What’s up in the sky June 07
You’ve read about it, visited archaeoastronomy sites and every year it is explained again. There have even been scenes in movies that have depicted the event, but now on June 21 you have the chance to observe it yourself. The summer solstice arrives at 1:06 p.m. CDT, the day that has no twin. If the shaft of sun light lit up your Idol March 21st, it would do it again September 23rd, but miss the summer solstice and you had to wait a year.
Eratosthenes noticed that the sun was directly overhead the city of Syene at mid summer. In 250 BC he performed his famous experiment to measure the circumference of the Earth. Assuming that Pythagoras theory that the Earth was round was correct. he erected a tall vertical pole at Syene ( now present-day Aswan) and one of equal length to the north at Alexandria. Observing the two poles at the Summer solstice the pole at Syene cast no shadow while the one in Alexandria cast a shadow that was 1/50 th of its length. Using geometry he measured the Earth’s circumference at 250,000 stadia, or in todays terms 25,000 miles. What he didn’t know was the Earth has an equatorial bulge and he was measuring polar circumference, but he was pretty close.
In northwest New Mexico is a land mark known as Fajada (banded) butte, located at the eastern end of Chaco Canyon. The canyon was settled as early as 1000 BC by Paleo-Indians. There was a distinct change of arcitecture between AD 700-900 and these people became the Anasazis.
On a cliff face of Fajada Butte about 33 feet from the top are three large upright rock slabs standing in front of a spiral petroglyph carved by the Chaco Anasazis. Sunlight comes between the slits and marks the equinoxes and the Summer and Winter Solstice. The Summer Solstice is the most spectacular, about eleven a.m. the sun appears as a dagger of light over the spiral and in about 20 minutes this dagger appears to split the spiral in two.
The Anasazis aren’t given much credit for their astromomy, they didn’t erect a Stonehenge, the rock slabs are an accidental alignment, You cannot predict when the Solstice will occur with the arrangement,and it doesn’t happen at dawn as it does in many other cultures, but they did make the spiral and it works.
To us June 21 will be a routine day. The TV weather man will comment on the Solstice and give its time of occurence with atomic precision, but once it was an event of awe and ceremony.
This month ;
June 1 Venus forms a horizonal line at dusk with Castor and Pollux in the west.
1-2 Mercury at greatest elongation, 23 deg east of the Sun.
Saturn and Venus close in on each other this month, Saturn moves from 23 deg on
the first to less than a degree on the 30th.
5 Jupiter is in the thirteenth sign of the Zodiac, Ophiuchus, at -2.6 mag. and it will be
45"-46" wide.
8 Venus at greatest elongation.
12-13 Venus near M44, the Beehive Cluster.
14 New Moon.
18 The dark limb of the Moon occults Venus, in the Middle East.
Venus moves toward Saturn.
19 The Moon will be 40" from the Alpha star of Leo Regulus.
21 Solstice occurs 1:06 pm CDT.
27-29 The Moon rising nearly full near the bright star Antares, and Jupiter.
30 Full Moon.
