night sky

Eyes on the skies — September

Welcome to the Ontario Parks “Eyes on the skies” series. This series covers 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 2018:

The sun

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

Lake beside forest with leaves changing colours all under a blue sky with bright sun

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

Sunrise and sunset times

September 1 September 15 September 30
Sunrise 6:48 a.m. 7:04 a.m. 7:23 a.m.
Midday 1:26 p.m. 1:21 p.m. 1:16 p.m.
Sunset 7:53 p.m. 7:37 p.m. 7:08 p.m.

The moon

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

  • Last quarter on September 2
  • Waning crescent on September 5
  • New moon on September 9
  • Waxing cresent on September 14
  • First quarter on September 16
  • Waxing gibbous on September 21
  • Full moon on September 24
  • Waning gibbous on September 27

September moon phases

The planets

At long last, the spectacular planet showing we enjoyed all summer is coming to a close.

Venus sets at around the same time as the sun, rendering it pretty much invisible. Jupiter is visible after sunset only to those who have a good view of horizon, because it’s low in the sky. Saturn and Mars are still readily visible.

moon

To learn more about these planets, please visit our “Eyes on the skies — June” post (for Saturn) and “Looking up at Mars” article (for Mars).

Meteor showers

September is traditionally a quieter month for meteors.

Night sky

While there are no meteor showers peaking (concentrated activity in which you may see many meteors that originated from the same source), there are always sporadic meteors visible in the dark skies of our provincial parks.

Typically in September, between five and ten meteors can be seen, especially after midnight.

The amazing September night skies

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.

Positioning of the views of the night sky.

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.

Night sky with forest on the horizon

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

In August’s featured constellations, we discussed Sagittarius, Capricornus and Delphinus.

There is a water theme in September’s edition.

Diagram of September constellations.

We discuss Pegasus the flying horse (moose or baseball diamond), Aquarius the water bearer, and Piscis Austrinus the southern fish.

Did you know…

…the speeds of light and sound can provide us with a lot of useful information? That we can even apply when we’re camping? Read how we can apply this knowledge to stay safe when we’re camping in our post “Understanding the speeds of light and sound.”

This completes our review of the September skies. Come back next month to learn more about our galaxy and the stars of October.