The SOlar Cycle
The Sun looks the same every day. But looks can be deceiving.
Beneath that steady glow, our star is constantly churning. Its magnetic field winds up, tangles, and resets on an 11-year cycle, driving dramatic changes across its surface: dark sunspots appear and multiply, loops of superheated plasma arc thousands of kilometres into space, and bursts of energy ripple all the way to Earth. This is the solar activity cycle, and your students can discover it for themselves using the same real data that astronomers use.
This inquiry-based guide gives secondary school students direct access to archival images from NASA's space-based solar observatories. Through guided exploration, they learn to read scientific images, distinguishing visible from ultraviolet light and interpreting false colour, and then use those skills to uncover one of the Sun's most fascinating long-term patterns. No telescope required.
Getting started!
You'll want to download and read through the whole guide. These activities are meant to flow naturally into one another.
This guide is designed for pairs of students in Grade 7 and up, and works best when each pair has access to a computer or tablet with an internet connection. If that's not possible, the activity can also be run as a teacher-led demonstration using a single computer and a projector.
Before you begin, it's worth knowing that Parts 1 and 2 are optional: if your students are already comfortable with false colour imaging and ultraviolet light, you can skip straight to Part 3. The final part is an optional extension for classes that want to go deeper into the connection between the solar cycle and life on Earth.
This is an inquiry-based activity, which means students are given real tools and real data and asked to direct some of their own learning. The guide scaffolds this process carefully, but it's worth preparing your students for the idea that there isn't always one right answer or a single path to follow. That openness is the point. Students who embrace it tend to get the most out of the experience.
Breakdown OF ACTIVITIES
UNDERSTANDING THE SUN'S LIGHT
Parts 1 & 2
Before diving into solar data, students need two key ideas: that scientific images are often taken in wavelengths invisible to the human eye, and that the colours in those images are chosen to encode information, not to reflect reality. These two optional activities build that foundation using familiar, everyday examples before turning to the Sun. If your students are already comfortable with false colour and ultraviolet imaging, you can skip ahead.
DISCOVERING THE SOLAR CYCLE
Parts 3 — 5
This is the heart of the guide. Students begin by writing down what they think they already know about the Sun's surface, then load up Helioviewer, a free web-based tool that gives them access to decades of real images from NASA's solar observatories. From there, they explore on their own, comparing the Sun across different wavelengths and different years, until the 11-year pattern of activity begins to emerge from the data.
ASKING YOUR OWN QUESTIONS
Parts 6 — 8
With the solar cycle in hand, students turn their curiosity into research. They generate their own questions, learn to evaluate which ones are scientifically investigable, and then pursue an answer using Helioviewer. The activity wraps up with a class discussion, peer sharing, or written summary. For classes that want to go further, an optional extension connects the solar cycle to auroras, satellite infrastructure, climate, and other real-world phenomena.
classroom-ready slides
We’ve created ready-to-use slide decks to make sharing these themes with your students easy and engaging. Just download the Google Slides Presentation (in whichever format you prefer), then customize anything you’d like so it fits your teaching style and goals. You’ll also find a few hidden slides with extra tips, plus speaker notes to help guide your flow. The guides are there to build your confidence and understanding, while the slides are all about bringing that learning to life in your classroom.
image gallery
Here you can download all the images from the guide to use as you wish. If you're sharing something of your own, unless noted otherwise in the guide please credit Discover the Universe and link back to this webpage.
SUPPORT
These activities hold a special place in our history, being the very first full guide we published! These activities still sit at the heart of what we do, even 15 years later. We think everyone should head outside to to look up, and we hope your students enjoy learning all about the foundations of our sky!
Should you run into any trouble, or need advice on any activity in particular, please feel free to reach out to our team and we'll get back to you with support as soon as we can!