It is an indisputable fact that the Earth hurtles around our Sun at 30 kilometres per second, but it sure seems to speed up during the summer. School is out, friends and family gather for bonfires and barbecues… time flies when you’re having fun.

Of course, the cosmos ticks along at its usual pace regardless of season, and the science of decoding the universe never truly takes a holiday, either.

As students and teachers in the Northern hemisphere prepare to head back to school, we decided to take a look at some of the biggest physics stories of the summer — and provide some handy primers to help you brush up on what you may have missed while you were dozing in a hammock.

The heat is on

What happened? The summer of 2018 has been one of the top-four hottest on record (along with 2017, 2016, and 2015 — notice a trend?). This scorcher of a summer has seen unprecedented heat waves, floods, wildfires, and droughts. New research published this summer in the Proceedings of the National Academy of Sciences suggests we may be at the cusp of a tipping point in climate change that would create a disastrous “hothouse” climate on Earth.

So what? The increasingly steamy summers are no mere happenstance. They are the result of climate change, and “the impacts of climate change are no longer subtle,” Michael Mann, a climate scientist and director of the Earth System Science Center at Penn State University, told CNN. That means our turbulent climate is poised to spark more disasters, disrupt more lives, and drive climate refugees to mass relocation — among many other crises both known and not-yet-foreseen.

What’s the deal, scientifically? Climate change is fuelled by greenhouse gases, such as carbon dioxide, trapped in the Earth’s atmosphere. Accelerated by human industrialization, this process traps in heat and raises average temperatures around the whole planet (no matter how chilly you might feel on a given day in February). This video, from Perimeter’s “Evidence for Climate Change” teaching resource for Grade 10 classes, provides an overview of the physics behind our warming atmosphere and some potential ways science can find solutions.

Download the “Evidence for Climate Change” and “Temperature Rising” resources for free.

Martian waters

What happened? The Italian Space Agency announced in June that researchers had found signs suggesting the presence of a large body of liquid water deep beneath the south pole of Mars.

So what? The notion that Mars might contain stores of liquid water — as it did in the past, evidenced by dried-up river basins — has tantalized researchers for decades. Water is the lifeblood of our planet, so its presence on our nearest planetary neighbour could mean we are not (or have not always been) alone in the universe, and would bolster the case for making Mars a second home for humanity.

What’s the deal, scientifically? The Italian team’s findings, published in the journal Science, are based on observations recorded by the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument (Marsis). Hitching a ride on the European Space Agency’s Mars Express spacecraft, Marsis bounced low-frequency waves off the red planet, gleaning geological data from the returning signal. Although no one can say with certainty that Marsis glimpsed wet water under the south pole, the 12-mile-wide “well-defined anomaly” sure looks lake-like.

For humans looking beyond our planet for hospitable future homes in the cosmos, Mars is top of the list. The presence of liquid water would certainly strengthen the case for habitability, but getting to Mars — and staying there — presents an enormous list of scientific and technological challenges.

This video, excerpted from Perimeter’s “Mission Possible” educational resource, examines what it will take to make humanity’s next giant leap.

TESS glimpses “first light”

What happened? In the search for planets beyond our solar system, last spring NASA launched the Transiting Exoplanet Survey Satellite, affectionately known as TESS. After orbiting Earth for a while, it used the moon’s gravity to slingshot itself into a new orbit, where it is scanning the cosmos for other worlds. In late May, it beamed its first image back to Earth, and it is breathtaking:

So what? The image above is just a test — making sure the lens cap is off, and so forth — and it reveals hundreds of thousands of celestial bodies. And that’s just a tiny sliver of the night sky. Over the next two years, TESS will survey the rest of the sky, piecing together an image 400 times larger. In the process, TESS is expected to detect thousands of new exoplanets in our galactic neighbourhood, roughly 300 of which are expected to be Earth-like. Ultimately, the search for exoplanets may answer one of humanity’s oldest and most profound questions: are we Earthlings alone in the universe?

What’s the deal, scientifically? TESS uses the transit method of sleuthing out exoplanets, which involves measuring how the light emitted by stars changes when a planet crosses its orbit. Regular dips in the brightness of a star can indicate one or more planets zooming around it — and the intensity and duration of those dips can tell scientists about the size and shape of a planet passing by.

Perimeter’s educational resource for Grade 9 classes, “Figuring Outer Space,” includes hands-on activities that simulate the search for alien worlds.

Einstein was right! (Again!)

What happened? In June, an international team of scientists announced they had measured the motion of a star passing close to a supermassive black hole.

So what? The result confirmed a prediction of Albert Einstein’s general theory of relativity. That is a pretty huge deal for a few reasons. First, it verifies another aspect of Einstein’s century-old masterwork, which is our best model of how the universe works on large scales. It also demonstrates the incredible progress humanity has made in experimental astrophysics, making measurements that Einstein would likely have declared technologically impossible. Einstein “could not think or dream of what we are showing today,” said Frank Eisenhauer, senior astronomer at the Max Planck Institute for Extraterrestrial Physics. What’s more, the result is “the first step on a long road” to examining other facets of black holes, said team lead Reinhard Genzel.

What’s the deal, scientifically? Einstein’s general theory of relativity, published a century ago, predicted that the extreme gravity of a black hole would stretch light from nearby stars, causing it to appear redder (a phenomenon called gravitational red shift). The scientist focused their gaze on one star, called S2, which has a 16-year orbit. When it made its scheduled pass near a black hole, it sped up just as predicted by Einstein’s theory — reaching more than 25 million km/h, its wavelength shifting from blue to red.

This video from the European Southern Observatory beautifully explains the discovery:

As part of its suite of educational resources for classrooms, Perimeter Institute has created lessons and activities to help students and teachers delve into the universe’s gravitational dynamos, black holes. In the video below, Perimeter researchers Avery Broderick, Niayesh Afshordi, and Bianca Dittrich explain some of the remarkable characteristics of these powerful phenomena.

Quick hits

Science as cool as ice: In July, the IceCube Neutrino Observatory, Fermi Gamma-ray Space Telescope, and other telescopes around the world announced they had pinpointed a source of high-energy cosmic rays for the first time. The detection of a single high-energy neutrino called a “blazar” represented another leap in the fast-moving enterprise of multimessenger astronomy. Download Perimeter’s free educational resource about neutrinos, “Where Did All the Neutrinos from the Sun Go?”

In July, the IceCube Neutrino Observatory, Fermi Gamma-ray Space Telescope, and other telescopes around the world announced they had pinpointed a source of high-energy cosmic rays for the first time. The detection of a single high-energy neutrino called a “blazar” represented another leap in the fast-moving enterprise of multimessenger astronomy. Download Perimeter’s free educational resource about neutrinos, “Where Did All the Neutrinos from the Sun Go?” Galileo, onward and upward: Riding on a rocket launched July 25 from the European Space Agency’s Spaceport in French Guiana, four more Galileo satellites joined two-dozen of their peers in orbit around Earth. The Galileo satellites are the workhorses of Europe’s global navigation satellite system. The Galileo system is essentially Europe’s version of GPS, compatible with American GPS and Russian Glonass systems. While such technology is commonplace today, ubiquitous in smartphones and cars, it is only possible thanks to breakthroughs in theoretical physics made by Albert Einstein years ago. Download Perimeter’s free educational resource, “Everyday Einstein: GPS and Relativity.”

Perimeter Institute’s free digital resources are designed to help teachers explain a range of important physics and science topics, from astronomy and quantum mechanics to Earth Science, the process of science, and STEM careers. Visit the educational resource centre.