Aug 28, 2018
by Tre Gibbs
By Tre Gibbs, L.A.A.S.
This month, we welcome the return of autumn in the Northern Hemisphere! The seasons are caused by a combination of:
1) Earth being tilted on its axis and
2) Earth orbiting the sun.
As the tilted Earth orbits the sun, there are times when the top half (northern hemisphere) is leaning toward the sun and receiving more daylight than night (summer) and times when it’s leaning away from the sun and receiving more night than daylight (winter). In between these two extremes, there are times when neither hemisphere is leaning toward nor away from the sun, and both hemispheres receive equal amounts of day and night. On September 22nd at 6:40 pm, Earth will be in this position and Fall will officially begin as we experience what’s known as the Autumnal Equinox. Equinox is a Latin word, roughly translated to mean “Equal Night” meaning, equal amounts of night.
Since we can’t travel out into space to view this event, we can experience it down here on Earth by watching where the sun rises and sets on this day. Going from summer to winter, the sun’s path in the sky has been gradually moving south. On June 21st, the longest day of the year, and the beginning of summer, the sun sets in the northwest. On December 21st, the shortest day of the year, and the beginning of winter, the sun sets in the southwest. On the Equinoxes, the sun sets right in the middle, perfectly west. Same with sunrise - but on the eastern horizon of course. After this day, the sun will rise and set just slightly south of due west, and it will keep heading south every day until early to mid-December, when it will appear to slow down, stop, turn around and head north again, continuing its annual cycle.
Back in early August, you may have noticed four planets in the sky at once, but only if you are one of the fortunate ones to have an unobstructed view of both the eastern and western horizon - in order from west to east; Venus, Jupiter, Saturn, and Mars. This month, Venus, in Virgo, continues her descent towards the glare of the sun, while Mars, in Capricornus the Sea Goat, rises earlier and earlier with each passing day. By the end of this month, Venus will be almost completely lost in the glare of the setting sun, with Jupiter, in Libra The Scales, close behind her. Saturn, much dimmer than the other visible planets and still in Sagittarius the Archer, shifts from the south-east to the south this month. The reason Saturn is so much fainter than the other planets is because it’s so far away from us - almost twice the distance of Jupiter - and there are even two more beyond Saturn, Uranus and Neptune, which are SO far away, you need a telescope to see them!
As always, the moon, in it’s monthly (or moonthly) orbit, pairs up with each planet over the course of its 28-day trek around Earth. Planet or “planeta”, is Latin for the word “wander”, since these bright lights mysteriously wandered through the same narrow path in the sky, as if they were deliberately being moved by The Gods…
On the 13th, look for the young crescent moon just to the right of bright Jupiter.
Four days later, on the 17th, look for the half moon to the right of Saturn.
Two days after that, on the 19th, look for the waxing (growing) gibbous moon almost right above bright and orange-ish Mars!
And speaking of the moon, on the 24th, we are treated to this month’s full moon, The Harvest Moon. The Harvest Moon is the full moon closest to the Autumnal Equinox and can occur in either September or October. This particular full moon allowed all the chores of harvest to get done - even after dark!
That’s it for this month, so enjoy the ever-changing cycle of the seasons and always remember to KEEP LOOKING UP!
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