It is time to talk about my favorite celestial object: THE SUN! Although it looks like a uniform glowing orb in the sky, the sun actually is very dynamic and very violent. You may have heard that Earth’s magnetic field protects us from solar weather and you might have thought WAIT what exactly is that? Are there thunderstorms on the Sun? How does it get here? Well, no, there are no thunderstorms on the Sun, but what is actually going on there is much more intense.
There are a lot of phenomena that come from the Sun and fall under the umbrella of solar weather including solar flares, coronal mass ejections, solar wind, sunspots, and solar prominences. The first two can have a huge impact on Earth and our functioning technologies but the others are pretty cool to learn about too!
Let’s start with solar flares which are large bursts of radiation from the Sun’s atmosphere; they appear as flashes of white light. Lucky for those of us on the Earth’s surface, Earth’s magnetic field protects us from this radiation. Astronauts, especially those concerned with deep space travel like the mission to Mars, do not have the same protection. So solar flares are a big issue when talking about the health risks involved in sending people to the red planet. Although the radiation doesn’t reach the Earth’s surface, it affects our lives down here by inhibiting radio communication between satellites and damaging the equipment.
Coronal mass ejections (CMEs) are the big bad when it comes to solar weather. A CME is an eruption of magnetized particles that burst from the Sun. CME particles can make their way pretty close to Earth, even touching down on the Earth’s surface. Although Earth’s magnetic field blocks most of the particles as it does during a solar flare, a CME can upset Earth’s magnetic field and some particles can make their way towards the poles. While the particles which reach the atmosphere, exciting it, lead to the beautiful light show known as the Northern and Southern Lights, these particles can also disrupt power grids of those regions. This is in addition to the disruption of satellite radio communications. Unlike a solar flare which can be easily visible on the Sun’s surface, a CME isn’t particularly brilliant and is best seen by blocking out the Sun’s natural light; NASA and ESA’s SOlar Heliophysics Observatory (SOHO) does this in the images below.
Now for the rest of them. Ready, Set, GO! Solar wind is the general term for the steady stream of particles the Sun emits and includes the storms known as solar flares and CMEs. Sunspots are regions of darker, cooler plasma on the Sun and appear to us as a spot. We know that they don’t really affect the Earth that much though because their 11 year cycle doesn’t show any correlation to Earth’s climate’s history. They are also fairly easy to observe on a solar telescope. Solar prominences which are larger than the size of Jupiter are arcs of gas that leave the Sun’s surface. A solar prominence can erupt into a CME but it also can just sink back into the Sun. We actually saw one during the most recent Solar Eclipse which is shown as the pinkish color at the top left of the photo below.
So what makes the Sun tick? What is causing these events to unfold?
Similar to how the Earth has a magnetic field from the movement of its core during Earth’s rotation, the Sun has a magnetic field from the Sun’s movement… which is a bit more chaotic. Since the Sun has no solids, different areas of the Sun rotate at different speeds, the equator being the fastest. This can cause the magnetic field to ravel up on itself. When it sometimes binds up too much, the region bursts and the magnetic field realigns itself. Pretty crazy, right? Sunspots are not so chaotic in nature; they are regions where you can see the magnetic field breaking out of the Sun and thus always come in pairs (a north and a south pole).
If you ever have the chance to get to see the Sun through a solar telescope, I highly encourage you do. It is a fascinating entity! If not, NASA shares many different images of solar weather on their site, so be sure to check that out. Although constantly being called out for being an “average star”, the Sun is ours and provides us with so much information with how stars work which makes the Sun in my book spectacular.