Astrophysics In Depth

Have you got some time on your hands? Tired of watching superficial youtube videos? Want some more depth in your knowledge of astronomy?

The Australian National University has 4 free on-line courses organized into a astrophysics xSeries that is offered on-line on the edX platform.

I have gone through two of the courses and can vouch for their high-quality. They have an awesome tag-team of instructors – one is a Nobel laureate and the other an award winning professor and educator. These are superbly crafted courses, filled with interesting details on the techniques, research, knowledge and remaining mysteries of astrophysics. Both instructors are highly qualified, to say the least, and obviously enjoy their work. They have a knack for clear communication and plain speaking and make complex topics understandable. Anyone taking these courses will not just learn a lot about astrophysics, but also about the thought process used by astrophysicists in tackling the mysteries of the universe. 

The courses in the series are:

Astrophysics: The Violent Universe
Image Credit: NASA Hubble

Greatest Unsolved Mysteries of the Universe: This course will take you through nine of the greatest unsolved problems of modern astrophysics. We don’t know why the Big Bang happened. We don’t know what most of the universe is made of. We don’t know whether there is life in space. We don’t know how planets form, how black holes get so big, or where the first stars have gone. Learn what we do know and don’t know, and get an up-to-date understanding of current research

Image Credit: Credit: NASA/JPL-Caltech/R. Hurt, T. Pyle (IPAC)

Exploring Exoplanets: Explore the mysteries of exoplanets – planets around other stars. The discovery of exoplanets is one of the greatest revolutions in modern astrophysics, with the finding that the universe is teeming with planets. They are a strange bunch, from hot Jupiter-like planets skimming the surfaces of their stars to cold and lonely free-floating planets far from any star, and even planets orbiting neutron stars. This course will bring you up-to-date with the latest research on exoplanets, and how it has revolutionized our understanding of the formation of solar systems like our own.

Image Credit: NASA GFRC Dana Berry

The Violent Universe: Covers the deadliest and most mysterious parts of our universe, such as black holes that warp the fabric of space and time; or white-dwarf stars and neutron stars, where the laws of quantum mechanics collide with relativity. The course also covers dwarf novae, classical novae, supernovae and even hypernovae: the most violent explosions in the cosmos.

Galaxy superclusters in the nearby universe. Image credit: Richard Powell CC-BY-SA-2.5

Cosmology: the study of the nature of the entire universe, its origin, and its ultimate fate. Where did it come from? How will it end? What is the nature of space and time? Learn how recent advances give precise, reliable answers to many cosmological questions but still leave many of the most fundamental mysteries unsolved.

This might be your only chance to take a course from a Nobel Prize winner! One of the instructors, Brian Schmidt, shared the 2011 Nobel Prize in Physics with Saul Perlmutter and Adam Riess for providing evidence that the expansion of the universe is accelerating.

The other instructor is Paul Francis, an ANU professor and distinguished educator. He was awarded the 2016 Australian Award for University Teaching and Award for Teaching Excellence. Notable guest speakers, such as Lawrence Krauss and Brian Cox, make appearances to help you explore the theories behind modern cosmology and astrophysics.

Verified certificate available for a small fee.

These courses are designed for people who would like to get a deeper understanding of these mysteries than that offered by popular science articles and shows – one course can take 8 to 9 weeks if you devote 3-5 hours per week to it. Anyone can take the courses for free – you get the sheer joy of learning and can even skip out on the quizzes and assignments. Or you can pay a small fee and earn a certificate provided you get a mark of 70% or higher.

The courses are self-paced so they can match your schedule. Each is delivered as a set of videos with short quizzes between the videos to test your understanding. There are handout notes, a discussion forum, homework assignments and a final exam – just like an in-person college class. A cool on-going mystery project helps you experience what it is like to be a research astrophysicist. The project gives out clues, data, and discoveries about a made-up universe, very different from our own, after each section. These are discussed and you are challenged with developing an understanding and theories about this new universe.

You will get the most out of these courses if you have done math and physics in high-school and are willing to put that knowledge to work. Most of the math is “back-of-the-envelope” calculations that can be done on a note pad. But you can still learn a lot by skipping the math and just watching the videos.

Unwind under a Clear Dark Sky Tonight

Clear skies are in the forecast for tonight. Take some inspiration from a message, sent out by the International Dark Sky Association, to get out and unwind under a dark sky.

Photo credit @Alivia Dey — at West End, Vancouver.

Many of us are facing new anxiety and fear due to the uncertainty and enormity of what we are experiencing together. Studies have demonstrated how just ten minutes in nature brings benefits to our health and wellbeing. Dark Sky supporters often share stories about the rejuvenation they feel under the stars. Taking a few moments to look up at the sky at the end of the day – whether from a window, balcony, back yard, or park – can help lift the spirits and remind us that we are all connected under one big sky.”

Ruskin Hartley, International Dark-Sky Association

You might like to start early by applauding our health care workers at 7 pm then wait for the skies to have darkened by 9pm. Try turning off any unnecessary lighting to help reduce light pollution and help everyone get a better view of the celestial wonders.

Venus will be brilliant in the West.  Orion and the Orion Nebula (if you have binoculars) will be in the south-west. The brightest star in the sky, Sirius, is a little more to the south.  If you have a telescope then comet ATLAS is in the North and getting really bright fast – check out Tim Yaworski’s youtube video about this comet. Tim is a RASC Saskatoon member.

https://youtu.be/I3ikdcN7yME

Nova Newsletter – Mar/Apr 2020

Our NOVA Newsletter for Mar-Apr 2020 is available as a pdf file. An archive of older issues can be found on our Newsletter page.

Contents of Volume 2020, Issue 2, Mar-Apr 2020:

  • General Assembly Vancouver 2020 Update by Hayley Miller
  • International Women’s Day Girl Guide Event by Hayley Miller
  • President’s Message by Gordon Farrell
  • Can We See the Whole Universe by Andrew Krysa
  • My First LPA (Light Pollution Abatement) Report by Leigh Cummings
  • Are the Weather Gods Mad at Us? by J. Karl Miller

Hogg and Seager at RASC 2020 GA

RASC General Assembly June 5 to 7 2020 Executive Plaza Hotel Coquiltam BC

Two Canadian women astronomers are featured prominently at the Hogg Memorial Lecture that is part of the RASC 2020 General Assembly in Vancouver. The Hogg Lecture is named in recognition of the lifelong contributions of Dr. Helen Sawyer Hogg towards increasing public awareness and appreciation of the Universe. It is held annually alternating between the RASC General Assembly in even-numbered years and CASCA’s conference in odd-numbered years. Dr. Sara Seager is delivering this year’s Hogg Lecture during the RASC 2020 GA on June 6th, 7:00 pm at Simon Fraser University. The lecture is free and open to the public – register now.

Dr. Helen Sawyer Hogg

Dr. Hogg was a notable woman of science in a time when many universities would not grant scientific degrees to women. As an astronomer, she is recognized for pioneering research into globular clusters and variable stars.

Helen Sawyer Hogg at Telescope
Helen Sawyer Hogg. beside her beloved David Dunlap 74-inch telescope in Toronto

Hogg did graduate work at the Harvard Observatory where she worked with Dr. Harlow Shapley measuring the size and brightness of globular clusters and publishing several papers. Hogg received her master’s and doctoral degrees from Radcliffe College because, at that time, Harvard refused to award graduate degrees in science to women.

In 1931, she and her husband Frank set out in their Model A Ford for Victoria BC and the Dominion Astrophysical Observatory where a position awaited Frank. There was no opening at the DAO for Helen, but the Director gave her the use of the 72-inch telescope to further her research. The couple moved to Toronto’s “new” Dunlop Observatory in 1935 where Hogg continued her study of variable stars in globular clusters.

Her successful professional career was matched by her generous community activities, many of them reflecting her efforts to ensure that

“The Stars Belong to Everyone”

Helen Sawyer Hogg

which is the title of one of her popular books and adopted as the theme of the 2020 GA. She prepared a weekly astronomy column for The Toronto Star for 30 years, starred in an astronomy TV show, and wrote numerous articles for the Journal of the RASC. She was the first woman president of the physical sciences section of the Royal Society of Canada, as well as the first female president of the Royal Canadian Institute, and a national RASC president.

Helen Sawyer Hogg Plaque
Canada Museum of Science and Technology, plaque to Dr. Helen Sawyer Hogg.

Dr. Hogg was promoted to a Companion of the Order of Canada in 1976 and posthumously inducted into the Canadian Science and Engineering Hall of Fame. RASC included her among 15 eminent astronomers that were named as Honorary RASC Members.

Dr. Sara Seager

The Hogg lecture at the 2020 General Assembly will be given by Dr. Sara Seager. She is a planetary scientist and astrophysicist at the Massachusetts Institute of Technology. Dr. Seager has pioneered research in the field of exoplanet atmospheres and now, like an astronomical Indiana Jones, is on a quest seeking the field’s holy grail, another Earth-like planet, searching for life by way of exoplanet atmospheric biosignature gases.

Seager’s research has introduced many new ideas to the field of exoplanet characterization, including work that led to the first detection of an exoplanet atmosphere. She was part of a team that co-discovered the first detection of light emitted from an exoplanet and the first spectrum of an exoplanet.

The light blue region depicts the “conventional” habitable zone for planets
Image credit: Sara Seager, Science 03 May 2013: Vol. 340, Issue 6132

Seager’s research now focuses on theoretical models of atmospheres and interiors of all kinds of exoplanets as well as novel space science missions.

Her Hogg lecture on Mapping the Nearest Stars for Habitable Worlds is free and open to the public.

She is the author of two textbooks and has been recognized for her research by Popular Science, Discover Magazine, Nature, and TIME Magazine. Seager was awarded a MacArthur Fellowship in 2013.

Professor Sara Seager was born and grew up in Toronto, Canada. Among her first memories is a trip to a “star party” with her father, to see the moon through a telescope—spectacular! Professor Seager graduated from Jarvis Collegiate Institute, a 200-year old public high school known for its science education. During high school she was astounded to learn that one could be an astrophysicist for a living, only to be deterred by her father, who believed the best career was as a doctor or lawyer.

Seager graduated with a BSc in the Math and Physics Specialist Program at the University of Toronto. Like Hogg, she did graduate work at Harvard where her realization of the surprising diversity of exoplanets has led to Seager’s maxim, “For exoplanets, anything is possible under the laws of physics and chemistry.”

Enjoy the Leap Day While You Can

Today, February 29th 2020, is a leap day with an extra 24 hours added to the calendar. The extra day is added to keep our calendar aligned with the seasons. The need for a Leap Day is a result of the physics with the Earth rotating on its axis while simultaneously revolving around the Sun. Physics also explains why the need for leap years will eventually disappear!

Image Credit: timeanddate.com

Our calendar year is designed to match the seasons, which occur because of the axial tilt of the Earth. At the June solstice, the northern hemisphere is tilted towards the sun but it is tilted away from the Sun at the December solstice. Neither hemisphere is tilted towards or away from the Sun at the equinoxes.

Solar Day vs Sidereal Day
The Solar Day vs Sidereal Day
Image credit: www.solarsystemscope.com/

But the Earth is also simultaneously spinning on its own axis, with a period of 24 hours that make up our cycle of days and nights. The 24-hour solar day is the time it takes between successive “noons” – the time when the Sun reaches its highest point in the sky as seen from Earth. The solar day is about 4 minutes longer than the time the Earth to rotate by 360 degrees (called the sidereal day) because the Earth is moving around Sun during each day.

The calendar was originally intended to start at the Spring Equinox with a calendar year measuring the time it takes for the Earth to revolve around the Sun and make it to the next Spring Equinox.

The calendar year is the period of our orbit around the Sun but it does not match up with the whole number of 365 solar days – it takes a bit of an extra day for the Earth to get back to the same position with respect to the Sun.

The calendar year is 365.24219 solar days.

Image Credit: www.ctvnews.ca

The extra 0.24219 days is close to 0.25 or ¼ of a day so adding an extra day every 4 years keeps the seasons and the calendar synchronized. It is a bit more complicated because the extra 0.24219 is not exactly ¼ and the Gregorian Calendar accounts for this with its leap year rule:

A year is a leap year if it is evenly divisible by four,
but years that are divisible by 100 are not leap years,
unless they are also divisible by 400.

For example, 2020 is a leap year, the years 1700, 1800, and 1900 are not leap years, but the years 1600 and 2000 are.

In the long term, changes in the Earth’s rotation rate need to be taken into account. The Earth’s rotation rate is slowing down, mostly due to the tidal forces and friction between the Earth and Moon. The day gets about 1.4 milliseconds, or 1.4 thousandths of a second, longer roughly every 100 years. A leap second is occasionally applied to accommodate for this slowdown in the Earth’s rotation and other irregularities. If you can wait around for about another four million years then the day will have lengthen by about 56 seconds. That is enough so that a calendar year will have exactly 365 solar days and we won’t need a leap year!

So enjoy the leap day while you can and a Happy Birthday any leaplings born on Feb 29th.

Betelgeuse is BIG (and variable)

Betelgeuse is a bright star in the shoulder or armpit of the constellation Orion. It is easily visible in February and March from Vancouver around 10 pm, close to the southern Horizon.

Betelgeuse in Orion
Betelgeuse in the constellation Orion. Near the Southern Horizon from Coquitlam on Feb 18th, 2020

If you follow astronomy news at all you’ll have heard that Betelgeuse has recently been dimming. Betelgeuse is a variable star whose brightness is known to periodically rise and fall, but it’s recent dimming has been quite extraordinary. Especially exciting is speculation that Betelgeuse may explode as a brilliant supernova which would be visible even in daylight. Unfortunately the latest measurements have shown that Betelgeuse may be brightening again,

Less often reported is that Betelgeuse is BIG! – not too surprising given that it is classified as a red supergiant. So how big is it?

  • It is so big that its diameter is about 1300 times that of our sun.
  • It is so big that if placed at our Sun’s location, the outer edge of its photosphere would reach out to Jupiter.
  • It is so big that it was the first star to have its angular diameter measured. Stars are so far away that they appear as pinpoints of light whose angular diameter cannot be determined. But Betelgeuse was big enough that 100 years ago, in 1920, it was the prime candidate to submit to measurement of its angular diameter.
Betelgeuse Sun Size Comparison
Size Comparison of Betelgeuse and our Sun
Betelgeuse Overlay on Solar System
Betelgeuse overlaid on the Solar System
Image credit: ALMA (ESO/NAOJ/NRAO)/E. O’Gorman/P. Kervella

Michelson and Pease used the 2.5 m Hooker telescope at the Mount Wilson Observatory in California – the largest telescope in the world between 1917 and 1949 – but even it was not large enough to resolve the disk of Betelgeuse. Instead Michelson turned the telescope into an interferometer by attaching a framework with 4 six inch mirrors to the front of the telescope.

Michelson interferometer for measuring star diameters, attached to front of the 2.5m Hooker telescope.

The mirrors created 4 separate light paths of the star that combined, due to the wave nature of light, into an interference pattern.

Astronomical interferometers can produce higher resolution astronomical images than any other type of telescope – theoretically producing images with the angular resolution of a huge telescope with an aperture equal to the separation between the light paths. The separation between the mirrors of Michelson and Pease’s interferometer at Mount Wilson was about 20 feet (or 6 m) and this proved sufficient for them to measure the angular diameter of Betelgeuse as 0.047 arc-seconds.

Once you know the angular diameter, then if you also know the distance of the star, you can easily get its linear diameter in space. Michelson and Pease used several estimates of the distance to Betelgeuse available in 1920 to come up with a linear diameter of 386,000,000 km, somewhat smaller than more modern estimates. Using their 0.047 arc-seconds angular diameter with current estimates of the distance to Betelgeuse (about 724 light years) gives a linear diameter of 1.83 billion km — a truly colossal diameter, the equivalent of over 1,300 solar diameters!

Michelson and Pease published their results in the May 1921 edition of the Astrophysical Journal but a summary “Betelgeuse: How its Diameter was measured” appeared one month earlier in the April 1921 edition of the RASC Journal.

Betelgeuse is a peculiar star that is subjected to pulsation cycles that not only make is brightness vary but also make its size vary. Long-term monitoring by UC Berkeley’s Infrared Spatial Interferometer (ISI) on the top of Mt. Wilson show that Betelgeuse shrunk in diameter by more than 15% from 1993 to 2009. Recent images show that Betelgeuse has an asymmetric surface and appears to be shedding gas and dust at tremendous rates.

Asymmetric surface of Betelgeuse in Jan 2019
Astronomers used ESO’s Very Large Telescope to discovered a plume of gas ejected from Betelgeuse and a gigantic bubble that boils away on its surface. 
Image Credit: ALMA (ESO/NAOJ/NRAO)/E. O’Gorman/P. Kervella

Since Betelgeuse has a radius 1,300 times that of the Sun, it has a volume about 1.3 billion times larger than the Sun. But its mass is only about 8 – 20 times the Sun. This means the density of Betelgeuse is much, much lower than the Sun. The average density of the Sun is about 1.4 grams/cc – somewhat higher than the density of water. In contrast, the average density of Betelgeuse is just 12 billionths of a gram/cc. This is about a million times less dense than Earth’s atmosphere at sea level, or about the same as a vacuum found in an insulating Thermos bottle.

Celebrate 40+ Years of the Canada-France-Hawaii Telescope

Canada-France-Hawaii Telesocpe located atop the summit of Mauna Kea, Hawaii

Come celebrate 40+ years of operations at the Canada-France-Hawaii Telescope (CFHT) at our Paul Sykes Memorial Lecture. 2019 marked the 40th anniversary of the Canada-France-Hawaii Telescope. Hear stories of the science, staff, and their adventures over those 40 years along with plans for the future.

Speaker: Mary Beth Laychak, CFHT Director of Strategic Communications
Title: 40 Years of Astronomy at the Top of the World

When: Friday, February 21, 2020 from 7:30 PM to 9:30 PM
Where: Saywell Hall, Room SWH10081, SFU Burnaby Campus

The event is free and open to the public! Our meetup event has additional details, directions, and a map.

Framed CFHT posters will be available for sale as special merchandise. The posters are from Dynamic Structures, a BC company located in Port Coquitlam, who did important engineering work in constructing the CFH telescope and enclosure – find out more at the RASC 2020 General Assembly in June where David Halliday, president of Dynamic Structures, is one the speakers.

Mary Beth Laychak, Director of Strategic Communications at the CFHT.
Mary Beth Laychak is the Director of Strategic Communications at the CFHT

Mary Beth has an undergraduate degree in astronomy and astrophysics from Penn State University and a masters degree in educational technology from San Diego State. Her passions include astronomy, sharing astronomy with the public, astronomy based crafts, and running.

The Canada-France-Hawaii Telescope is a joint facility of the National Research Council of Canada, the Centre National de la Recherche Scientifique of France, and the University of Hawaii. The 3.6m telescope is located on the summit ridge of Mauna Kea, a 4200 meter, dormant volcano on the Big Island of Hawaii.

Inside the CFHT Observatory Enclosure. Image credit: National Research Council of Canada

CFHT crucially supported seminal observations:

  • The discovery of Dark Energy,
  • The first detections of cosmic gravitational lenses that paved the way to mapping dark matter across the universe, and
  • Tracking the first interstellar asteroid (Oumuamua) as it sped through our solar system

The CFHT remains at the forefront of astronomy thanks to the quality of its site, its state-of-the-art instrumentation, and the dedication of its staff. CFHT’s annual publications rate now exceeds 200 papers per year and has never been higher. The same can be said for CFHT’s #2 worldwide ranking for overall “science impact” in astronomy


The Annual Paul Skyes Memorial Lectures

These lectures honour Paul Sykes. Paul actively pursued his interest in astronomy, attending conferences and joining RASC, where he became a Life Member. Paul Sykes passed away in October 2005 at the age of 87 and left the Vancouver Centre a generous gift.

Paul Sykes was born in Hummelston, Pennsylvania USA in 1918. He acquired his interest in astronomy at an early age. During his teens he published his own monthly astronomical column and gave at least one lecture.

He was an officer in the United States Air Force, served in the Pacific during WWII attaining the rank of Captain. He was awarded a Presidential Unit Citation, the U.S. Air Medal, the Oak Leaf and Cluster and the Bronze Star. Following the war he attended UBC earning a degree in Physics in 1948. He rejoined the United States Air Force and attended the Oak Ridge School of Reactor Technology, studying nuclear physics. He worked on the NERVA Project, a nuclear rocket development effort and rose to the rank of Major.

Paul was appointed a lecturer and administrator in Physics at UBC and remained there until retirement in 1983.

Two Women’s Contributions to Measuring Distances

Today is an appropriate day to celebrate the significant discoveries of Henrietta Swan Leavitt and Sandra Faber in measuring distances in the Universe as Feb 11th is recognized by the United Nations as its International Day of Women and Girls in Science.

Many amateur astronomers know of the significance of Henrietta Swan Leavitt’s discovery of the period-luminosity relationship in Cepheid Variable stars; the longer the period of a Cepheid, the more luminous it is. Edwin Hubble used this relationship with his observations of Cepheid Variable stars in the Andromeda Galaxy (M31) to estimate that the Andromeda Galaxy lies at a distance of 1.5 million light-years; thus resolving the Great Debate with Harlow Shapley conceding that spiral “nebulae” (what we now call galaxies) are located outside our milky way.

Plot prepared by Leavitt in 1912. Period on the x-axis and brightness on the y- axis for 25 Cepheids in the Small Magellanic Cloud (SMC). The relation also holds for luminosity because all stars in the SMC are at about the same distance from Earth.


The luminosity of a star is the total amount of light it emits from its surface. On the other hand, how bright a star appears depends on its luminosity and its distance from the observer because the light spreads out over a greater surface area, in accordance with the inverse square law.


Leavitt’s work was critical because once the luminosity is known, the brightness  from Earth can be measured and the distance estimated from the inverse square law.

Image Credit: Australian Telescope National Facility – CSIRO

Later in the 1970s, Sandra Faber found another luminosity relationship. Faber was following up on some of her thesis work that looked at absorption lines — those of calcium, sodium, or magnesium in the visible portion of a galaxy’s spectrum — when she spotted some evidence this relationship.

“Well, as I was taking the data, I could not help but notice that the more luminous galaxies had broader lines.” 

Sandra Faber interview in 2019

Further data analysis revealed a pretty good empirical relation between the luminosity and the velocity dispersion of stars near the centre of elliptical galaxies. This relationship became known as the Faber-Jackson relation after the work was published in a paper authored by Faber and Robert Jackson, her research assistant at the time. For any visible elliptical galaxy, the velocity dispersion can be measured from the width of the absorption lines and its luminosity estimated using the Faber-Jackson relation. The distance to the galaxy can then be calculated using the inverse-square law applied to its luminosity and its observed brightness from Earth.

Velocity dispersion (y-axis) plotted against absolute magnitude (x-axis) for a sample of elliptical galaxies, with the Faber–Jackson relation shown in blue. Image Credit: Wikipedia

Faber refined these methods as the head of a group, known as the Seven Samurai, on a project to measure distances and velocities of a sample of elliptical galaxies. The project failed to validate its original hypotheses on more accurate versions of the Faber-Jackson relationship but it did establish distances to 400 galaxies. Using these distances, they made a map of ellipticals around us and noticed that the recessional speeds were not exactly as predicted from a simple uniform Hubble law (due to the expansion of the Universe). Faber recalled, David Burnstein, one of he seven samurai remarking

“Look at this. There’s a whole region in Centaurus, and it’s moving at 1000 kilometres a second”

Dave Burstein remark, recollection by Faber in 2019,

Instead, large patches of the Universe were moving away from us too quickly or too slowly! This work culminated at a small meeting of cosmological experts in Hawaii in January 1986. The samurai sliced up the standard theories of the time, by announcing that the universe was expanding lopsidedly. A vast region of space 500 million light-years in diameter, containing hundreds of thousands of galaxies, was being drawn toward a huge concentration of mass later dubbed the Great Attractor. One attendee at the meeting said “In 20 years of science reporting, I have never seen such pandemonium at a scientific meeting”.

Faber has done significant research in other areas and has been recognized with numerous awards. Earlier this year in Jan 2020, the Royal Astronomical Society awarded her its Gold Medal in Astronomy. The award recognizes Faber “for her outstanding research on the formation, structure and evolution of galaxies, and for her contributions to the optical design of the Keck Telescopes and other novel astronomical instruments.”