Campfire at night in winter

Eyes on the skies — December

Welcome to the Ontario Parks “Eyes on the Skies” series. This 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.

December brings some of the darkest skies of the year.

Take advantage of this great opportunity to go out into our parks. Breathe in the peace and solitude of December days and the bounty of the starlit skies.

Here are our astronomical highlights for December, 2020:

The sun

The sun completes its apparent southerly drop on the winter solstice on December 21 at 5:02 am.

In ancient times, people from many civilizations north of the equator were joyed with the cessation of the sun’s apparent southerly movement and celebrated the beginning of its northerly rise.

See our post from March to learn more about the solstices and equinoxes.

snowy sunset through trees

Sunrise and sunset times:

December 1 December 15 December 31
Sunrise 7:47 am 8:12 am 8:08 am
Midday 12:15 pm 12:21 pm 12:29 pm
Sunset 4:42 pm 4:41 pm 4:50 pm

The moon

The moon has long captivated observers of all ages.

December’s lunar phases are as follows:

  • Waning Gibbous on December 4
  • Last quarter on December 8
  • Waning crescent on December 11
  • New moon on December 14
  • Waxing crescent on December 18
  • First quarter on December 21
  • Waxing gibbous on December 26
  • Full moon on December 30

lunar phases

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?

Learn more here.

The planets — Mars, Jupiter, and Saturn

Mars continues to be a bright ruby-like star in the evening sky and is well placed high in the sky after sunset.

view of mars

After almost nine months of Saturn- and Jupiter-watching, these two planets are finally closing their evening gala (they’ll return in a few months to early-morning viewers at sunrise).

However, like many performers, they will leave us with a special encore event — a Great Conjunction.

A conjunction occurs when any two objects line up with each other as viewed from Earth. These objects can be planets, and our moon in combination with each other or with other interesting objects such as stars, nebulae, etc.

Conjunctions occur because Earth, moon, and other planets are in motion, which changes their relative angular distance to other objects in the sky.

See how Jupiter and Saturn are nicely lined up as viewed from Earth?

sky chart
Conjunction of Jupiter and Saturn on December 21, as seen from above the sun. Photo: SkySafari 6 Pro

All three planets are orbiting the sun in a counterclockwise direction as viewed from this vantage point.

Planets that are closer to the sun orbit faster. As a result, Jupiter is passing Saturn, and Earth is passing both of them even faster. This motion is what is leading to the December 21 “Great Conjunction.”

On the evening of December 21, the two planets will appear to be almost one object. They will be about 0.1 degrees apart, which is about the limit of resolution of the human eye for many people and about 1/6 of the diameter of the moon.

sky chart
View of the planets as seen in a telescope on December 21 from above the sun. Photo: SkySafari 6 Pro

In even a small telescope, viewers will have a great view of the planets and their numerous moons.

Note: you will need a very good view of the southwestern horizon. Any large trees, hills, etc. in that direction will surely block your view.

Meteor showers

December has two meteor showers to note: the Geminids and the Ursids.

meteor shower

The Geminid meteor shower, peaking on the night of December 13 into the morning of December 14, is one of the best annual meteor showers to see.

In any given year and under a moonless night, the Geminid meteor shower usually outperforms the much more famous Perseid shower in August. However, due to the cold temperatures and often cloudy skies of December, it is far less known.

However, this year, we are lucky in having a new moon phase near its peak and with its high number of possible meteors (150 per hour at best), this year could be quite a show!

The Ursid meteor shower peaks on the night of December 21, so if you are out watching the Great Conjunction, why not look up and see if you can see any meteors! Keep in mind that this is a fairly weak meteor shower, producing no more than 10 meteors per hour at best.

Featured constellations: Eridanus, Lepus and Monoceros

As we round out the year of constellations, we will focus on some of the fainter ones seen at this time of the year.

Map of the constellations

Learn about Eridanus, Lepus and Monoceros here.

This completes our review of the December skies…

Come back next month to learn about the calendar.