Greetings everyone and welcome to autumn! Autumn officially began yesterday, the 23rd. Of course, the leaves won’t start turning colors and falling off the trees here, nor will the weather grow noticeably colder. That’s one of the many wonderful things about the tropics.
Virtually the only effect of the changing seasons here is the changing day length.
It’s not as noticeable as it is in the temperate zones (where you can lose two hours of daylight in three weeks) but the day length does change.
As I mentioned earlier in the month, we’ll lose 20 minutes of evening daylight in September and no morning daylight at all, since sunrise will be at 6:10 am every day in September.
Yesterday was the autumnal equinox and of course equinox means “equal night.” Not here though. On Friday, the sun rose at 6:10 am and set at 6:17 am
So don’t worry that you’ve missed the equinox because ours doesn’t happen until the second and third of October when the sun rises and sets at 6:10 am
But what happened yesterday is that the sun rose due east and set due west. However, the sun doesn’t move very fast along the horizon so you can still find due west if you watch the sunset tonight.
Although Venus has disappeared from our early morning sky, Mars will still be overhead, and Jupiter will be close to the western horizon.
You can also see Jupiter in the early evening eastern sky a fist-width above the eastern horizon at 7:20 pm. Saturn is four fist-widths to the right of Jupiter and three fist-widths up.
Don’t look for Mercury in either the morning or evening sky, however. The solar system speed demon passed between us and the sun yesterday and will reappear in the early morning sky next month.
After you watch the sunset and find due west, turn 90 degrees to your left and face south and you’ll see Scorpius the Scorpion. The Scorpion’s body is horizontal above the southwestern horizon.
Above the Scorpion’s tail is the teapot asterism of Sagittarius the Archer and the easternmost stars of the teapot’s handle are due south this week.
Measure two fist-widths down from those stars and one fist-width to the left and you’ll see a fairly bright star that may be flashing brilliant colors.
All bright stars flash the colors of the rainbow here when they’re close to the horizon because we have so much water in our air that it breaks the star’s light into the colors of the rainbow, but that particular bright star has an interesting name.
That’s the Peacock Star, the brightest star in the constellation Pavo the Peacock, one of our many southern birds.
The Peacock Star is the Peacock’s tail, and you may be able to make out the triangle of its head a fist-width to the right and closer to the horizon.
Its body is made of faint stars that are very close to the horizon and you might not be able to see them.
Two fist-widths down from Saturn, you’ll see a bright star. That’s Fomalhaut the 18th brightest star. Although it’s not part of a bird (it’s the brightest star in Piscis Austrinus the Southern Fish) it’s pretty easy to find.
Enjoy your personal sky tonight!
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 [email protected] and we will forward them to her.