Stars in the night sky.

Eyes on the skies — September, 2017

Welcome to the Ontario Parks “Eyes on the Skies” series. This will cover a wide range of astronomy topics with a focus on what can be seen from the pristine skies found in our provincial parks.

Many people consider September to be the finest month of the year to enjoy Ontario’s outdoors.

The bugs have all but left and the daytime temperatures are cooler, making the weather ideal for strenuous activities such as hiking or canoeing. To top it off, the leaves begin their beautiful transition through the colours of fall.

With the much shorter days, the nighttime skies are full of celestial splendors that we hope you will enjoy discovering in this edition of Eyes on the Skies.

Here are our astronomical highlights for September 2017:

The sun

The sun passes through the fall equinox on September 22. On this day, we have an equal amount of daylight and night.

Check out our March edition to learn more about the Earth’s orbit around the sun.

The moon

September’s lunar phases of the moon occur as follows:

  • Waxing gibbous on September 2
  • Full moon on September 6
  • Waning gibbous on September 9
  • Last quarter on September 13
  • Waning crescent on September 16
  • New moon on September 20
  • Waxing crescent on September 24
  • First quarter on September 28

Phases of the moon.

The planets

There are two planets prominently on display this summer.

Jupiter, discussed in our May edition, is high up in the constellation of Virgo (near Spica) at sunset.

Saturn, discussed in our July edition, can be found low in the south near the border of Ophiuchus, Scorpius and Sagittarius around midnight.

The amazing September night skies

Positioning of the views of the night sky.

One of the most interesting things about observing the stars in September is that if you stay up all night you can see many of the constellations from the summer, fall, and even the winter skies.

Even more, for a good few weeks the summer triangle stays right above us at sunset each night!

How can this be? The apparent standstill of the summer constellations during September is somewhat of an illusion.

As the earth swings around the Sun, we are presented with a slightly different view of the stars each night. This is what explains the apparent westward drift of the constellations.

If you were to look up at midnight on successive nights, you would see that the constellations have shifted a little to the west. The constellations you see tonight at midnight would have been in the exact same position at four minutes to midnight the day before, and will be in the same position four minutes after midnight the day after. Astronomers say the constellations have moved by four minutes to the west on each night.

For a while in September, the sun sets about four minutes earlier each night. So, because the constellations seem to move about four minutes’ worth of distance per night to the west AND the sun is setting four minutes earlier, we see the same constellations at sunset each night for most of the month

Featured constellations

Diagram of September constellations.

In last month’s edition of Eyes on the Skies, we discussed Sagittarius, Capricornus and Delphinus.

In this month’s edition, we will discuss Pegasus the flying horse (moose or baseball diamond), Aquarius the water bearer, and Piscis Austrinus the southern fish.

Pegasus the flying horse (moose or baseball diamond)

Diagram of Pegasus constellation.

As we move into the fall, we see one very large and prominent constellation officially known as Pegasus the flying horse.

To the Anishinaabe people, this region was known as the moose. Moose are incredibly strong animals, well-adapted to their environment, and are held in high regard.

Our celestial moose is well displayed, even including the noticeable fur underneath its chin. Faint stars mark out the front of the antlers, and other stars make out the body and legs.

Having a moose in this section of the sky suits our fall water theme with a water bearer and fish. To learn more about Anishinaabe sky stories, one may refer to such books as “Ojibwe Sky Star Map” by Annette Sharon Lee and William Peter Wilson.

Diagram of baseball diamond constellation.

Pegasus can also be seen as a baseball diamond. In this case we have two stars for the pitcher and ball, two stars for the batter and bat, and a star for the catcher. Three other stars mark out the bases.

During an astronomy night in one of our provincial parks, visitors were thrilled to see a home run batted out of this baseball diamond! A meteor shot out from the “home base” star just as the presenter finished describing the constellation.

Diagram of Moose constellation.

The classical form of Pegasus is in the form of a flying horse. This is one of the few constellations that does indeed look like a horse, even if that horse is upside down.

While there aren’t any wings on this horse, the ancient Greeks associated it with Pegasus the flying horse who was born from the body of Medusa.

Interestingly, in keeping with the water theme this month, “Pegai” in Greek can mean “the waters.” The horse is said to have caused water to come forth after hitting the ground with his hoof.

Up and to the right of the horse’s muzzle, we find a globular star cluster – M15. This is perhaps one of the best clusters found in the autumn skies.

Aquarius the water bearer

Diagram of Aquarius constellation.

The next constellation on our night sky tour this month is Aquarius the water bearer. This is one of those constellations which is really hard to see as a person carrying water.

Aquarius represents the young boy Ganymede, who was seconded into providing the “nectar of the Gods” to the Olympians. Off of his left shoulder is the globular star cluster M2.

Piscis Austrinus the southern fish

Diagram of southern fish constellation.

The last of our constellations for September is Piscis Austrinus, or the southern fish.

In this case, the constellation does not show two fish as in the much more popular Pisces. Instead, it’s a solitary fish, which may be the parent of the two Pisces fish.

What gives Piscis Austrinus some distinction is the star Fomalhaut, the brightest of the autumn stars. Fomalhaut is a star that lies 25 light years away from us, and is somewhat more powerful than our sun. Fomalhaut has several debris disks leftover from its formation.

In 2008, an image taken by NASA’s Hubble Space Telescope provided the first glimpse of an extrasolar planet, meaning a planet beyond our solar system (see image below).

Diagram of Fomalhaut System showing extrasolar planet.

Meteor showers

The Southern Taurid meteor shower peaks on the night of October 9, however as many as 15 a night may be seen in dark skies, especially after 1:00 am.

When watching for meteor showers look for slow moving dashes of light coming from the east.

This completes our review of the September skies…

Come back next month to learn about the best constellations of October.