Our Sun is an enormous ball of hot, electrically charged gas. As this gas churns through the star, it generates a powerful magnetic field. Every 11 years or so, this magnetic field flips, meaning that the Sun’s north and south poles switch places. It’s all part of the solar cycle, the regular variation in the Sun’s activity. At the peak of the cycle, called solar maximum, the Sun is busy with eruptions and often covered with active regions known as sunspots. At its low, solar minimum, the Sun is relatively calm. While this trend is fairly consistent, there is dramatic variation in activity between solar cycles. Some have lots of sunspots and activity while others are much quieter.
Activity on the Sun, such as giant eruptions like solar flares and coronal mass ejections, send powerful bursts of energy and particles into space. It causes the aurora, interferes with satellite signals, and poses a threat to astronauts in space. Scientists work hard to improve our ability to predict the strength of solar cycles so we can better plan and prepare for space weather events, much as we do with weather here on Earth.
Lisa Upton is a solar scientist based in Colorado. She works at the Space Systems Research Corporation and was co-chair of the Solar Cycle 25 Prediction Panel, a panel of experts sponsored by NASA and NOAA, the National Oceanic and Atmospheric Administration, that met in 2019. She uses modeling to understand what’s going on with the Sun, and she loves making solar cycle predictions.
(The following interview has been edited for length and clarity.)
What do you study?
I study the evolution of the magnetic field at the Sun’s surface. Turbulent convection in the Sun’s interior constantly twists and pulls out the magnetic fields that are deep in the Sun’s convection zone. I have a specific type of model which simulates the evolution of the magnetic field at the surface. I use this model to try to understand what’s going on in the Sun and to make predictions about upcoming activity – where and how strong it will be. I can predict how active regions are going to evolve over weeks, and I also try to make predictions on solar cycle timescales, which are about 11 years.
Most of our observations are focused on the Earth-facing side of the Sun, but we can use models to simulate the evolution of active regions on the far side of the Sun so that when they come back around, we kind of know where they are and what they’re doing.
How did you become a solar physicist?
I was at the University of Memphis working on a double major in electrical engineering and physics, and I did a student exchange program in Hawaii. I was active in the astronomy club there, and I volunteered and interned at the visitor information station doing Star Tours and talking with tourists about the cosmos.
After that experience, I wanted to do astrophysics. The only astrophysics research at my university involved studying the Sun. I told the professor, “I want to work with you.” At first, I thought of the Sun as a ball of gas that floats across the sky not really doing much, but as I learned about it, I discovered that it’s a really dynamic place.
My undergraduate advisor helped me arrange an internship at NASA’s Marshall Space Flight Center. It was an amazing experience. We measured surface flows on the Sun which was cutting-edge at that time, and the work resulted in a paper in the journal Science. Solar physics is a young science, so there’s a lot to explore and discover.
What’s your favorite part of your job?
My favorite part is doing solar cycle predictions. We make predictions by looking at how strong the Sun’s polar magnetic fields are. The polar fields that the Sun starts with at the beginning of the solar cycle are the seed to the cycle. The bigger the polar fields are at the beginning, the bigger the cycle will be.
I was a co-chair of the Solar Cycle 25 Prediction Panel. That involved looking at the solar physics community’s predictions and trying to determine what Solar Cycle 25 will look like. NASA has convened prediction panels for the last several solar cycles, but this cycle is going to be the best test of our models so far.
Credits: NASA’s Goddard Space Flight Center/Joy Ng
Download this video in HD formats from NASA Goddard’s Scientific Visualization Studio
What’s something you think about as a solar physicist that many of us might not realize about the Sun?
The poles are the last unexplored regions of the Sun. We go around the Sun every year, so we’ve seen everything that’s going on around the equator, but the polar regions are not well understood. For us to understand what’s going on in the interior, we’re going to have to view the Sun from different vantages. We need to get above the Sun because these polar fields are crucial to understanding the solar cycle and measuring how the Sun’s surface moves at high latitudes.
How does being a solar physicist affect how you think about our place in the universe?
The Earth seems big to us, but it’s tiny compared to the Sun. And the Sun is not that big a star. Then you realize we’re just one little solar system in this galaxy that’s composed of billions. We’re a tiny rock in this vast universe. The enormity is just mind-blowing to me.
We are challenging all our preconceived notions, and we are finding things that we never even dreamed of. There’s so much possibility out in the universe.
Banner image: The Sun goes through an 11-year cycle of changing activity called the solar cycle. The image on the left shows a calm Sun, while the image on the right shows a more active and varied solar atmosphere as the Sun moves closer to peak solar activity. Both images were captured by NASA’s Solar Dynamics Observatory. Credits: NASA’s Goddard Space Flight Center
By Anna Blaustein
NASA’s Goddard Space Flight Center, Greenbelt, Md.