Night sky.

Eyes on the skies – March

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

Sunrise

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.

Diagram showing seasonal rotation of earth around sun

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
Sunrise 7:04 7:38 7:07
Midday 12:38 13:34 13:29
Sunset 18:12 19:32 19:53

*We begin daylight savings time on the morning of Sunday, March 13, 2022.

The moon

The moon has long captivated observers of all ages. December’s lunar phases of the moon occur as follows:

lunar phases in march

The planets 

The bright planets are now all morning objects, visible before sunrise.

Of these planets, Venus presents the most splendour this month. For some time now, Venus has appeared as a bright morning object low in the southeast at sunrise.

On March 20, Venus will appear at its greatest distance away from the rising sun.

At that point it will be a brilliant object low in the south/southwest sky. Those who follow the changing motions in the sky know that the best time to observe Venus is during the spring, after sunset, and during the fall before sunrise.

But why?

Venus, like the Sun, moon, and the planets, follows the path of the ecliptic in the sky.

The ecliptic iswhat we call the path for the Sun’s motion in the sky around the Earth throughout the seasons (of course, it’s the Earth moving around the Sun and the obliqueness of our polar axis that causes the appearance of the ecliptic.).

You can estimate where the ecliptic is at any time of the year by thinking of the path the Sun takes.

For example, in the spring at sunset (when the Sun is due west) the path of the ecliptic rises from the position of the setting sun to a position even higher in the sky due overhead.

This is because during the summertime, the Sun would be at that position.

If we plot Venus’ best possible position along the ecliptic for each season at sunset, we can see that Venus appears highest above the horizon, in the best possible position to enjoy its splendour during the spring.

Comets and Meteor showers

Comet.

March is a quiet month from a meteor shower perspective. 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 provincial parks, one might see as many as five to 10 meteors per hour, especially after midnight.

March constellations

Constellation diagram

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.

This completes our review of March skies.