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, 2018:

The sun

The sun completes its apparent southerly drop on the winter solstice on December 21 at 11:28 a.m. To great celebration, it then begins 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 a.m. 8:00 a.m. 8:07 a.m.
Midday 12:15 p.m. 12:21 p.m. 12:29 p.m.
Sunset 4:42 p.m. 4:41 p.m. 4:50 p.m.

The moon

December’s lunar phases are as follows:

December 2018 lunar phases

The planets

Mars is visible in the south at sunset. While not nearly as bright as it was in the summer, it is still a beautiful reddish object.

Mars and moon as seens through telescope and binoculars
Sky chart images Courtesy of SkySafari 6 Pro

On the night of December 14, look to see the moon and Mars appear close to each other in the sky.

Meteor showers

The best meteor shower of the year – the Geminid Meteors – peaks on the night of December 13/14, around 2:00 in the morning.

Night sky

While many people are familiar with the Perseid Meteor Shower, it is actually the Geminids that tend to put on the best show. These meteors tend to be bright and medium speed, and are an amazing sight if you have good weather (and if you are not freezing).

So bundle up and enjoy the view (a good article about observing meteors can be found here).

Comet 46P/Wirtanen 

Comet 46P/Wirtanen comes closest to Earth on December 16, just two days after the Geminid Meteor Shower.

Comet 46P Wirtanen
Sky chart images Courtesy of SkySafari 6 Pro

While news articles rave that this is the brightest comet of 2018, it will be very hard to see from urban and some rural environments unless you have a telescope.

comet nucleus
Nucleus of Comet 67P/ Churyumov-Gerasimenko: Photo: ESA/Rosetta/NAVCAM

From truly dark skies, (such as our two dark-sky preserves: Killarney and Lake Superior Provincial Parks), the comet will be visible as a very faint smudge, perhaps about the size of the full moon.

Even though the nucleus of the comet is quite small (less than 10 km across), it appears quite large in the sky because if enough material has evaporated away, we can see the “coma,” or region of gas and debris that surrounds the nucleus.

coma of comet holmes
The coma of Comet Holmes. Note: the small star-like dot near the center of the coma is actually the nucleus of this comet.
Photo: NASA / JPL-Caltech / W. Reach (SSC-Caltech)

The coma can actually stretch out to 80,000 km or so but it is quite diffuse, meaning that the light is very spread out and not brightly concentrated.

If you are fortunate to be able to look at the comet from a telescope that can track it, you will note that, over the course of the night, the comet has appeared to move against the backdrop of stars. It is the nightly movement that astronomers watch for when discovering new comets.

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.