Canadian Astronomical Society
2025 Helen Swayer Hogg Public Lecture: JJ Kavelaars
How did our solar system come together, and what can its smallest members tell us about how planets are born? In this talk, we’ll explore the remarkable clues hidden in asteroids, Kuiper Belt objects, and even rare interstellar visitors—ancient remnants from the dawn of planetary formation. These rocky and icy bodies preserve a record of the early processes that shaped the planets, including Earth. We’ll look at how discoveries from space missions and telescopic surveys have transformed our understanding, and how the upcoming Vera C. Rubin Observatory and its Legacy Survey of Space and Time (LSST) will revolutionize the search for these cosmic fossils. With LSST, we expect to uncover hundreds of thousands of new small bodies—and perhaps even more interstellar visitors—opening an unprecedented window into the origins of planetary systems.
2023 Helen Swayer Hogg Public Lecture: Kristine Spekkens
Understanding how galaxies form and evolve within the standard cosmological framework that describes the Universe is among the biggest challenges in astronomy today. The properties of gas-rich, star-forming nearby galaxies are key to this picture, both because they resemble the Milky Way in which we live and because they make up the bulk of the galaxy population in most cosmic environments. This talk will describe the connection between galaxies, dark matter and cosmology, how the atomic gas in galaxies is a powerful cosmological probe, and how a revolution in our view of these objects and many others the night sky is underway with a new generation of radio telescopes. These facilities are paving the way for ground-breaking discoveries with the SKA telescope – an international mega-science project in which Canada will soon be a full member – which will come online towards the end of this decade.
2021 Helen Swayer Hogg Public Lecture: Andrea Ghez
Learn about new developments in the study of supermassive black holes. Through the capture and analysis of twenty years of high-resolution imaging, the UCLA Galactic Center Group has moved the case for a supermassive black hole at the center of our galaxy from a possibility to a certainty and provided the best evidence to date for the existence of these truly exotic objects. This was made possible with the first measurements of stellar orbits around a galactic nucleus. Further advances in state-of-the-art of high-resolution imaging technology on the world’s largest telescopes have greatly expanded the power of using stellar orbits to study black holes. Recent observations have revealed an environment around the black hole that is quite unexpected (young stars where there should be none; a lack of old stars where there should be many; and a puzzling new class of objects). Continued measurements of the motions of stars have solved many of the puzzles posed by these perplexing populations of stars. This work is providing insight into how black holes grow and the role that they play in regulating the growth of their host galaxies. Measurements this past year of stellar orbits at the Galactic Center have provided new insight on how gravity works near a supermassive hole, a new and unexplored regime for this fundamental force of nature.
2019 Helen Swayer Hogg Public Lecture: Sera Markoff
Black holes are one of the most exotic consequences of Einstein’s General Relativity, yet they are also very common, from stellar remnants up to beasts over a billion times more massive than our sun. Contrary to their reputation as cosmic vacuum cleaners, they actually serve as engines for extremely energetic processes, converting a large fraction of the ‘fuel’ they capture into other forms that can majorly impact their surroundings. For instance, some black holes launch enormous jets of relativistic plasma, bigger than their host galaxies, that accelerate particles to energies millions of times higher than the Large Hadron Collider at CERN! Astronomers, astrophysicists and physicists all want to understand black holes, yet we have been limited by the resolution of our telescopes from actually seeing one directly. This situation has changed dramatically with the Event Horizon Telescope, an Earth-sized millimeter-wavelength array that revealed to the world what a black hole actually looks like just this past April. I will put this exciting result into context by explaining more about how black holes become such efficient, gravity-powered engines, and why they are important players for many different fields of study. Along the way I will also discuss the areas where we still have major questions, and thus the challenges for the coming years.
2018 Helen Swayer Hogg Public Lecture: Emily Lakdawalla
In the last two decades, dozens of spacecraft have explored planets, moons, asteroids, and comets, returning a treasure trove of scientific data. Thanks to generous data release policies and the proliferation of high-speed Internet, the worldwide public has rapid access to huge quantities of spacecraft image data. Skilled amateur image processors produce stunning views of alien places, and represent a valuable and underutilized resource for increasing public support of planetary exploration. I'll present some of the beautiful work being done by these amateurs and discuss ways that they can benefit planetary science.
2017 Helen Swayer Hogg Public Lecture: Fiona Harrison
Fiona's interest in observational high energy astronomy led her to become the Principal Investigator of NASA's NuSTAR Explorer mission, the first orbiting X-ray telescope with the ability to focus high energy X-rays. Since its launch in 2012, NuSTAR has uncovered a number of important scientific results, including the identification of a number of “hidden” close-by supermassive black holes, the discovery of the brightest X-ray pulsar ever recorded and the creation of the first map of radioactive material in a supernova. These, plus many other discoveries, have greatly enhanced our view of the X-ray Universe in just four years.
2016 Helen Swayer Hogg Public Lecture: Ann Hornschemeier
Excitement has mounted recently over the role of X-ray emission from galaxies in early heating of the Intergalactic Medium (IGM), demonstrating that understanding of X-ray emission from normal and starburst galaxies may have significant impact on structure formation in the Universe. Here we present our research on constraining the X-ray SED of galaxies across cosmic time via several complementary approaches.
In the very local universe (d <~ 30 Mpc including the Local Group) we are using NuSTAR to understand the accretion states and total output of black hole and neutron star binaries using the important lever arm of 0.5-30 keV emission. At intermediate distances (10-100 Mpc), we are comparing the X-ray output of galaxies with star formation histories and population synthesis model predictions using both Chandra and XMM data.
In the slightly more distant universe (z~0.1-0.2) we can find rare analogs to primordial starbursts via wide-field optical/UV surveys that may be studied with Chandra.
We will finish with a discussion of starburst galaxies emitting X-rays at z>4, which thanks to the extremely deep Chandra Deep Field-South 7 Ms survey, are better constrained than ever before. I will discuss survey strategy and how the various pieces of the puzzle fit together regarding the X-ray output of galaxies and their X-ray binary populations over cosmic time.
2015 Helen Swayer Hogg Public Lecture: Roberto Abraham
Bigger telescopes are usually better telescopes…but not always. In this talk Dr. Abraham will explore the ghostly world of large low surface brightness structures, such as galactic stellar halos, low-surface brightness dwarf galaxies, and other exotica such as supernova light echoes. These objects are nearly undetectable with conventional telescopes, but their properties may hold the key to understanding how galaxies assemble. He will describe why finding these objects is important, and why it is so devilishly difficult. He will also describe a bizarre new telescope (the Toronto/Yale Dragonfly Telephoto Array, a.k.a. Dragonfly) which is now being used to explore the low surface brightness universe and is testing some of the most fundamental predictions of galaxy formation models. Dragonfly is comprised of multiple commercial 400 mm f/2.8 telephoto lenses which utilize novel nanostructure-based optical coatings that minimize scattered light and ghosting. He’ll showcase some early results, mainly focusing on the properties of ultra-faint stellar halos. He’ll also report the discovery of gigantic stellar disks underlying nearby galaxies, and will describe the discovery of a new class of ghostlike galaxies that are as big as the Milky Way but have about 1/1000 of its mass.
2014 Helen Swayer Hogg Public Lecture: Laura Ferrarese
When peering into the cosmos, astronomers can only gather instantaneous snapshots of celestial objects whose evolution — with rare exceptions — unfolds on timescales far too long to be probed within a human lifetime. To complicate things further, what our instruments can actually “see” adds up to less than 5% of the matter/energy content of the Universe. Take galaxies, for instance: with their evolution controlled by black holes and dark matter, neither of which our instruments can probe directly, there is much more than meets the eye! This lecture will focus on how galaxies are transformed throughout cosmic times, how they interact with each other and with the environment in which they live, and how the 5% we can see can tell us about the 95% we cannot see.
2013 Helen Swayer Hogg Public Lecture: Malcolm Longair
The lecture will describe the remarkable history of our understanding of the origin and evolution of our Universe from the time of Newton to the present day. The story culminates with the announcement of the first results of the ESA Planck mission, which has provided the clearest image of the early Universe yet produced and a wealth of new results of cosmological importance. The results will be placed in the context of the historical development of the subject. The next great cosmological challenges will also be addressed. The lecture will be delivered at a non-technical level and will be profusely illustrated by the most recent images, simulations and videos.
2012 Helen Swayer Hogg Public Lecture: Dame Jocelyn Bell Burnell
The Mayan Calendar ends in December 2012 and according to some a nearby supernova explosion could extinguish all life on earth then. Is there astronomical evidence for this defeatism?
A long count in the ancient Mayan Calendar ends in December 2012. According to some this means the world will come to an end then. How will this happen? Some suggest a collision with an undiscovered planet or with a large amount of comets could destroy the planet. Others speculate that a nearby supernova explosion could extinguish all life on earth, or that the Sun might enter the galactic disc and that this results in mass extinction. Jocelyn Bell Burnell will look at astronomical phenomena that might cause the end of the world and she will examine how true or likely they are. Will we have our last New Year?
2011 Helen Swayer Hogg Public Lecture: Dimitar Sasselov
Dimitar Sasselov will highlight efforts to discover potentially habitable Earth-size planets. As a co-investigator of NASA’s Kepler mission, Sasselov searches for extra-solar planets by viewing the dimming of starlight, as a planet crosses the face of its star. This simple and elegant method has led to a bounty of newly-discovered planets and allowed exploration of their properties and atmospheric chemistry.
2010 Helen Swayer Hogg Public Lecture: René Doyon
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2009 Helen Swayer Hogg Public Lecture: Lawrence Krauss
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2008 Helen Swayer Hogg Public Lecture: Phil Plait
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2007 Helen Swayer Hogg Public Lecture: Steven Squyres
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2006 Helen Swayer Hogg Public Lecture: Alan Hildebrand
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2005 Helen Swayer Hogg Public Lecture: Michel Mayor
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2004 Helen Swayer Hogg Public Lecture: Sara Schechner
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2003 Helen Swayer Hogg Public Lecture: Michael Shara
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2002 Helen Swayer Hogg Public Lecture: Paul Hodge
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2001 Helen Swayer Hogg Public Lecture: Jill Tarter
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2000 Helen Swayer Hogg Public Lecture: Wendy Freedman
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1999 Helen Swayer Hogg Public Lecture: Paul Chodas
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1998 Helen Swayer Hogg Public Lecture: David Crampton
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1997 Helen Swayer Hogg Public Lecture: Vera Rubin
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1996 Helen Swayer Hogg Public Lecture: Werner Israel
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1995 Helen Swayer Hogg Public Lecture: David H. Levy
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1994 Helen Swayer Hogg Public Lecture: George Efstathiou
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1993 Helen Swayer Hogg Public Lecture: Margaret Geller
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1992 Helen Swayer Hogg Public Lecture: Alan R. Hildebrand
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1991 Helen Swayer Hogg Public Lecture: Kimmo A. Innanen
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1990 Helen Swayer Hogg Public Lecture: Joseph Veverka
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1989 Helen Swayer Hogg Public Lecture: Roger Cayrel
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1988 Helen Swayer Hogg Public Lecture: Hubert Reeves
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1987 Helen Swayer Hogg Public Lecture: René Racine
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1986 Helen Swayer Hogg Public Lecture: Barry Madore
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1985 Helen Swayer Hogg Public Lecture: Owen Gingerich
Abstract not available.