Question About Looking At The Sun?

Question

My grandson was wondering if the special lenses we use to look at our sun would work on suns that were in a different class -- ie A white sun or a red giant? Anyone here know if we would need a different type of lens to look at Betelguse -- if we were there? (Forgive me if I spelled it wrong. I'm not an astronomer. lol, obviously.)

Answer 1

My full aperture solar filter for my telescope lets one photon through for each 100,000 attempts.  You'd normally call it opaque. But that's all it does.  You can't see any other stars in it, because they aren't bright enough.  The Sun is a star, but very close, and therefore bright.

Other stars, red giants, blue, etc., do not require filters, because they're so far away.  Betelgeuse will not blind you when looked at from the Earth.

Now if you were in Betelgeuse orbit, you might very well need a solar filter, depending on how close you were.  You might even want a hydrogen alpha solar scope so that you could see lots of interesting detail.  These have come down in price.  My club has one.  I personally don't have $1000 to spend on a telescope that only allows me to see one object.



Going to Betelgeuse seems like the hard way to do it.  It takes a long time to get there.  The Hubble Space Telescope, and possibly others, have imaged the surface of Betelgeuse, even revealing Sun spots.

Answer 2

DONT DO IT !!!!!!!!!!!!!!!  It can make you blind in just a few seconds. I don't know the official time but do not look at the sun. Tell him to look at a lightbulb. That's what it looks like.

Answer 3

The films we currently use to look at OUR star - Sol - would not work at a white dwarf or a red giant - in the first case, it would not block enough of the UV, and in the latter case, not block enough of the infrared.

HOWEVER, the standard fall-back pinhole box works for either. (Provided you have enough sunscreen - like SPF 3000...

Hope this helps.

Answer 4

That's a good question. Astronomers would know. They probably never thought of what filter it would take to look at say Betelgeuse or Antares. It would be what different stars emits at that close a distance. Gama rays, stronger ultra violet rays, X-trays, etc. However a sun filter for viewing would work on all if they were far or close enough to be the same size as the sun in the sky. You would have to have different shades of filters for different intensity stars. Some stars are hundreds of times brighter than the sun, even though they are the same size as the sun.

Answer 5

It would depend entirely on the star's individual luminosity, but any light that we get here at earth is so faint that you can look at it all you want from the earth without harm.  since intensity changes with the square if the distance (aka, it would be trillionths, if that much, of the original intensity of the star).

Answer 6

That's a really interesting question.

I assume what you mean is, if we were on a planet with a different type of star, then how would that change how we would design a filter to look at it.

There are two things...

1) Sheer luminosity need to be dealt with - so as suitti said - having a filter that simply absorbs most of the photons would be necessary. From that point of view - the filter you have would be adequate. Actually welders goggles are good enough.

2) If we evolved with a different star, our eyes' sensitivity would be different. We are sensitive to visible light becuase that's what is most useful to us.

Also - from the ground, most of the UV all the Xray and gamma rays are filtered out for us by the atmosphere, as is much of the infrared.

So even tho a red star would have less UV and more infrared; or a white star would have more UV and (relatively) less infrared, chance are we'd still be most sensitive to visible light and so your regular solar filter would work just fine...