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Re: (meteorobs) Solar filter
On Tue, 25 Feb 1997, Ron Rennie wrote:
> Hi all
> While the thread of the solar filters was going on the thought ocurred to me
> that through the binoculars at 15X with the solar filters attached, the sun
> actually looked smaller than its flaming orb looks to the naked eye, without
> magnification. I wondered how big it would look through the filter only
> and found that it looked quite small. Much smaller than you would think
> from seeing the blazing ball in the sky each day. After a little
> calculation I find that it's angular diameter is only 32 arc minutes.
> Quite surprising!
>
> Ron
Yes, our eyes seem to think that brighter objects are larger, in the
absence of any ability to compare. If the Sun were any larger in
apparent size, we wouldn't have solar eclipses! What's really weird are
faint deep-sky objects and telescopic views. At a dark site, I can see
the Andromeda galaxy as several degrees long, but without measuring I
would never guess that it is that large compared to the Moon's 0.5 degree
diameter. Also, Jupiter's disk subtends over 0.5 arcminutes, so if you
magnify it 60x, its apparent angular diameter is larger than the Moon
appears to the naked eye. But it LOOKS tiny!
--
Wes Stone <wstone@lclarkdot edu> Lewis and Clark College, Portland, OR
SKYTOUR Amateur Astronomy Hypertext:
http://www.lclarkdot edu/~wstone/skytour/skytour.html
References: