Greetings everyone and welcome to another season-changing month. We’re lucky here in the tropics. We’re close enough to the equator that we don’t really have seasons, except for rainy and dry.
And the seasons don’t change our day length much. The farther north or south you go away from the equator, the longer and shorter the days and nights become.
In far northern summer, the days are incredibly long and the nights incredibly short. Above the Artic Circle, the sun never sets in the summer.
Of course, it never rises in the winter and it’s dark all the time. Not my idea of a good time. But our day lengths do seasonally change here in the tropics. They just do it in a strange fashion.
Autumnal equinox
Autumnal equinox is this month when day and night lengths are equal. But not exactly here.
Although the equinox is on the 23rd of September, our equal days don’t happen then. I’ll tell you all about it later in the month.
We lost 16 minutes of evening daylight in August, and we’ll lose 20 minutes in September. And since the days are getting shorter, we probably lost a lot of morning daylight too, right?
Well, we lost 4 minutes of morning daylight in August and last Monday, the 29th of August, the sun rose at 6:10 a.m. But here’s the strange thing. The sun will continue to rise at 6:10 a.m. for the entire month of September.
The sun won’t start rising later until early October!
You can still see all five visible planets. Venus, Jupiter and Mars are in the early morning sky. Venus is close to the eastern horizon; Mars is almost straight overhead and Jupiter is four fist-widths above the western horizon.
If you watch one of our magnificent sunsets this week you might still be able to spot Mercury in the evening sky, close to the western horizon as it grows dark.
Turn completely around at 7:30 p.m. (that’s one hour after sunset) and Saturn will be two and half fist-widths to the right of due east and two and half fist-widths above the horizon. And of course, if you want to see six planets, just look down.
After you find Saturn, turn 90 degrees to your right, face south and wave goodbye to Alpha and Beta Centauri, the third and 10th brightest stars. Alpha Centauri is on the left and it’s so bright because it’s the closest star to our sun. So, wave goodbye to the neighbor!
Turn completely around and you’ll see that the Big Dipper is also nearing the northwestern horizon. The bowl will disappear in September and the entire constellation will be gone by the end of October.
But there are always wonders to see in Guam’s skies. A horse will fly into your personal sky in September as will most of the players in a famous Greek legend.
And although we’ll lose Mercury, another planet will enter the early evening sky in September. Can you guess which one?
Our location in the tropics makes for some really astounding sky watching. Don’t miss a single Starry Starry Night and I’ll tell you all about it!
Pam Eastlick was the coordinator for the former University of Guam planetarium since the early 1990s. She has been writing this weekly astronomy column since 2003. Send any questions or comments to life@guampdn.com and we will forward them to her.
