Space Umbrella

Earth’s Magnetosphere: A Space Umbrella for Space Weather

An artist’s drawing of Earth’s magnetic field (blue lines) interacting with the Sun’s solar wind (orange lines). Credit: NASA

The Sun constantly sends out energy and streams of charged particles, known as the solar wind. These bursts can be powerful—and sometimes risky—for people and technology on Earth. But Earth has a remarkable defense system: the magnetosphere, an invisible barrier shaped by our planet’s magnetic field. It pushes away most of the Sun’s radiation and particles, even as the solar wind rushes through space. This protective shield plays a major role in keeping Earth safe from the Sun’s intense space weather, making our planet a much more secure place to live. That’s why we call it a “space umbrella” — it helps protect Earth from the Sun’s space weather.

The different impacts of Space Weather on Earth. Credit: NASA/NOAA

When the solar wind reaches Earth’s magnetosphere, some incredible things can happen. This interaction creates the glowing northern and southern lights (the aurora). Big bursts from the Sun can also generate strong geomagnetic storms that disturb GPS and communication systems. Scientists study how the solar wind meets our “space umbrella.” By doing this, they can predict solar events and protect astronauts and technology. They can also discover how other planets use their own magnetic shields.

The Magnetopause: A Natural Laboratory for Plasma Physics

Cartoon showing the locations of the solar wind, sheath, magnetopause, boundary layer, and magnetosphere. Note: figure not to scale.

Understanding how the "Space Umbrella" and the solar wind interact starts with three important regions: the magnetopause, the boundary layer, and the magnetosheath. The cartoon above shows what these regions look like.

The magnetopause is the shifting border where the pressure from Earth’s magnetosphere balances with the solar wind. Inside this border is the magnetosphere. Most of the particles here originate from Earth’s atmosphere, and Earth’s magnetic field forms a closed bubble around them.

Outward of the magnetopause is the magnetosheath (shortened to "sheath"). The particles in the sheath mostly come from the Sun, but they are already affected by Earth’s magnetic field. You can think of Earth’s magnetosphere like a rock in a stream. As the solar wind flows around it, a “bow shock” forms in front of Earth, slowing and heating the solar wind. This heated solar wind makes up the sheath.

The magnetopause isn’t a sharp divider. Around it is the boundary layer, where particles from the sheath and the magnetosphere mix. This is where the solar wind and Earth’s magnetic field can become tangled together. That process is called magnetic reconnection. It can give solar particles extra energy and allow them to enter Earth’s magnetosphere. At the same time, some particles from the magnetosphere can cross into the sheath and escape into space.

During strong space weather events, magnetic reconnection can become much more intense. The magnetopause can even move closer to Earth, sometimes inside the orbit where satellites normally fly. These extreme events can cause a lot of particle mixing and energizing. They can damage satellites and create auroras that appear as far south as Texas or Mexico.

Scientists want to know how solar wind particles get into Earth’s magnetosphere and how the particles inside it change. This area of space helps them understand space weather and magnetic reconnection. They use the magnetopause and the boundary layer like a natural science lab in space.

NASA’s MMS Mission: Unlocking the Magnetosphere’s Secrets

Artist rendition of the MMS spacecraft probing the Earth's magnetosphere. Credit: NASA

NASA’s Magnetosphere Multiscale Mission (MMS), launched in 2015, uses four spacecraft flying together to study the edges of Earth’s magnetosphere. Its main goal is to understand magnetic reconnection.

In this project, you’ll look at data from an instrument aboard MMS called the Fast Plasma Investigation (FPI). It counts charged particles and measures their energy. The images you see show how many particles are hitting the detector at different energies. FPI data helps us know which region the spacecraft is in. That’s because the charged particles in the magnetosphere look different from the ones in the sheath.

Crowdsourcing: The Key to Identify the Magnetopause and Boundary Layer

An example 10-minute observation from NASA's MMS mission with expert classifications. MMS starts the observation in the pure sheath (on the left), moves into a region that have both signatures of the sheath and magnetosphere (shortened to MSph) before settling in the pure magnetosphere (on the right). Check out more expert-labeled observations in the "Field Guide".

Over its 8 year mission, our team has identified over 5,000 times when MMS observed the magnetopause. We used a machine learning algorithm that we trained to distinguish between the different plasma signatures in the FPI data. But we noticed that our algorithm gets confused during the boundary layer. This is because the data looks like a mix of both the sheath and the magnetosphere.

That’s why we need the help of volunteers like you. The human eye is still much better at finding when MMS is within the boundary layer than our current machine learning model. By combining the answers from many volunteers, we can get a more reliable idea of when MMS enters and exits this region. By the end of the project, we will create the largest-ever collection of magnetopause and boundary layer observations validated by humans. This new dataset will help space scientists better understand how the Sun and Earth’s magnetic field interact.

Interested in joining the Umbrella Squad?

Look through the tutorials and field guide before you start classifying. Feel free to ask questions about the science or the classifications in our discussion boards. We list some resources to dive deeper into any of these topics on our Education page. Check back often--we will share our results as we get more and more classifications. Thank you for helping us defend the Earth!

This work is funded by NASA. Learn more about NASA Citizen Science projects and how you can get involved.