Walking Among Giants

In July of this year, NASA’s Juno spacecraft successfully completed its five-year primary mission to explore and better understand the hidden internal structure of Jupiter, the largest planet in our Solar System. Based on what we know about Jupiter’s chemical composition, researchers have been looking at Jupiter to help them advance their theories about what happens to ordinary matter when pushed to incredibly high pressures and densities that remain unobtainable in laboratories here on Earth. Jupiter may be showing us the way towards creating room-temperature superconductors made out of the ordinary and plentiful element hydrogen.

Join us for a review of what we have learned so far, and what we hope to discover as Juno embarks upon a five-year extension to its mission.

Following the talk, participants can enjoy live virtual close-up views of the planets Jupiter and Saturn, as weather permits.

The Presentation will also provide you with a report on the Perseids Meteor Shower and information about viewing naked-eye nova RS Ophiuchus that erupted on August 8th

-DDO Defenders ?

GTA Skies: The Perseids Meteor Shower

The Perseids meteor shower peaks this week on Wednesday and Thursday nights (August 11th & 12th). The Moon is in its crescent phase, so its light won’t diminish your ability to see the fainter meteors this year.

You don’t need any special equipment to enjoy the show, just some clear weather and preferably a viewing location away from city lights. From your backyard in an urban residential setting, you can expect to see a dozen meteors (“shooting stars”) every hour. But if you can get far from the glow of the city, you will be treated to more than one meteor per minute, some seen leaving behind a luminescent glow in their path and others ending their few seconds journey across the sky with a brief flash of light.

It’s best to use a full-body recliner when viewing the meteor shower, so you can comfortably stare straight up at the sky. You want your view to be filled with as much of the sky as possible, because the meteors can appear anywhere overhead, though they will seem to be coming from a point off towards the East (where the constellation Perseus is rising in the early part of the night).

Once you’ve set up your chairs and recliners and you and your companions are all settled in for viewing, turn off any outdoor lights, flashlights and your phones so you can let your eyes adapt to the darkness. It takes about 15 minutes for your eyes to fully adjust so you can see many more of the meteors. You will also see a lot more stars and the Milky Way too. Remember to bring some insect repellant, a blanket, some water and maybe some snacks and music to share with your friends while viewing.

Also, if you have binoculars, this is the perfect time to use them when you are ready to take a break from meteor watching. You don’t need star charts; just point your binoculars where you see brighter patches in the Milky Way to discover many of the famous nebulae and star clusters for yourself, just like Galileo and Messier first did hundreds of years ago.

Wishing everyone clear and darker skies!

–Dr. Ian Shelton, DDOD Chair

Observing Saturn and Jupiter in 2021

Saturn and Jupiter will be well placed for observing in the second half of the summer and into the Fall. DDOD Astronomers Dr. Ian Shelton and Dr. Tuba Koktay recently obtained images of the two planets using their 10-inch telescope from Richmond Hill in Ontario. The first image shows Jupiter with its Great Red Spot visible. The second image taken two hours later clearly shows how quickly the planet rotates. The third image displayed at the same scale as the first two images shows how Saturn’s much greater distance makes it look much smaller than Jupiter in telescopes, even though the two planets are actually similar in size.

On the night of August 1, 2021, Saturn will be at “Opposition”, meaning that it is as close to exactly opposite (180 degrees away from) the Sun as its orbit and our view of it from here on Earth allows. Observationally, Saturn will rise near sunset, set near sunrise, and be at its highest point in the sky as it passes due south (“transits”) at local midnight. As seen from Richmond Hill (and for much of the GTA), Saturn will rise at 20:35 EDT, sets at 6:14 EDT, and transits at 1:25 EDT.

Being at opposition also means that Earth is passing at its closest point to Saturn as the two planets travel along their respective orbits around the Sun. On this night, Saturn will be only 1.3367 billion kilometres away from us. Ok, not exactly what most people would consider “close”. But this is when Saturn appears largest in our telescopes, though still only about 18.6 arcsec in diameter (~100 times smaller than the full Moon). That’s for the ball of the planet; the rings extend about 1.3x further outward from the planet, spanning 43 arcsec. But the rings are never seen fully face-on and are currently tilted by about 18 degrees from being seen edge-on, making the rings look only ~13 arcsec wide. With an adequate telescope (at least a 75 mm lens or mirror, operating at 100x or more) and good atmospheric “seeing” (stability), this allows the southern hemisphere of the planet to now be partly visible again after having been blocked from view when the rings were near their maximum tilt of 27 degrees four years ago. We are currently seeing mostly Saturn’s northern hemisphere. But don’t expect to see any details on the ball of the planet: Saturn rarely shows anything but subtle bands wrapping around the planet.

On the night of August 19, 2021, it will be Jupiter’s turn to be at Opposition. Being 19% physically larger and orbiting at half the distance that Saturn orbits from the Sun, Jupiter will display a disk 49.1 arc-sec in equatorial diameter, more than double the apparent size of Saturn. And during Oppositions, Jupiter appears 25% larger than its average size as viewed from the Earth. The planet will be 600 million kilometres away from us on this night. Unlike Saturn, a modest size (~75mm) telescope is enough to reveal the bands and belts that perpetually define the upper layers of Jupiter. And even a good pair of binoculars will reveal Jupiter’s four largest moons, rearranging themselves into a different configuration each night as they orbit around the planet in just a few days. Three of these are larger than our own Moon.

Jupiter is easy to find in the night sky, looking brighter than any star. Saturn may prove a bit more challenging because it is 15 times fainter; but it is still about as bright as the top ten brightest stars in the sky, and so reveals itself by looking out of place if you know your constellations. The first sky map shown below will help you find the two planets this summer. It should match the sky if you are looking at around 11 pm in mid-August. If you are looking earlier in either the month or in the night, the planets and surrounding stars will appear further towards the East (E); if you are looking later in the night or the month, look for the planets further towards the West (W). The second sky map shows the region centred on Saturn at the time of its opposition (at 1:25 EDT on August 2).

To learn more about Saturn and Jupiter, have a look at the following websites:



Wishing everyone clear skies,

–Ian Shelton

Happy 86th Birthday DDO!


The David Dunlap Observatory’s official opening was on 31 May 1935, also Prof. Chant’s 70th birthday. The opening ceremony was attended by notables such as Sir Frank Dyson, and former Prime Minister William Lyon Mackenzie King, who praised the Observatory as “a gift to science all over the world.” Chant retired the same day and moved into Observatory House, the original pre-Confederationfarmhouse (built in 1864 for Alexander Marsh and known also as Elms Lea Alexander Marsh) just to the south of the administration buildings, where he spent his remaining years. In May 1939 the train carrying King George VI and Queen Elizabeth, the Queen Mother on their cross-Canada tour paused on the railway to view the Observatory and the largest telescope in the commonwealth. 

Presently, DDO has a rich heritage and offers public astronomy programs hosted by the City of Richmond Hill and provided by the program partners, DDODefenders and RASC.

To learn more please explore www.richmondhill.ca/Astronomy

-DDO Defenders : )

ISS passes Venus TONIGHT – and see Mercury too!

If you have a clear horizon, you can watch Venus setting about half an hour after sunset. And Tonight, the International Space Station (ISS) will appear to pass right above Venus at 9:36 EDT tonight. The ISS will be moving from left to right and will appear ~20x fainter than Venus. 

Note also that the much fainter “star” about 3 degrees above and a little to the left of Venus is actually the planet Mercury. Watch Venus move closer to it each night and then pass right beside Mercury on May 28.

-DDO Defenders

Great Ideas Speaker Nights: Searching for the First Stars at Cosmic Dawn

Great Ideas Speaker Nights with Dr. Omar López-Cruz on Saturday April 24th 2021 at 7:00pmEDT

Zoom link (Meeting ID: 850 1103 3763 Passcode: 653518)

We believe that the first stars in the universe formed about 200 million years after the Big Bang. Yet, we lack solid observational evidence about the timing of this epoch, called Cosmic Dawn.

The experiment SCI-HI is searching for the first stars at Cosmic Dawn by the detection of variations in the 21 cm Hydrogen line background as a function of cosmic time. Towards achieving our goal, we have sought radio quiet zones within Mexican Territory and have identified Isla Guadalupe in the Mexican Pacific Ocean 300 km off the Baja California Peninsula, as one of the best radio quiet zones in North America.

In this talk, Dr. López-Cruz will present the first SCI-HI results, some current improvements, and perspectives.


Dr. Omar López-Cruz is a Mexican Astronomer (M.Sc. & Ph.D.; Department of Astronomy, University of Toronto) who has worked on stellar classification and the evolution of galaxies in large density environments.

In 2014, he led an international team that proposed the cD galaxy Holm 15A as the host of the largest supermassive black hole (SMBH) in the local universe. In 2019, a German team led by Kianusch Mehrgan measured a mass of 40 billion times the mass of the Sun in Holm 15A, confirming the López-Cruz et al. conjecture. He also likes the popularization of Science. Recently he became the co-director of a book collection called La Biblioteca Científica del Ciudadano (The Citizen’s Scientific Library) aimed at encouraging the debate of scientific ideas in democratic societies. He appears on radio programs regularly and lectures widely on Astronomy and Scientific Affairs. He writes for magazines and newspapers in Mexico.

Zoom link (Meeting ID: 850 1103 3763 Passcode: 653518)

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 richmondhill.ca/astronomy 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 🙂