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 just outdoors, enjoying our parks. On March 20, the earth passes through Spring Equinox, the day that formally marks the beginning of spring and affords equal hours of sunlight and darkness.
Here are our astronomical highlights for March 2017:
The position of the sun
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 that the axis points towards 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 but there is more focused heating the area directly under the sun’s rays.
During the summer, because the northern hemisphere is pointed towards the sun at noon, there are 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 (“equinox” can mean “equal” and “night”), 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.
Moon, planets and other phenomena
The phases of the moon for March occur on almost the exact same dates as they did in February because the duration of February is about the same length as the time it takes for the moon to orbit the earth.
March evening phases of the moon occur as follows:
- waxing crescent on March 2
- first quarter on March 4
- waxing gibbous on March 8
- full moon on March 12
The lady in the moon
As promised in last month’s “Eyes on the Skies,” this month’s lunar update will feature the “lady on the moon.” Many people have commented on different types of people or animals that they see on the face of the moon. One of the clearer figures is that of a lady in the moon. When one of our many astronomy presenters was showing the lady in the moon to an audience, a younger participant in attendance commented that she looked an awful lot like Wilma Flintstone.
Once you see Wilma, you will never forget her again:
Venus and Mars continue to be visible in the night sky. Venus, which has been the brilliant “Evening Star” for the past few months now, disappears by the end of the month and begins to become only visible in the morning (hence the “Morning Star”). So as we say goodbye to Venus, let’s talk at little bit more about the planet.
Venus, named for the Roman goddess of beauty, is one of the most beautiful objects that can be seen without a telescope in the night sky. It sometimes appears well placed in the evening sky and sometimes well placed in the morning sky. Interestingly, many ancient cultures did not connect these two appearances as being the same object and referred to them as different objects (“morning star” and “evening star”).
This photo shows Venus as seen through a telescope at the Killarney Provincial Park Observatory. No detail can be seen because Venus is completely shrouded in clouds. This photo illustrates how that Venus goes through phases as it orbits the sun. Galileo first discovered this in the early 1600s using his very primitive optic tube (telescope).
Venus is remarkably similar to Earth in many ways: it comes closer to the earth then any other planet, it is about the same size as the earth, and it is a rocky world that has a thick atmosphere.
However, Venus’ thick atmosphere is made of over 90% carbon dioxide (CO2). This well-known greenhouse gas permits light from the Sun to reach the surface of Venus and warm it up. But very little of the warmth is able to escape back out into space because the CO2 traps it, like panes of glass preserve heat in a greenhouse. As a result, Venus, not Mercury, is the hottest planet in our solar system with average temperatures in around 460 degrees Celsius.
In fact, it was the discovery of this “greenhouse effect” on Venus by Carl Sagan that first alerted the scientific community to the potential dangers of climate change on our own planet.
Featured constellation: Leo the Lion
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 the mark the transition from winter to spring: Leo the Lion, Cancer the Crab, and Coma Berenices.
Leo the Lion
High in the south at this time of the year, we find Leo the Lion. To find Leo, look for a backwards question mark and, to its left, a triangle with the long part facing towards your left (east). Leo’s head and mane are formed by that question mark and his body reaches towards the triangle.
Can’t quite see it? Mouse over the image below to see a cat superimposed over the stars of Leo.
Regulus, the brightest star in Leo, is a multiple star system (four stars in orbit around one another) of which two can be seen in a telescope. Regulus means “little king” and is one of the four royal stars of ancient times. The others are Antares (summer), Aldebaran (winter), and Formalhaut (fall).
Cancer the Crab
To the west of Leo is Cancer the Crab. A few inconspicuous stars form the body of the crab. Within Cancer, one can find an open cluster known as M44 – the Beehive Cluster.
As described in last month’s edition, an open cluster is a loose grouping of stars that have all formed together from a giant gas cloud. While the cloud may have dissipated, the leftover stars can still be seen. Open clusters can be spotted in park skies with binoculars, and look fabulous in a telescope.
Coma Berenices (Queen Berenices Hair)
To the left (east) of Leo is the constellation of Coma Berenices, named after Queen Berenices II (Queen of Egypt during the Ptolemaic Dynasty). It is the only constellation that is named after a historical figure.
This constellation, made up of many loose stars that represent the hair that she cut off and sacrificed as a votive offering. Interestingly, her hair is actually an open star cluster in its own right, but was not recognized because of its large size.
The Aurora Borealis (Northern Lights)
The spring and fall equinoxes tend to be good times to view the Northern Lights (known as the Arsaniit in Inuktitut). This magical glow occurs when charged particles emanating from the sun along the solar wind interact with the earth’s magnetic field. When large amount of charged particles are involved, the earth’s magnetic field can become so compressed on its sunward side that it is no longer capable of deflecting all the material away from our atmosphere. Instead, the material can collide into our atmosphere, charging up the molecules of air much like a neon sign.
Usually, when the sun is particularly active (the sun has an 11 year cycle of high and low activity), more material breaks free out into space (and sometimes towards the earth). Unfortunately, we are nearing the low point of activity (solar minimum) and it is unlikely (though not impossible) we will see good displays of Northern Lights this year from our latitudes.
Get your eyes on the skies this month
Remember to bundle up and enjoy the view from our parks. The stars await those who make the effort to enjoy them.