Sep 20

Sky Report September 21 – September 27

The seasons officially change at 7:31 am MDT on Tuesday, September 22, the autumn equinox, when summer ends and autumn begins. There’s nothing to see directly, but you do experience it in a sense: on the equinox the sun rises due east and sets due west and the days and nights are each 12 hours long. (“Equinox” comes from “equal night”, aequinoctium in Latin.) All summer the sun has risen and set north of east and west and the days were longer than the nights, but for the next six months this situation is reversed; the nights are longer than the days and the sun takes a more southernly path across the sky. It’s also the day when the sun crosses the earth’s equator; on this day, on the equator, the sun stands directly overhead at local noon. From the North Pole this is when the sun rises and from the South Pole it’s when the sun sets and there will be six months of continuous day and night respectively.

In the southern hemisphere the situation is reversed and it is their vernal equinox, and the beginning of their spring.

Turning to planets, the first “star” to appear tonight is the planet Jupiter, which is a third of the way up the southern sky as the sky grows dark and which is brighter than any real star. Saturn is a short distance (8°) to the left. These two planets remain paired the rest of the year, and they’ll be amazingly close late in December – coincidentally at the winter solstice. They’re at their highest and best at 9 pm and they set in the southwest after midnight.

The moon is to the lower right of Jupiter on the evening of Thursday the 24th and to the lower left of Saturn on the following evening.

Mars rises in the southeast at 9 pm and it’s precisely as bright as Jupiter. You can’t miss its red color which comes from rusted iron minerals in its surface rocks and soil. The earth is catching Mars as we orbit the sun faster and soon Mars will be slightly brighter than Jupiter. Mars will be in the news when it’s at its closest and is visible all night in just a few weeks.

Venus rises at 4 am and is brilliant low in the southeast during morning twilight. Telescopically Venus looks like a tiny two-thirds full moon.


The Sky Report is presented as a public service by the Stellar Vista Observatory, a nonprofit organization based in Kanab, Utah, which provides opportunities for people to observe, appreciate, and comprehend our starry night sky. Additional information is at www.stellarvistaobservatory.org. Send questions and comments to John@StargazingAdventures.org.

About the Author:

John Mosley
John Mosley was Program Supervisor of the Griffith Observatory in Los Angeles for 27 years and is the author of “Stargazing for Beginners” and “Stargazing with Binoculars and Telescopes”. He and his wife live in St. George where he continues to stargaze from his retirement home while serving on the advisory committee for Stellar Vista Observatory.

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