stars above Killarney

Eyes on the skies — May

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.

While spring “technically” begins in March, most of us living in cold climates tend to celebrate May as the true start to the season.

The lakes open to allow the first paddle strokes, and the songs of migratory birds can be heard throughout the land. Staying up through twilight lets you see the splendors of the evening sky whilst being serenaded by the lovely sound of Spring Peepers and Chorus Frogs.

Here are our astronomical highlights for May, 2019:

The sun

The sun, having passed the spring equinox, continues to rise (and set) further north of due east (and due west). And, as usual, when the sun appears more northerly in the sky, the full moon that month appears almost equally further south.

a round sun setting in the orange sky over a dark horizon

Sunrise and sunset times: 

May 1 May 15 May 30
Sunrise 6:14 am 5:55 am 5:40 am
Midday 1:23 pm 1:22 pm 1:24 pm
Sunset 8:32 pm 8:50 pm 9:07 pm

The moon

While most people appreciate the beautiful red colour of a sunrise/sunset, fewer remark on a moonrise/moonset. As evident in this photo, the moon can be reddened by viewing it through the thicker atmosphere that exists as one looks through towards the horizon.


The moon is our closest neighbour in space, and is currently thought to be the residue of a collision between Earth and a smaller, Mars-sized object that occurred early on in our solar system’s history. The resulting explosion would have thrown much debris into space, possibly forming a rocky ring around the early Earth. Over time, the ring material would have grouped up into what we now see as the moon.

While the moon would have formed fairly close to the earth, the passage of time has seen a slow drift away. As well, the moon’s rotation rate has slowed considerably, becoming “tidally locked” to the earth. The moon’s rotation rate equals that of its orbital rate and it is this orbital rate that affects the duration between its phases.

May’s lunar phases occur as follows:

lunar calendar in may

We’ve known for thousands of years that depending where you lived, you usually experienced an increase in the height of the seas/oceans around full or new moon phases. Did you know that our landlocked province also experiences the effects of tides?

Get a crash course in tides here.

The planets

Venus sets an hour or so after sunset in the west northwest. Mars and Saturn rise later in the early hours of the morning.

Jupiter rises around the same time that Venus sets and stays up most of the night. It reaches opposition (the point in which its directly opposite the Sun) on May 8 and, as a result, will be as close as the planet typically gets.

Jupiter is by far the largest planet in our solar system. At just over 140,000 km across, you could actually place all of the other planets combined within Jupiter’s massive bulk. And, if you were to hollow out Jupiter (like a pumpkin), you could fit over 1,000 Earths inside it!


Jupiter is the poster child for a class of planets known as “Gas Giant” worlds. These planets share four basic things in common. They are all:

  • much larger than the Earth
  • have many satellites (moons) – Jupiter has 67 moon at last count
  • mostly made up of gas
  • located in the outer portion of our solar system

Jupiter, despite its tremendous size and bulk, has the fastest rotation rate. Whereas a day on Earth is 24 hours long, a day is just under 10 hours on Jupiter. This rapid rotation rate, combined with its gaseous composition, causes Jupiter’s atmosphere to form amazing patterns: belts, swirls, eddies and at least one giant red spot that has been seen for over 300 years.

The “Red Spot” (lower left in the above picture) is an intense area of high pressure (like a hurricane in reverse) known as an “anti-cyclonic disturbance.” The Red Spot alone could fit between two or three Earths inside it.

While Jupiter has many satellites, there are four that are especially easy to see and were discovered by Galileo more than 400 years ago; hence known as the Galilean moons. These moons are tidally locked to Jupiter and orbit around it in just under 10 hours. As such, the moons (which are very easy to see in a pair of binoculars) take on different patterns that noticeably change throughout the course of the night.


In this picture, Jupiter is seen with Io (at left) and Ganymede (at right). Also note that the Great Red Spot has rotated towards the lower right in the picture below as compared to the lower left in the picture above.

Trailing behind Jupiter is the planet Saturn, of which we will discuss more in next month’s edition.

night sky
Photo: SkySafari 6 Pro

On the morning of May 25, these two planets (Jupiter is the brightest object on the right) plus a last quarter moon make a nice display in the east around 4:00 am.

Featured constellations

In last month’s post, we featured the Ursa Major, the Great Bear (Big Dipper) and Ursa Minor, the Little Bear (Little Dipper). In this month’s edition, we will talk about constellations that are ideal for warm weather observation, Bootes the Herdsman, Virgo the Maiden and Libra the Scales. 


For more information on this month’s constellations, click here.

Meteor showers

On the night of May 6 into the morning of May 7, observers can see meteors coming from the constellation of Aquarius. In dark skies, observers should see about 20 meteors per hour or so. The good news is that many of these meteors are actually quite bright.

night sky

As always, the best way to prepare for a meteor shower is to get lots of rest, use sunglasses for at least three days prior to the shower (to maximize your eyes’ night vision capability), set up a lounge chair and a sleeping bag (use some sort of dew cover or your bag will end up quite wet), get lots of drink and munchies and, best of all, enjoy the experience with some good companionship.

Did you know…

…the habitable zone of a solar system is the range of distance from sun that is not too hot, not too cold, but just right for life? It’s also known as the Goldilocks Zone!

For many decades, astrobiologists have been studying and developing models for how life can form on other planets. They look at a wide number of factors including temperature, pressure, moisture, chemical composition, stellar radiation (e.g. effects of ultraviolet light) and more. The Goldilocks Zone represents a habitable zone that surrounds any star and has the right conditions to allow for liquid water (between 0ºC and 100ºC).

For more information on habitable zones, visit this post.

This completes our review of May skies…

Remember, you can explore our parks day and night, and the stars await those who make the effort to enjoy them!