The Sun’s magnetic field is measured to be approximately 0.15 Tesla, much larger and more complex than Earth’s. This intensity combined with its enormous size, allows the sun’s magnetic influence to extend beyond the farthest planet in our solar system. But, how is this gigantic field generated?
The Sun is made up of plasma, a state of matter with such high temperatures that electrons become separated from their atoms, forming ionized gas. When these charged particles rapidly move around, they naturally create magnetic fields, which in turn affect how these particles move. This creates a cycle that sustains the Sun’s magnetic field through the flow of plasma, a process called the solar dynamo.
The basic shape of the Sun’s magnetic field is similar to a bar magnet. Closer to the surface, however, the fields get twisted and complex. The tangledness and intricacy of these local fields are caused by differential rotation. This means that the plasma on the equator of the sun moves faster than the plasma near the poles. Over time, this causes the magnetic field to get entangled.
Analogous to rubber bands, with enough rotations and buildup of energy, the field eventually “snaps”. The spots where the field snaps are regions where solar activity occurs. This includes:
- Sunspots: areas where the field is so strong that energy cannot reach the surface of the sun. They come in north and south pairs just like magnets.
- Solar Flares: sudden explosion/release of x-rays and energy due to constantly moving and reorganizing of magnetic fields.
- Coronal Mass Ejections (CME’s): release of immense clouds of particles and energy due to sudden reorganization of the magnetic field (usually accompany solar flares).
Although the Earth’s magnetic field protects us from the constant stream of particles from the Sun, when solar activity ramps up, different effects arise. The energy from flares can affect radio waves in the atmosphere, which affects communication signals and may cause temporary blackouts. The particles released from CME’s can interact with oxygen and nitrogen on Earth, creating the aurora. Along with this, GPS coordinates can drift a little, electrical systems can overload and astronauts aboard the ISS could get injured, especially if they are conducting a spacewalk.
The complexity and effects of solar activity changes depending on where the Sun is in its solar activity cycle. Every 11 years or so, the north and south poles of the Sun switch! This switch occurs at solar maximum, where activity on the sun is at a peak. In contrast, solar minimum is where activity on the sun is at its lowest point. This flip sends a ripple across the heliospheric current sheet (surface of the Sun where the north and south poles switch and a really tiny current flows). This means that the effects of solar activity on Earth become more frequent as Earth passes through this ripple more often.
Solar wind from the Sun extends the magnetic field to a massive extent. The region where our Sun has influence is called the heliosphere. Similar to how Earth’s magnetic field protects it from solar activity, the Sun’s magnetic field protects all the planets from galactic cosmic rays! It has also been recently noticed that the Sun’s magnetic poles are out of sync! Last Sun cycle in 2013, it was observed that the North pole was moving faster than the South. This meant that the Sun had 2 South poles for a brief period of time!
Below is a brief infographic summarizing all of this!