Welcome to the Ontario Parks “Eyes on the Skies” series. This space (see what we did there?) 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.
March is one of the most glorious months to be camping, or even just spend time outdoors enjoying our parks.
On March 20, the earth passes through Spring Equinox. This is the day that formally marks the beginning of spring and affords equal hours of sunlight and darkness.
Here are our astronomical highlights for March:
The sun reaches the Spring Equinox on March 20. Equinox can mean “equal” and “night.” Therefore, this is a time when we have equal amounts of day and night.
The earth’s many motions combine wonderfully to provide us with fascinating observations. We rotate along our axis, of which north is currently pointed towards Polaris, the North Star. We orbit around the sun in 365 and ¼ days, and the sun orbits around the center of our galaxy in just under 250 million years.
For the purposes of discussing the position of the sun in March and the Spring Equinox, let’s just focus on two of these motions: the rotation and orbit of the earth.
The diagram above shows the earth’s motion around the sun, as well as its rotation around its axis. Even though the earth moves continuously around the sun, the direction the axis points does not change, at least not over the course of a few years.
For observers in the northern hemisphere, we see the axis of the earth pointed towards Polaris the North Star. Light from the sun (represented by the orange arrows in the diagram above) hits the earth, and results in warming the whole planet. There is more focused heating in the area directly under the sun’s rays.
During the summer, because the northern hemisphere is pointed towards the sun at noon, there is more daylight hours and more direct heat for those in the north. In the winter, the situation is reversed, as the sun’s direct light is more focused on the southern hemisphere at noon, leaving the north with less light and less heat.
During the spring and fall equinoxes, the earth is positioned such that the sun’s direct light is over the equator, right in between the northern and southern hemispheres. During this time, we have equal amount of light and darkness, and moderate temperatures. The equinoxes are important markers of seasonal change.
Here are our sunset and sunrise times for March:
|March 1||March 15||March 31|
*We begin daylight savings time on the morning of Sunday, March 14, 2021.
The moon has long captivated observers of all ages. December’s lunar phases of the moon occur as follows:
Did you know many First Nations teachings, including those of the Anishinaabe and the Haudenosaunee people, use the back of a turtle’s shell as a lunar calendar?
The planets – Mars, Jupiter and Saturn
Mars is still relatively high up in the west at sunset. The other planets are beginning to make an appearance early in the morning sky. Saturn, Jupiter and Mercury are all fairly close together and rise about an hour before the sun does.
Comets and Meteor showers
March is generally a quiet month for meteor observing. Our next good meteor shower is the Lyrids, which peak in late April.
Nevertheless, observers are always able to see sporadic (random or unidentified shower) meteors as they may occur. On any given night in the dark skies of our Ontario Parks, one might see as many as five to 10 meteors per hour, especially after midnight.
The Orion Nebula – a stellar nursery beckons your gaze
The popular constellation, Orion the Hunter, is one of the best constellations to see from the city and is one of those few western constellations that actually does look like its namesake.
While this constellation is thought of as a winter season pattern, its actually can be well seen in March just after twilight high in the south to southeast.
Under the “belt of Orion” (see drawing), lies an incredible object that is visible to even city dwellers with binoculars — the Orion Nebula (M42). To find the Orion Nebula, find the belt of Orion and then his sword (directly underneath). For an observer without optical aid, the sword looks like three vertical stars. The middle star is actually the location of the Nebula itself.
To those with a good view, binoculars can show the foggy or nebulous cloud-looking feature.
Usually, if your sky is dark and your vision good, you may even see some green colour to the nebula.
In a large telescope, like Killarney Provincial Park’s larger observatory — Gche Waasa Debabing — the Orion Nebula can display many of its incredible splendours.
This nebula is a perfect example of the richness of space and helps us to understand the formation of stars.
The interstellar gas cloud is rich in hydrogen and other materials. Young hot stars pour out ultraviolet radiation upon the hydrogen gas, ionizing it and cause it to emit light — similar to the principal that causes a neon sign to glow. The light from the emission looks red to our eyes and in the picture above.
At the same time there is a lot of light reflected to us and that light shows up as blue.
Finally, there is a fair amount of interstellar dust between us and some of the light parts of the nebula. This shows up as dark cloud against the lighter backdrop. This is a great example of an emission nebula, reflection nebula, and dark nebula all combined into one!
If we zoom into the centre of the Orion Nebula, we can see a small grouping of stars known as “the Trapezium.” This grouping of stars formed from the gas in the Orion Nebula and is only 300,000 years old! An infant in the cosmic timescale.
Stars form when interstellar gas clouds, such as the Orion Nebula, are affected by forces, such as the collision with another gas cloud or from the impact of a supernova shock wave.
The compression that occurs causes the gas to form eddies and swirls and those eventually condense into massive spherical balls of gas. These balls of gas experience gravitational forces directly related to the amount of mass. The more mass, the more gravity. The more gravity, the more of the surrounding gas cloud is attracted to the gas ball which brings in more gas mass.
This cycle continues in a positive loop causing the gas ball to get bigger and bigger. What’s important is that, as mass builds up, the higher gravity compresses the central core of the gas ball heating it up tremendously.
Once these balls of gas become massive enough to produce sufficient gravity to heat the core to 15 million degrees, the gas ball’s core is hot enough for thermonuclear fusion to commence — a star is born. In the case of the Orion Nebula, many stars are formed, some of which make up the trapezium that we see today.
In last month’s blog, we discussed Gemini the Twins, as well as two other prominent constellations seen in the winter.
This month’s post will focus on three constellations that mark the transition from winter to spring: Leo the Lion, Cancer the Crab, and Coma Berenices.