Great Ideas Speaker Nights: Supernova 1987A

Zoom link: Meeting ID: 826 0823 4950 , Passcode: 212094

Supernovae are among the most violent events in the Universe since the Big Bang. They are highly destructive. And yet, they are also largely responsible for creating and dispersing most of the elements that enrich the Universe we live in. Indeed, without supernovae, the Earth and Life as we know them would likely not exist. On February 24, 1987, the brightest supernova since the invention of the telescope was discovered by a Canadian astronomer working on a mountaintop in Chile.

Join Dr. Ian Shelton for a personal account of his discovery of Supernova 1987A and efforts to find the elusive neutron star “beast” that created the explosion.

Zoom link: Meeting ID: 826 0823 4950 , Passcode: 212094

Tom Bolton (1943-2021 )

With heavy hearts, we report the passing of Professor Emeritus Tom Bolton earlier this week.

Tom is probably best known for providing the first definitive evidence showing that Cygnus X-1 is a black hole using the David Dunlap Observatory’s telescope. He was also instrumental in drafting the City of Richmond Hill’s landmark light pollution abatement bylaw.

As a close colleague of ours, he will dearly be missed.

Please take the time to watch this TVO Science Café episode where Tom -alongside other notable DDO astronomers – explains the history of the DDO and provides a tour of the 74″ telescope (circa 1990).

-DDO Defenders

What’s Up in December 2020?

If you would like to follow the exciting Astronomical Events in December,  please register to our upcoming Virtual Up In the Sky DDO program. Our expert astronomers will be teaching you how to navigate the night time sky.

Please visit to register and get more information about this program.

On December 21st Jupiter and Saturn will pass very close to each other, so close that you’ll need binoculars or a telescope to separate them. During the month of December these two gas giant planets can be seen just after sunset can be seen just above the south-west horizon. The attached video (animated GIF) shows how the two planets move each day during the month of December, then move apart after their closest approach on the 21st. Even if the weather doesn’t cooperate on the day of closest approach, it will be a fun sight to watch these two giant planets move each clear evening during the month of December.

-DDO Defenders 🙂

Mars in 2020

Every couple of years, Earth passes near to Mars. But because Mars’ orbit is quite elongated (“elliptical”), the distance between the two planets can get much closer every 15-17 years. This year was one of these closest approach years, with Mars just 62 million km away on October 6th. Ok, not close enough to ever worry about ever hitting Mars; but if you are in the business of sending spacecraft to other world, this is the best time to do so. And indeed, the US, China and the United Arab Emirates each launched their own mission to Mars this year, all expected to arrive there in February next year.  

Both planets, of course, are continuing to travel along their respective orbits about the Sun. As the Earth moves faster along its smaller inner orbit closer to the Sun, it overtakes Mars travelling in its more distant orbit, like race cars travelling along an oval racetrack. From our perspective here on Earth, as Earth overtakes Mars, Mars will be seen in the opposite direction from the Sun. Hence, we use the term “opposition” to describe these events. And if Mars is currently opposite the Sun, that means it rises in the East at sunset and will spend the whole night crossing the sky to set in the West at sunrise!   Mars continues to appear to the unaided eye as an unusually bright, orangey coloured “star” in the Eastern sky after sunset until the end of October. It will then begin to fade noticeably as the distance between the two planets steadily increases. Although it will rise earlier each night and stays high in the sky through the night, it will have dropped five-fold in brightness by Christmas time. So enjoy Mars now while it’s at its best! If you have a telescope, even a small telescope, this is your best opportunity to see Mars through your scope for the next 15 years!!! Here’s a sample of what our members have been able to achieve in 2020… 

-DDO Defenders 😁

The Orionids

The Orionids meteor shower peaks on the night of Tuesday October 20-21. This is a modest shower, producing about 20 meteors (“shooting stars”) per hour if you are viewing away from city light pollution. Of course, the sky needs to be clear. And expect to see less than half that number if you are observing from a moderately dark backyard in the suburbs. The crescent moon sets at around 9:30 pm on this night and so won’t spoil the view this year.  

It takes at least 15 minutes for your eyes to fully adjust to the dark so you can see the fainter meteors (…there are many more fainter meteors than bright ones). Turn off all yard lights and find a place that is shielded from seeing your neighbour’s lights or streetlights. Even looking at your phone’s display can cause you to lose your dark adaption and you will need another 15+ minutes in the dark to restore it. 

You will need to wait till about 10:30 pm EDT before any of these meteors will become visible. That is when the “radiant” for this shower rises above the Eastern horizon. If the sky is clear and you do indeed start your viewing right at 10:30 (till ~11:00 pm), you have a chance to catch an impressive “earth-skimmer” meteor, one that remains visible for a longer time as it streaks across a much longer path across the sky. 

To watch the Orionids or any other meteor shower, I strongly recommend you find yourself a fully reclining full length deck chair (Chaise Lounge) so you can be off of the ground and comfortably looking straight overhead without having to bend your neck. That is where you want to be looking, straight overhead to see the most meteors. The meteors will seem to be coming from a particular point in the sky, the shower’s “radiant”: whichever constellation the radiant lies in is how a meteor shower gets its name. In this case, the radiant lies in the constellation of Orion. But each meteor can be almost anywhere in the sky when it first lights up; and then it usually travels less than a quarter of the distance from horizon to horizon before it stops glowing.  

For those interested in knowing what an Orionid meteor is made of, you might be surprised to learn they are pieces of Comet Halley, which last passed by the Earth in 1986. Comets leave behind a trail of rock dust that fills the path they take as they orbit the Sun. Earth passes through that thin debris trail twice each year, producing the Orionid meteor shower in the Fall and the Eta Aquarids meteor shower in early May. 

-DDO Defenders 😄


Don’t wait till 2035 to see the next Great Opposition of Mars!

Image obtained by DDOD astronomer David Wing on September 4, 2020 from his home in Richmond Hill

Join us at our Mars Madness event starting October 3 for a chance to see Mars at its very best.

Mars imaged by the Hubble Space Telescope in 2003

Although Earth passes by Mars every couple of years, it’s only during rarer Great Opposition years like 2020 that the distance between the two planets is at its smallest, making Mars appear much larger when viewed through telescopes here on Earth.

We will provide views through telescopes, including the largest telescope in Canada. We will show you how to find Mars from your own backyard; You’ll learn fun facts and stories about Mars and its exploration. There will be special guests and lots of opportunities to ask questions. And there are fun activities. Best of all, you get to enjoy all of this from the comfort of your own home!

Space is limited, so don’t delay… Register today!

This event will be held on Oct 3rd, Oct 4th, Oct 5th & Oct 6th. Please follow the links to register.

DDO Restoration Update

Hi everyone,

Here are the latest photos from the David Dunlap Observatory Park. Restoration is still underway, and we definitely look forward to seeing a fresh coat of paint on all the domes!

Photos courtesy of Elaine Feig

-DDO Defenders

Penumbral Eclipse

On the evening of July 3rd, 2020, Richmond Hill resident Ian Shelton captured this image while watching the setting Sun beautifully illuminate the top of a huge distant storm cloud. When sunlight needs to travel horizontally through many additional thicknesses of our atmosphere to reach our eyes or a distant object like the cloud shown here, air molecules can scatter most of the blue sunlight out of the beam, leaving just the yellows, oranges and reds of sunlight to illuminate us or a distant cloud. Contrast this with the unfiltered white sunlight traveling directly through space to reach the Waxing Gibbous Moon seen above and ten thousand times further away than the terrestrial cloud top.

Two days later, Dr. Shelton was joined by several other member of the DDO Defenders to watch the now Full Moon pass into Earth’s shadow. Unlike a more familiar umbral lunar eclipse where a dark circular shadow makes part or all of a Full Moon seem to disappear, a penumbral eclipse is a much more subtle event that is easily missed. Encircling the cone-shaped dark inner “umbral” shadow cast by the Earth is the “penumbra”, a larger outer cone where only partial darkness occurs. On July 5th, the Moon passed 30% of the way into the penumbral cone, causing only about 20% darkening towards the north edge of the Moon.
  By eye, the event went unnoticed. But it was captured photographically, as shown in the image here. A photograph taken just before the eclipse began was subtracted from a photograph taken at mid-eclipse.

-DDO Defenders 🙂

Comet NEOWISE is Here!!

Hi Everyone,

Here is what Comet NEOWISE looked like this morning, July 8th, 2020 (via a camera, not by eye). The image was processed to increase the contrast and darken the sky, which was already getting pretty bright when the comet finally came out from behind the clouds at 4:30 am. The comet is likely going to remain an easy target for cameras on a tripod for the next week or two, as it moves further away from the Sun and closer to Earth. If the sky is clear, it should be visible by eye if you observe between ~4:00 and 4:30 am. Binoculars should reveal its stubby tail. The animation below shows where to look for the comet. And at 4:30 am on July 9th, 2020, the ISS will be seen passing through the same part of the sky (weather permitting). 

-DDO Defenders