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Post by Vypernight on Jun 1, 2009 5:13:00 GMT -5
This is probably boring to those used to seeing clusters of lesser-known stars, but this was really cool to me.
My friend and I were walking around outside one night when we ran into our neighbor. We talked for a bit before he offered to bring his telescope over. This thing was huge, to the point where he could barely lift it (If I'd known that, I would've offered to help).
Anyways, he pointed it at the moon, and every feature came out so clear it was absolutely beautiful. We looked at some stars as well, but the moon was the part I remember the most.
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Post by Star Cluster on Jun 1, 2009 6:32:49 GMT -5
This is probably boring to those used to seeing clusters of lesser-known stars, but this was really cool to me. My friend and I were walking around outside one night when we ran into our neighbor. We talked for a bit before he offered to bring his telescope over. This thing was huge, to the point where he could barely lift it (If I'd known that, I would've offered to help). Anyways, he pointed it at the moon, and every feature came out so clear it was absolutely beautiful. We looked at some stars as well, but the moon was the part I remember the most. The moon is indeed beautiful to view through a telescope. As you said, the detail is incredible and almost unbelievable, even through a small telescope. The best time to view the moon is when it is about mid-phase or less, either waxing or waning. Regardless of when you view it, a lunar filter is a must. The reflecting sunlight is just too intense for your eye if viewed without one, especially with a higher powered 'scope like the one you describe. At full moon, you'll see spots after viewing even with a filter. Besides that, the angle of sunlight hitting the moon during the lesser phases creates shadows in the craters and the mountains that gives a more detailed and perspective view. Even a pair of binoculars will give you an idea of the detail on the moon. But I don't recommend and even discourage you from viewing the moon with them even close to a full moon due to the intensity of the reflected sunlight.
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starbrewer
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Post by starbrewer on Jun 13, 2009 5:05:58 GMT -5
Magnification is F(obj) / F(eye); where F(obj) is the focal length of the objective lens or curved mirror, and F(eye) is the focal length of the eyepiece. My scope: the curved mirror has a focal length of 1200 mm, with the 25 mm eyepiece, 1200/25 = 48x. If a Barlow is used, multiply the final number by the magnification factor of the barlow. If I use the 25 mm eyepiece and a 2x barlow, that gives me a magnification of 96x.
Exit pupil is the "hole of light" in the eyepiece, equal to the aperture divided by the magnification. My scope has an aperture of 200 mm, so at 48x, the exit pupil is 4.17 mm. Avoid an exit pupil of less than 0.5 mm (see highest useful magnification, previous post), the image becomes fuzzy and lacks detail; you've exceded the resolution of the human eye.
Focal ratio is the aperture divided by the focal length of the objective. My scope, aperture is 200 mm, F(obj) = 1200 mm, so the focal ratio is "f/6". Slower scopes (f/x, where x=>6) are easier to collimate, and there is less curvature and distortion in the image. If you have a fast scope (f/x, where x<=4) you may consider using a barlow, which extends the focal length and slows the focal speed. Something called "Para-Cors" are sometimes used, which are really just weak barlows.
Now that I've used the word "barlow" so much, I think I should tell you what it is. It is a divergent, or minus power lens, which is used to step up magnification. With a focused cone of light, instead of completely diverging the light, it still focuses but at a sharper angle and, effectively, a longer focal length.
FOV, field of view. True field of view is apparent field of view (a specification that varies with each individual eyepiece) divided by magnification. Example: my scope with 25 mm Sirius Plossl eyepiece, whose apparent field of view is 52°, magnification 48x, gives a true field of view at 65 minutes, or 1 degree and 5 minutes, or roughly twice the width of the full moon.
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starbrewer
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Post by starbrewer on Jun 13, 2009 7:02:00 GMT -5
Must-Add to list of favorites: M42, the Orion Nebula, found in Orion's sword. Only the moon contains more detail! 5 stars out of 4.
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starbrewer
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Post by starbrewer on Jul 20, 2009 6:00:59 GMT -5
Tonight I was out again, some cirroform clouds rolled in, but decided instead of going home right then and there, rather to just wait it out. Normally when clouds appear, more come. The Milky Way returned. My big catch after that was NGC 7331, an edge-on galaxy in Pegasus.
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Post by Jedi Knight on Jul 20, 2009 7:12:18 GMT -5
And since Pluto's "moon" Cheron is almost the same size as Pluto itself, and they actually orbit a spot located in the space between them, the reclassification of Pluto just made more sense. Don't the Earth and the Moon orbit a spot in the space between them, too?
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Post by Star Cluster on Jul 20, 2009 8:27:08 GMT -5
And since Pluto's "moon" Cheron is almost the same size as Pluto itself, and they actually orbit a spot located in the space between them, the reclassification of Pluto just made more sense. Don't the Earth and the Moon orbit a spot in the space between them, too? No, not at all. While the gravitational pull of the moon does create a "wobble" in the earth's rotation, the orbital center is still contained inside the sphere of the earth, just not the dead center of the planet. Since the moon is so much smaller than the earth, its pull is not great enough to pull the earth entirely off center. The orbital center of the Pluto/Cheron combination is a point located outside of both bodies. Since Cheron is only proportionally slightly smaller than Pluto, the pull on each body by the other is enough that they pull each other off center and spin around a point between them centered just slightly toward Pluto.
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Post by Jedi Knight on Jul 20, 2009 9:15:03 GMT -5
Thanks! That makes sense.
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starbrewer
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Post by starbrewer on Jul 20, 2009 9:20:26 GMT -5
Pluto and Charon are tidally locked to each other. The tidal locking between earth and moon is one-way: the moon is tidally locked to earth, but the earth is not tidally locked to the moon.
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Post by Jedi Knight on Jul 20, 2009 10:13:27 GMT -5
Pluto and Charon are tidally locked to each other. The tidal locking between earth and moon is one-way: the moon is tidally locked to earth, but the earth is not tidally locked to the moon. I like this one. Not only is it a good point, when it comes to the earth/moon relation it is possible to observe even for the layman.
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starbrewer
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Post by starbrewer on Jul 22, 2009 7:00:42 GMT -5
tidal locking causes a body, like a moon, to always show the same side to another.
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John Gospel
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Post by John Gospel on Jul 22, 2009 20:28:31 GMT -5
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starbrewer
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Post by starbrewer on Jul 23, 2009 6:28:53 GMT -5
john Gospel: is that a demonstration of tidal locking, or a demonstration that Rule 34 applies to galaxies?
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Post by starbrewer on Aug 15, 2009 12:59:13 GMT -5
WR 104 Betelgeuse (Alpha Orionis) Rigel (Beta Orionis) Antares (Alpha Scorpii) Eta Carinae
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Post by malendras on Aug 16, 2009 2:53:57 GMT -5
I'd absolutely love to get myself a telescope. Just two problems - money, and I live in New York City. We have some of the worst light pollution in the world. I'm not sure how much I'd see from here.
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