accident.
Click to play embedded YouTube video.
Re: APOD: Sunrise Solstice over Stonehenge (2021 Jun 20)
https://en.wikipedia.org/wiki/Griswold_family wrote:
<<The Griswold family originates from Solihull, England, where they lived for centuries as greyhound breeders, which were a favorite of King Edward I of England. During the colonial era, the Griswolds were one of a roughly half-dozen families which governed Connecticut state politics.
In 1801, the Hartford Courant called "Griswold" one of the most "revered and ancient families" of Connecticut.>>
<<Fort Griswold is a former American defensive fortification in Groton, Connecticut named after Deputy Governor Matthew Griswold. The fort played a key role in the early stages of the American Revolutionary War. Griswold defended the port of New London, Connecticut, a supply center for the Continental Army and friendly port for Connecticut-sanctioned privateers who attacked British ships. Construction of the fort was begun on December 5, 1775 in response to the outbreak of the American Revolutionary War. It was completed in 1778 and was located on a hill with the ability to bombard ships entering the Thames River.
In September 1781, British troops under Benedict Arnold raided and burned New London. The British were well informed of the layout of Fort Griswold, and Arnold approached the river from such an angle that its guns could not engage his fleet. The British forces divided, some to burn New London and the rest to attack the fort in the Battle of Groton Heights. The British eventually broke into the fort, and Colonel William Ledyard surrendered by handing his sword hilt-first to the commanding British officer—who took it and thrust it through Colonel Ledyard.>>
<<The Griswold Inn is located in Essex, Connecticut and is one of the oldest continuously run taverns in the United States. It was founded by three brothers in the late 18th century and named after the Griswold Family of the area. The inn was captured by British troops and used as a base of operations during the War of 1812. During prohibition, it still maintained a lively entertainment schedule for the local yachtsmen.
The Griswold Inn was also a filming location for the gothic soap opera Dark Shadows.>>
Sunrise Solstice over Stonehenge
