Hi there, my name is David Fuller, host ofthe â€œEyes on the Skyâ€� astronomy series. In this tutorial I'm going to talk about bothsafe, and unsafe ways to view our nearest star, the Sun.Let's start by talking about the safe methods to view the Sun. Probably the most popularway for amateur astronomers is to use a white light solar filter on the front of their telescope.These block 99.9% of the incoming light, so that the rays reaching the eyepiece whereyou view the image will not damage your eyes. The can be made of glass, or a thin plasticfilm â€“ but ONLY use the films made specifically for astronomy â€“ more on that later. Filterslike this are a great way to view sunspots,
and brighter sections on the Sun called â€œfaculae.â€�Another method is eyepiece projection. It works best with small refractors, otherwisethis requires a few precautions: Unless you have a reflector with an aperture stop likethis one, then make one, with a diameter of no more than 2 to 3 inches to avoid too muchsunlight entering the tube. Avoid solar projection altogether with a compound type telescope,like this. Remember that the incoming light is concentrated as it is focused â€“ muchlike a magnifying glass does. So only use the simple Huygenian or Ramsden type eyepieces,as the multiple lens eyepieces have cement in them, which can break down from the concentratedsunlight and mess up your eyepieces. Also,
because the sun is so bright, it doesn't hurtto use an aperture stop even on a refractor, like this. It's not like you really need togather more light! You will lose a bit of resolution, but better to be safe.Another way to view the sun is with a pinhole projection method. I won't go into detailon that here, but these are good to use for viewing solar eclipses, though the image theycreate is small, and can be dim. But it is a safe way to view the Sun particularly forsolar eclipses; it's just simple pinhole in something like aluminum foil, and held infront of a white sheet of paper. If you don't have a way to magnify the image,you can still see large sunspots or a solar
eclipse by viewing the Sun naked eye â€“ butonly with the proper protection. You can take a solar filter, hold it over your eyes first,then look up, like this. Another way is to use solar eclipse viewers, solar eclipse glasses,or even simple sheet of solar film and then look at the Sun. Welders glass can be usedtoo, but NOT anything less than 14 the 12, 10 and under are NOT safe, and stackingwelders glass is not safe either. ONLY use 14, or don't look at all.Here is a list of things that are absolutely NOT SAFE for solar viewing:Sunglasses, Multiple Sunglasses stacked together, Mylar Balloons, Mylar Food Wrappers, Â SmokedGlass, XRay Film, Film Negatives, CD's or
CDROM's, Stacked Welder's Glass, Liquid Filters,Coffee, Sun tea, Eclipse Glasses and Telescopes Together or Eyepiece Solar Filters.Some older telescopes came with â€œeyepiece solar filtersâ€� like this one. Do me a favor,if your old telescope came with one of these THROW IT OUT. They are not safe, they havecracked and subsequently allowed unfiltered sunlight to reach eyepieces, and if your eyeis there at the time, it can definitely cause blindness.Because solar filters can be expensive, there are ways to MAKE a solar filter â€“ like thisone. Baader or Thousand Oaks Optical both sell solar filter film for a reasonable pricethat can be made into a simple solar filter.
I have links on â€œeyes on the sky dot comâ€�that show you how to make your own filter for less than a retail version. One thingto be careful of is do NOT use â€œphotographicâ€� solar filter film for visual use â€“ it letsin too much light and can damage your eyes. Also, those two companies or any filter byMeade, Celestron or Orion telescope should be just fine. A couple more things to remember:Use common sense â€“ if the filter you are using hurts your eyes, STOP looking â€“ butnote that damage may be done to your eyes with unsafe methods that do not cause painto your eyes too. That is why it is important to ONLY use safe methods. It is not safe tolook at the sun even at sunset when it is
What are those floaty things in your eye Michael Mauser
Have you ever noticed something swimmingin your field of visioné It may look like a tiny wormor a transparent blob, and whenever you try to geta closer look, it disappears, only to reappearas soon as you shift your glance. But don't go rinsing out your eyes! What you are seeing is a common phenomenon known as a floater. The scientific name for these objectsis Muscae volitantes,
Latin for quot;flying flies,quot; and true to their name,they can be somewhat annoying. But they're not actually bugsor any kind of external objects at all. Rather, they exist inside your eyeball. Floaters may seem to be alive,since they move and change shape, but they are not alive. Floaters are tiny objectsthat cast shadows on the retina, the lightsensitive tissueat the back of your eye.
They might be bits of tissue, red blood cells, or clumps of protein. And because they're suspendedwithin the vitreous humor, the gellike liquidthat fills the inside of your eye, floaters drift alongwith your eye movements, and seem to bounce a littlewhen your eye stops. Floaters may be onlybarely distinguishable most of the time.
They become more visiblethe closer they are to the retina, just as holding your hand closerto a table with an overhead light will result in a moresharply defined shadow. And floaters are particularly noticeable when you are lookingat a uniform bright surface, like a blank computer screen, snow, or a clear sky,
where the consistency of the backgroundmakes them easier to distinguish. The brighter the light is,the more your pupil contracts. This has an effect similarto replacing a large diffuse light fixture with a single overhead light bulb, which also makesthe shadow appear clearer. There is another visual phenomenonthat looks similar to floaters but is in fact unrelated. If you've seen tiny dots of lightdarting about
when looking at a bright blue sky, you've experienced what is knownas the blue field entoptic phenomenon. In some ways,this is the opposite of seeing floaters. Here, you are not seeing shadows but little moving windowsletting light through to your retina. The windows are actually causedby white blood cells moving through the capillariesalong your retina's surface. These leukocytes can be so largethat they nearly fill a capillary