# Is there a reason I'm having problems finding the Pinwheel Galaxy

**URL:** <https://boards.straightdope.com/t/is-there-a-reason-im-having-problems-finding-the-pinwheel-galaxy/794190>\
**Category:** Factual Questions\
**Created:** [August 20, 2017, 3:00pm UTC](https://boards.straightdope.com/t/is-there-a-reason-im-having-problems-finding-the-pinwheel-galaxy/794190 "2017-08-20T15:00:40Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![D18](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@D18](https://boards.straightdope.com/u/D18)\
**Post date:** [August 20, 2017, 3:00pm UTC](https://boards.straightdope.com/t/is-there-a-reason-im-having-problems-finding-the-pinwheel-galaxy/794190/1 "2017-08-20T15:00:40Z")

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At the cottage, so I have my annual period of dark skies for some backyard astronomy. 🆒

I’m not a bad star-hopper, and have no issue finding, say, Andromeda, Bode’s or the Cigar Galaxy. I’m damned if I can find the Pinwheel Galaxy, though. I’m not clear on why that might be - it’s magnitude is between that of Bode’s and the Cigar, and it’s location looks to be pretty straightforward - roughly an equilateral triangle with the last two stars of the handle of the Big Dipper. Suggestions?

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**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\
**Post date:** [August 20, 2017, 3:17pm UTC](https://boards.straightdope.com/t/is-there-a-reason-im-having-problems-finding-the-pinwheel-galaxy/794190/2 "2017-08-20T15:17:59Z")

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It’s simple - it has very low surface brightness. The magnitude measures _total_ brightness. M101 is larger than M81 or M82, so the light is spread out over a larger area. I’ve only seen M101 under very dark skies (using large binoculars), while I can see M81 and M82 from my front yard.

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**Author:** ![D18](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@D18](https://boards.straightdope.com/u/D18)\
**Post date:** [August 20, 2017, 3:42pm UTC](https://boards.straightdope.com/t/is-there-a-reason-im-having-problems-finding-the-pinwheel-galaxy/794190/3 "2017-08-20T15:42:23Z")

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Ah. Thank you! So would I be better off with a pair of binoculars than my 4" telescope?

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**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\
**Post date:** [August 20, 2017, 4:22pm UTC](https://boards.straightdope.com/t/is-there-a-reason-im-having-problems-finding-the-pinwheel-galaxy/794190/4 "2017-08-20T16:22:51Z")

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M101 should be visible in a 4" telescope M101 _if_ the sky is sufficiently dark, and magnification is low enough. I’d aim for exit pupil of 5~7mm; for 4" aperture, that would be 14x to 20x magnification.

Given the same aperture and magnification, two eyes are better than one. But if you compare binoculars to a larger aperture telescope, it’s hard to say. If it’s a choice between 11x80 binoculars and an 8" Dobsonian, for example, I think the Dob wins easily. 11x80 binos vs. 4" refractor might be close.