Warning: In solar observing, safety is always paramount. Retinal eye damage caused by the sun is permanent. Always make sure your telescope is properly filtered and that your filter is undamaged before looking through it. Cap off any unfiltered optics such as guide scopes.

For the 4th of July, solar observers got a gift: an honest-to-goodness large chain of sunspots. Composed of twelve spots in all, the chain – the second decent chain in two months – seems to promise that the sun is at last coming out of its long nap.

So if you’ve been thinking about solar observing and how you might get started, now is the time. You have a number of excellent options:

• Free: use US tax dollars to observe the sun in striking detail, in time lapse movies and in many different spectra, using the SOHO (SOlar and Heliospheric Observatory) space telescope.

• Very inexpensive: Attend the Cranbrook Institute of Science’s First Sunday Solar Observing – the first Sunday of every month from 1 to 4 PM, weather permitting. Use their historic telescope, filtered using special filters that allow you to see all sorts of details on the sun’s surface that you can’t see otherwise. The only cost is admission.

• Inexpensive: Make a filter using Baader AstroSolar material, at about $35 per 10×10 sheet. You must make sure the filter material is free of any scratches, creases, or holes for safety’s sake, and make sure to store the filter carefully.

• Moderate: Buy a full-aperture glass or pre-made Baader filter, for $80-$200 depending on size.

• Expensive: For approximately $500, you can buy a “starter” Hydrogen Alpha telescope, such as the Coronado Personal Solar Telescope or the Lunt Solar Systems LS-35. These are very small telescopes, but do show the sun very nicely.

Should you get a glass filter or a Baader film filter? There are a number of things to think about:

• Glass filters are fairly sturdy, feel solid, and look very nice. They’re not too expensive, and should last a long time.
• Baader filter material is a thin film that seems very fragile. It’s tension-mounted in a cell that fits around your telescope’s front end. Baader filters must be handled with care and properly stored to avoid scratches, creases, or any other damage.

The difference is that Baader filters transmit the full visual spectrum, while glass filters only transmit the lower-end, towards the red side. This means that you can see details through the Baader – such as faculae – that are not accessible through glass filters. It’s still nowhere near H alpha, but much closer.

Furthermore, Baader filters are diffraction-limited, meaning they don’t degrade the image at all. Glass filters are by nature somewhat low-resolution. If you’re interested in taking photos or observing sunspots at high magnification, that’s a big concern. It comes down to whether risk/liability/ease of maintenance or seeing as much as well as possible is the first priority.

So once you can safely observe the sun, what will you see? More on this next time.