Rainbows and Their Cousins

Here at PVL we do love atmospheric optical phenomena! I can report that, more than once, we were headed somewhere as a group and got delayed by particularly impressive parahelia, arcs or other interesting effects. While they often go unnoticed, such effects are more common than you might imagine. Robert Greenler, author of the lab-favourite "Rainbows, Halos and Glories" estimates that you can see at least one of the effects Alex describes below on about one day in three. So the next time you are outside: look up, fair reader, and take a glance a few tens of degrees from the sun! You might be surprised and impressed with what you find.

By Alex Innanen

It’s pride month, which means everything is decked out in rainbows from street corners to store shelves, and also I’ve been thinking about rainbows all month. So for your education and enjoyment some pictures of rainbows and other pretty atmospheric optics, and some of the science behind them.

 
A quick overview about the visible light spectrum: We all know that white light is made up of the colours of the visible spectrum which spans from red to violet. When Newton performed his experiments with prisms he identified seven colours – the classic ROYGBIV – but in truth the spectrum is continuous, and in fact those whose languages have fewer colour terms will actually perceive the divisions between colours differently (this is really really cool and unfortunately outside the scope of this post, and also I’m not a psychologist but there’s a nifty paper on it). IF you’ve ever listened to Pink Floyd or possibly performed an elementary school science experiment, you know that passing white light through a prism splits it up into the rainbow. This is because light refracts, or bends, when it goes from one medium to another such as air to glass. When light encounters the glass of a prism it moves slower, and the angle that it refracts is based on both the index of refraction of the material and the specific wavelength. Red has the greatest wavelength and is refracted at a smaller angle than blue. If the differences in angles of refraction are large enough, the different colours will ‘spread out’, or disperse.

Deciding to Start a Family While Being a STEM Graduate Student

A few weeks ago, PhD Candidate Charissa Campbell began a leave from the lab. From all of us at the PVL - we wish her well in her time away and look forward to her return next year!

by Charissa Campbell

Being a woman in STEM can come with certain challenges, including deciding if you want to start your family or not. Since women have to carry and be the primary caregiver for the first year it can be a difficult decision whether to put off starting that next step in your life. Luckily, there are a lot more benefits available to women who want to start their family while also being a graduate student. Knowing this, my partner and I decided to make the decision to start our own family after getting the surprise that I was expecting.

To find Life on Mars, we need to do some real digging

 

This week PVL MSc candidate, Hemani Kalucha interviews a professor from her undergraduate institution about a few of the factors affecting our search for life on Mars. Image above from: https://geosciences.princeton.edu/people/tullis-c-onstott .

by Hemani Kalucha

Increasingly, experts are coming to the conclusion that if life exists or ever existed on Mars, we will only find signs of it far beneath the surface. There’s a brand new effort at JPL to create missions to Mars that go beneath the surface and you can read all about it here. As someone who hopes to be involved in the development of such a mission, I thought it would be a good idea to talk to one of the world’s leading experts on life underground: Professor Tullis Onstott! Professot Onstott is a professor of Geomicrobiology at Princeton University and an incredible mentor to me! Read about all his exciting discoveries here, here, and here.

Green Shoots, Space Gardens

It's snowing in Toronto this morning. Seriously. But irrespective of what I see outside my window, I know spring to be near at hand. Many of us have experienced the therapeutic power of caring for and raising plants and are looking forward to getting out into our gardens. I for one need to have some greenery around my office and home, which marks me as a bit unusual. In space, however, plants may eventually serve a more vital role. This week Alex examines the first green shoots researchers are cultivating along that pathway. Above, a zucchini plant is pictured on the ISS. 

by Alex Innanen

Spring is arriving in fits and starts in Toronto, and that means it’s time to start this year’s seeds and get out in the garden. It would also normally be time to visit a nursery (or five) but this year is a bit different, and my gardening routine has been disrupted by isolation. Which got me thinking about growing plants in an even more isolated location – that’s right, it’s time for space plants!

I know that taking care of my plants, spending time in the garden, can be very relaxing and grounding. The same is true for astronauts. But we haven’t been growing plants in space just because they’re nice to work with. One big reason to grow plants in space is for food. On the ISS, it’s relatively simple to resupply the astronauts with fresh food but think back to early explorers spending months at sea and getting scurvy. If only they had had a grow light and some arugula! Plants have also been suggested as a from of life support – we know that plants recycle carbon dioxide into oxygen, the kind of reverse of what happens in animals where we breathe in oxygen and exhale carbon dioxide. In addition, wastewater can be used to grow plants, and the same plants then transpire, or release, clean water vapour, which can be condensed and used again.

Why do scientists get things wrong?

By Dr. Christina Smith

It occurred to me over the last couple of weeks that lots of people have found the changing information and guidelines, recommendations, and findings on COVID-19 to be surprising, sometimes frustrating, and perhaps don’t understand why things can change so rapidly. I’ve heard things like “why should I trust this information if its different to last week’s?” I’m not an epidemiologist or any kind of bio-anything scientist so that’s the only thing I’ll be saying about COVID-19. But, it dawned on me that perhaps it isn’t completely clear that people at the forefront of any field in science are really piecing together bits of information and evidence the best way they can to try and figure out what is happening. With time and enough information the explanations (often – not always) become more and more in agreement but with newer problems and smaller amounts of information, the findings that people come up with can vary wildly.

Intro to Infection Modelling

Like everyone else, the COVID-19 pandemic has drastically changed how our group operates and interacts. However, we've been luckier than others in our operations since relatively few projects that are currently active require access to the university experimental facilities which are now closed. 

Everyone has a different way of coping with the anxiety and stress that an unprecedented event like this one produces. For many scientists, there is a certain comfort in information. Sometimes the act of defining, modeling, classifying can make you feel as if you have more control over an uncontrollable situation and, at least, you might gain insight that might be actionable. 

The next two articles on this blog, submitted by the Postdocs, discuss the pandemic. The first, below, tries to consider the modeling of these systems. The second tries to grapple with the things that scientists get "wrong," by laying bare how piecing together a real-world puzzle from incomplete information can sometimes lead to dramatic shifts in our understanding of how these systems operate. In times like these, the public often turns to scientists for advice and it's important to remember that none of us has a crystal ball.

Wherever you are, I hope you are as safe and secure as you can be and are managing the physical and mental toll. No matter your circumstances you aren't alone in this.

by Dr. Paul Godin

With the COVID-19 pandemic drastically impacting our day-to-day lives, I thought it worth examining how epidemiologist model infections and how social distancing can “flatten the curve”.  (Note, this idea was inspired by Peter Taylor, who provided the initial matlab code to run the simulations)

Characterizing the atmosphere of exoplanet K2-141b

 

The image above (Credit: ESO/L. Calçada) shows CoRoT-7b, an exoplanet located so close to its parent star that the input of radiation causes the surface to melt. It is for this reason that these strange worlds are called "Lava Planets" and they have unique atmospheres that are made up of rocky vapours. PVL PhD student Giang Nguyen has been working on understanding how a similar world, K2-141b, operates in collaboration with Prof. Nick Cowan at McGill University. There will be a paper out soon, but Giang provides a preview of the work below.

by Giang Nguyen

K2-141b belongs to a subset of rocky planets that orbit very closely to their star and are tidally locked. The dayside of the planet is hot enough to not only melt rocks (about half the planet is one giant magma ocean, hence the name lava planet) but to vapourize them as well. This vapourization process ultimately creates a thin atmosphere that may be detectable from hundreds of light year away with the right space telescopes.

For my work, I have been using computer models to simulate the atmosphere of K2-141b. I considered two cases: a sodium atmosphere and a silica atmosphere. Sodium is chosen as it is the most volatile component in minerals while silica is chosen as it is expected to be the most abundant for rocky planets. The atmospheric model is based on the shallow-wave equations with steady-state flow driven mainly by the temperature contrast between the planet’s permanent dayside and nightside hemispheres. As expected, since sodium is much more volatile, the pressure of the sodium atmosphere is more than 50 times that of the silica atmosphere. This also allows the sodium atmosphere to exist beyond the day-night terminator while the silica atmosphere collapses just before this point. However, as sodium has a lower heat capacity than silica, the sodium atmosphere cools off much faster which has implications for observations. In either case, the wind exceeds 1.5 km/s which is useful for high-dispersion spectroscopy.