Welcome to Ontario Parks’ “Eyes in 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 best month of the year to enjoy the outdoors in Ontario.
The bugs are almost gone and daytime temperatures are cooler, making the weather ideal for strenuous activities like hiking or canoeing. To top it off, the leaves begin their beautiful transition through the colors of fall.
With much shorter days, the night skies are filled with celestial splendors that we hope you enjoy discovering in this edition of “Eyes in the Skies.”
Here are our astronomical highlights for September 2023:
The sun continues its apparent decline in elevation and we reach and pass the fall equinox at 2:50 a.m. on September 23.
On this day, the Sun appears directly above the Earth’s equator. Many people think that the amount of daylight and nightlight is equal on this day. While the numbers are very close, the day when we have equal day and night actually occurs a few days later, on September 25th.
The autumn equinox
The answer is interesting and most people don’t know it. It has to do with the way our atmosphere works and the way we mark sunrise and sunset.
First, our atmosphere bends light through a process known as refraction. That means that when we see the Sun appear at dawn, it is actually lower, still below the horizon. It’s just that Earth’s atmosphere has bent its light to make it appear higher and therefore visible to us.
The same effect occurs at sunset when the Sun has set below the horizon long before we see it disappear!
The second reason for the discrepancy between the date of the equinox and the equal date of day and night has to do with the size of the Sun.
We tell ourselves (logically) that sunrise occurs when we see the Sun for the first time and that sunset occurs when we can no longer see the last fleeting light of the Sun.
However, astronomers measure the Sun’s position not from its upper edge (as seen at sunrise or sunset), but from its center. Because the Sun is a certain size, it takes a few extra minutes from the time we see it at sunrise for the center of the Sun to clear the horizon.
And, of course, the opposite happens at sunset.
Due to both factors, we need a few more days in autumn so that the Sun rises later and sets earlier so that there are equal days and nights.
For those of us who rely on daylight to paddle to that distant lakeside campsite or hike that last ridge before settling in for the night, knowing when the sun sets is important.
Sunrise and sunset times
|September 1||September 15||September 30th|
|Sunrise||6:48 am||7:04 a.m.||7:22 a.m.|
The moon has long captivated observers of all ages. Even a small pair of binoculars will reveal the moon’s craters.
The lunar phases of the September moon occur as follows:
The planets – the return of Saturn and Jupiter
After almost nine months of absence, the planets Saturn and Jupiter are beginning to make their presence felt in the night sky.
At 10:30 p.m., Saturn is well situated, high in the south-southeast sky. Jupiter, slightly brighter than Saturn, starts low in the east at 10:30 p.m., but doesn’t rise in the sky until about 4:00 a.m.
He abroad The planets look best when they and the Earth are at the same level. same side of the Sun.
When a planet is directly opposite the Sun from Earth (visible in the south at midnight), it is known as opposition (from the word opposite).
Interestingly, just like seeing the full moon, when a planet’s opposition occurs in the summer, it appears very low in the sky because it follows the ecliptic and occupies the place that the Sun would occupy on the opposite side of summer (in other words , during winter, when the Sun is low).
When an opposition occurs around the winter solstice, the planet appears high in the sky because it occupies the position that the Sun would normally occupy in June.
Saturn just passed opposition in August and since it takes 30 years to orbit the Sun, it will still be another 10 years before it appears high in the sky again.
Jupiter, on the other hand, orbits the Sun in about 12 years and this year enters opposition on November 3rd.
As such, Jupiter is at its highest point we’ve seen in some time and is a marvel to behold. We’ll talk more about Jupiter in the October issue of Eyes on the Skies.
Comets, meteor showers and satellites
Observing meteorites, especially in the dark skies of our provincial parks, is one of the most fun ways to get started in astronomy.
You don’t need any special equipment other than your eyes!
An armchair, a sleeping bag and a friend are welcome to enjoy the show. If you take a look at our constellation maps, you can practice learning your constellations while observing meteors.
A meteor shower occurs when Earth enters the debris field of a comet that long ago passed around the sun.
These pieces of dust and sand, often no larger than your thumbnail, enter Earth’s atmosphere and burn up at high altitudes (see our blog on meteor showers for more information).
September is a relatively quiet month from a meteor shower perspective.
However, observers can always see sporadic meteors (random or unidentified showers) as they occur.
On any given night, in the dark skies of provincial parks, it is possible to see five to ten sporadic meteors per hour, especially after midnight.
In September, there are four meteor showers that produce only a few meteors each and that contribute to these “sporadic” observations:
- September epsilon Perseids
- Southern Taurids
- Geminid epsilon
In the featured constellations of August, we talk about Sagittarius, Capricorn and Delfino.
The September edition has water as its theme.
We talk about Pegasus, the flying horse (elk or baseball diamond), Aquarius, the water bearer, and Pisces Austrinus, the southern fish.