Astronomy Israel: Spotted Sun

Tuesday, November 8, 2011

Spotted Sun

The largest sunspot group in the current solar cycle number 24 is now visible in the center of the solar disk. This group is so large that you could fit 22 earths inside of it. It is also large enough to be visible to the naked eye as a tiny black "beauty mark" on the surface of the sun. Such large sunspots are not that rare as we approach the solar maximum, however, this has been an unusually quiet run-up to the solar maximum, which was originally expected in 2012 and may now be delayed. So, large sunspots have been rare so far in solar cycle 24. Scientists have not seen such low sunspot numbers for over a century, and the solar magnetic field, which produces sunspots, is at the lowest strength seen in over 50 years. There is even some fear that we may be entering a period of low solar activity comparable to the Maunder Minimum of 1645-1715 when the sun was spotless for 70 years and a mini-ice age occured. I guess that would put the kabosh on Global Warming, though.

However, the sun has recently been much more active, showing many spots and especially larger ones. Ancient Chinese astronomers reported seeing naked eye sunspots, viewing the sun through thin clouds. This made me want to take up the challenge of seeing naked-eye sunspots, too. As we approach the solar maximum these will probably become more frequent, but not common.

How do you do this safely? First of all, NEVER LOOK AT THE SUN WITHOUT EYE PROTECTION MADE SPECIFICALLY FOR THAT PURPOSE. YOU WILL DAMAGE YOUR VISION. IF YOU USE ANY OPTICAL AID WITHOUT THE APPROPRIATE PROTECTION, YOU WILL GO BLIND INSTANTLY. DO NOT USE SOME CONTRAPTION YOU HAVE MADE YOURSELF, LIKE FILM OR SMOKED GLASS.

Now that we've gotten that out of the way, here is what you can do. A number 14 welder's glass is safe to use in front of your eyes for naked eye viewing. This is what I use. You can buy one at any welding supply store. They are easy to find in the US, but I don't know how easy they are to find in Israel. I buy my solar filters from Thousand Oaks Optical in the US and have been very happy with them. They not only make filters for naked eye use, but also for binoculars and other optics such as telescopes and cameras. Even very small optics can show a great deal of detail on the sun, which you can either photograph or draw. This also makes an interesting project for schools. Another method to view the sun is solar projection, where a pin hole or small optic is used to project an image of the sun on a screen, such as a piece of paper. Be careful if you use projection with a small optic like a binocular that you don't inadvertently shine it in someone's eye.

Here is an image of today's sun, showing the gigantic sunspot group in the center. It will take approximately 10 days for it to rotate out of sight, and who knows, it may be followed by another.

Sunspot group 1339 at the center of the sun, the largest group yet in solar cycle 24.

A close-up of the right portion of the sunspot group taken by Alan Friedman in Hydrogen Alpha light, showing the magnetic field surrounding the group.

- by Ira Machefsky