In March 1989, a powerful eruption from the Sun slammed into the Earth’s magnetic field and took down a regional power grid in Canada, plunging the entire province of Quebec into darkness. Although such dramatic examples of “space weather” are relatively rare, the Sun emits a steady stream of radiation and charged particles that have the potential to disrupt our increasingly technological society. Boulder is home to the Space Weather Prediction Center (SWPC) at NOAA, as well as numerous scientists at the National Solar Observatory and NCAR who study the root causes of solar eruptions and their resulting impacts on our planet.
When Galileo projected the Sun through his telescope, he marveled at the dark spots that littered its surface. We now know that these sunspots are areas where the magnetic field is stronger, making the spot cooler and darker than its surroundings. Careful records of sunspots over decades revealed a regular rise and fall in the number of spots every 11 years. This is the most visible manifestation of an underlying magnetic cycle in the Sun, where the magnetic bubbles that appear as sunspots at the surface are periodically stretched out, reorganized and recycled by rotation and other motions deeper in the interior.
Although solar eruptions can happen at anytime, they are stronger and more frequent around the peak of the Sun’s magnetic cycle. As the magnetic field around sunspots emerges from the surface, it sometimes gets twisted and tangled with the field of neighboring spots. This can create sudden bursts of energy, ejecting hot gas out into the solar system.
Such events are a spectacular sight for NASA telescopes when they happen on the east or west limb, but they evoke different emotions when they occur on the side of the Sun that is pointed directly at Earth. A few days after an eruption, charged particles will slam into the Earth’s magnetic field, spiral into the atmosphere near the poles, and interact with oxygen and nitrogen to produce shimmering curtains of light in the sky.
“Everyone is aware of the northern lights and how beautiful they are. That’s something that I have always been captivated by,” says Ryan McGranaghan, a recent PhD in the Aerospace Engineering program at University of Colorado at Boulder. After coming to Boulder in 2011, McGranaghan collaborated with scientists at NCAR’s High Altitude Observatory (HAO) as well as SWPC at NOAA while working on his doctoral thesis. He now has a fellowship to work at NASA’s Jet Propulsion Laboratory in Pasadena starting next year. He credits a class taught by HAO research associate Delores Knipp for sparking his interest in space weather.
“All of this energy from the Sun is coming into our atmosphere and having adverse effects on the safety of our space infrastructure,” he says. “The more we’ve started to rely on technologies that are space-based, the more susceptible we’ve become to space weather.”
Some readers may remember a time when we used printed maps and road signs to find our way from one place to another. In the age of the smart phone, the Global Positioning System (GPS) is now integrated into our lives. It’s easy to forget that GPS relies on a network of 24 orbiting satellites that communicate with receivers on the ground. Space weather events can distort GPS signals as they travel through the atmosphere, reducing the accuracy of your calculated position.
Similar problems can arise with many types of satellite communications, including increasingly popular satellite radio and television signals. But the impacts of the associated radiation can extend beyond these inconveniences. After strong solar storms, astronauts on the International Space Station take extra precautions and commercial airlines are diverted to lower-latitude routes to avoid dangerous exposure.
If you’d like to learn more about space weather, McGranaghan will be speaking at this month’s Ignite Boulder event. Ignite presentations are often compared to TED talks, but they have a unique format. Each speaker has 5 minutes to present 20 slides that are set to advance automatically every 15 seconds. The concept originated in Seattle, but it has now been replicated at thousands of events around the world.
“The American Geophysical Union now does an Ignite event, and I’ve also been to one at NCAR,” says McGranaghan. The local events take place several times a year at Boulder Theater, and have always sold out. All of the talks are eventually posted online, so you can watch until the next solar eruption brings down the power grid.