Hi, I’m Marley, the Astronomer here at the Space Centre.
Now that its July, I’m excited to spend more time out in the sunshine. As things start to warm up, I find myself wondering: just how much does the Sun affect us? We take steps to protect ourselves from the UV rays that could give us a nasty burn, but is there anything else we should take into consideration?
Our Sun, like other stars, is a ball of hot gas made up of the elements hydrogen and helium. In its core, nuclear reactions provide the force necessary to keep it from collapsing in on itself due to its gravity. Most of the information we have focuses on the parts we can see: the photosphere, chromosphere, and the corona.
The photosphere is the visible ‘surface’ of the Sun. It is not a surface like like Earth’s; it is a layer of gas about 300km thick. This layer of the Sun is where we see sunspots – dark spots on the Sun that come and go. The chromosphere is the beginning of the Sun’s atmosphere. Its temperature increases the further away from the Sun you get and scientists are not sure why.
The corona is the outermost layer of the Sun. It is that white, wispy part you see during a solar eclipse. Its temperature is about 500,000°C, and it gradually turns into the solar wind. This solar wind is constantly travelling and hitting Earth. In fact, aurorae are a consequence of this interaction. Highly energetic particles in the solar wind get caught in our magnetic field, and then interact with particles in our atmosphere, giving us those brilliant lights at the poles, and occasionally as far south as Vancouver. But the Sun can cause more than pretty lights on Earth.
Picture it: Earth. The last few days of August, 1859. Suddenly, the telegraph system (the Victorian era internet) starts to go on the fritz. There were reports of fire coming out of the circuits of the telegraph machines. Come September 2nd, it became impossible to send or receive messages unless the machine’s batteries were unplugged. Messages could be sent from Massachusetts to Maine using just the current in the air. Nothern lights were reported as far south as Jamacia, and the sky got so bright that people got up early in the morning to begin work. This geomagnetic storm would become known as the Carrington Event, named for the amateur astronomer Richard Carrington who witnessed the cause of this event: a cluster of dark spots on the surface of the Sun, and the two patches of bright light that came out of them.
This bright light that Carrington saw is what is known as a solar flare. These are bursts of radiation due to the release of pent-up magnetic energy located in sun spots. What made the Carrington event so devastating was the accompanying Coronal Mass Ejection, or CME. A CME occurs in the outer atmosphere of the Sun. Parts of the Sun’s magnetic field, usually above sunspots, will have eruptions of gas, plasma, and the magnetic field itself. This eruption is a CME. The magnetic field that the CME carries hits our magnetosphere, and the two interact. This, in turn, disrupts the electrical grids that societies have built. How can we look out for CMEs, and know if they are going to impact us?
There is currently a whole fleet of NASA missions studying heliophysics, the physics of the Sun. This fleet is referred to as the Heliophysics System Observatory. The spacecraft vary in position; some very close to Earth and others are closer to the Sun. Current missions are the Parker Solar Probe and the Solar & Heliospheric Observatory, or SOHO.
The Parker Solar Probe, launched in 2018, is actually flying through parts of the Sun’s corona – seven times closer than any other spacecraft before it! Scientists want to learn how energy and heat move through the corona, because doing so may explain why it is so hot. Additionally, they want to learn just what moves the solar wind. Understanding this can help scientists protect the satellites we use.
SOHO is a mission that has exceeded expectations. Launched in December 1995, its mission will hopefully continue until 2025. SOHO has discovered lots of new things: 3000 new comets, solar tornadoes, and even detailed measurements of the temperature in the Sun's interior. SOHO is a very unique spacecraft because it has a coronagraph; a special instrument that blocks out light from the Sun so that it can actually make observations of the corona. It can also give up to three days' notice of any solar disturbances headed for Earth.
So, as we head into summer check out some of these activities and enjoy the sunshine. We’ll be fine!
Make your own hand print art with a little sunscreen and the Sun. If you have two different strengths of sun screen experiment with them to see how it might affect your print.
Monitor solar storm activity with your own magnetometer which measures changes in Earth’s magnetic field caused by solar storms.
Make your own solar flip book to see how solar flares erupt.
Read about how to safely look at the Sun and then make your own safe solar viewer to see if you can see sunspot activity. REMEMBER – never look directly at the Sun!
Contribute to the citizen science project, Aurora Zoo, and learn more about aurora and how they are formed.