The summer solstice marks longest day of year
As you were sleeping, the Earth moved to another key position around the sun, with the annual arrival of the summer solstice.
That occurred in Arizona at 2:13 a.m. on Tuesday.
While in a dark sky, the sun was moving into the zodiac sign of Gemini as we awaited the first full day of summer 2022. The sun rose at 5:19 a.m., one of the earliest of all sunrise times of the year in Phoenix.
The longest day of the year came in at total of 14 hours, 22 minutes and 17 seconds of daylight. The sun will set at the latest time of 7:42 p.m., until the end of the month.
As if we needed the extra daylight with the oppressive summer heat in Arizona, the story which surrounds the summer solstice is most interesting.
The Earth has a few lines of demarcation on the globe. They are the equator, the Tropic of Cancer, the Tropic of Capricorn and the Arctic and Antarctic circles.
To get a better understanding of the summer solstice, we look to the Tropic of Cancer, located at 23 degrees 26 minutes and 10.9 seconds of arc in latitude.
At the moment of the summer solstice, the sun would appear at the overhead point or zenith in the sky at noon local time.
The motion of the Earth around the sun is not constant and the tilt of the planet can range from 22.1 degrees to 24.5 degrees on its axis. This is due to a phenomenon known as precession.
Here is some additional material on the Tropic of Cancer.
Over time, there is a drift of the Tropic of Cancer to the south. The annual drift in declination of the Earth is some 49 feet to the south each year.
This is due to the long-term precession of the Earth on its axis.
Here is a detailed explanation of Earth precession.
The term “Tropic of Cancer” is old and comes from a time when the sun was in the constellation of Cancer the crab at the start of the summer solstice.
The word “solstice” comes from the Latin term “too stand still,” for when the sun reached its high point on the ecliptic path.
The solstice is a celebration of the birth of the sun in our skies and many civilizations have paid homage to the event.
The most famous of all sun monuments on Earth has to be Stonehenge.
This ancient rock formation is like a time machine on Earth.
Learn more about Stonehenge here.
For us here in Arizona, it is a great time to explore the late evening summer skies as we move towards some of the shortest nights, with true dark only lasting some 6.18 hours in the Phoenix area.
The new season of summer will last for the next 93 days or so.
Enjoy our Arizona night skies before the summer monsoon sets in and happy summer!
To print your own monthly star chart, click here.
To view satellites/dates/times of passage, click here.
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Podcasts are available here.