Online Astronomy Society Academy
Solar Primer
Alastair Leith FRAS Your mission, should you choose to accept it is to Observe Sun Spots Safely
Warning!
You should never under any circumstances attempt to observe the Sun directly with or without a telescope as it could blind you.
Background
Our Sun is our nearest star. An inferno of energy that radiates heat 24/7. We may thing the Sun switches off when it sets, in fact now as our Earth rotates from our Dawn to Dusk it proceeds on to give daylight to another part of the world, while allowing you to rest taking around 12 hours for the next Sunrise.
Even though the Sun is too bright and hot to observe directly there are a lot of interesting things we can often see on the Sun which has had astronomers inspired for centuries. Before we look at what we could see on the Sun and how, lets first take a look at some fascinating Solar Facts Sun Distance 93,000,000 miles away Surface Temperature: 6000 degrees Celscius Diameter, 1,392,530 km (way bigger than our own planet!) Did you know it takes 8.5 minutes for light from Sun to reach us (so if the Sun died NOW, we would not know about it for at least 8.5 minutes! How does the Sun shine? Well its a little technical to explain, but the Sun has a lot of the gas Hydrogen which it converts to another gas called helium. When it does this ener-
gy is created. We call it nuclear fission. VERY hot temperatures are needed for this. Well the Sun is over 15 million degrees Celscius at its core, so plenry hot enough! In fact the Sun burns over 15 million tons of Hydrogen a second! Despite the obvious dangers of observing the Sun, there are good reasons to observe it. We can see things like Sun Spots for example.
Sunspots
On the Suns surface we get magnetic fields that are produced. Every so often these magentic fields get tangled, which slows the flow of energy to a region of the Sun. As a result that area cool a little and we see darker regions that form, called Sunspots. Although it is too dangerous to point a telescope at the Sun and look with the eye (NEVER do that it will blind!). We can however project the Suns image safely onto a piece of paper as see the Sun as a disc with Sunspots on it. A nice project is to sketch these with paper and pencil. In fact if your lucky enough to have Sunny days in a row you can see how these move across the Suns suface? In fact did you know, that some of these Sunspots become active regions. Which means as soon as the tangled magnetic field we spoke of earlier becomes untangled, it unleashes masses of stuff and energy. We call this a Coronal Mass Ejection. And guess what.. it is these which cause our Northern Lights. If you have seen these, they are like green, red, and blue lights in the night sky. They are caused by bits of the Sun hitting the upper Earths atmosphere.
What you need to observe Sunspots A refracting telescope (if you do not have one you might be able to borrow one) 2 pieces of paper Pencil Draw a 6 inch circle on one of the pieces of paper, this you can sketch on. The other can be used to project the Suns image onto as below (the Sun guard is useful but not essential (note if you have a finder on your telescope, please remove it)
Sketch by Catherine Leith
What you will see... What light view of the Sun, this is a photo not a sketch, but you can clearly see sunsots in this image. image by Steve Ward, Bucks The thing to note with Sunspots are the ones that are closest to the centre of the solar disc are the ones that if they relase a CME they will be sent in our direction. You can see above a group that closely fulfills this. In fact that group for time would have been in direct range as it rotates A closeup of the spots, note there is a lighter and darker area? The light area is the Penumbra, the dark is called the Umbra. You can make out some detail in the spots as well
Further projects and resources As discussed earlier in this booklet, if you have successive Sunny days, why not make regular checks of the Suns surface you can over time see how the Sun Spots move across the Suns disc. In time you might even be able to predict space weather going by how active Sun spots are. IF your really getting into it then checkout www.onlineastronomysociety.com they have a group on Facebook dedicated to Solar Astronomy For up to date images of the Sun see http://sohowww.nascom.nasa.gov/ If you would like to learn more about observing the Sun safelt, you can enrol on one of our coruses www.onlineastronomycourses.co.uk Starry Night - Planetarium Software www.starrynight.com
Other useful links Aamateur Astrophotography Magazine http://www.amateurastrophotography.net/ ideal for those getting interested in Astrophotography David Bood also writes an amazing sciency blogg http://www.icyscience.com/
Interested in learning more about Astronomy? Why not sign for our GCSE Astronomy Course www.onlineastronomycourses.co.uk Copyright notice This material remains the property of Online Astronomy Society Academy. This maybe printed for purposes of workshops and other resources run on a non profit making basis. If unsure please email OASAcademy@gmail;.com for more details