Comments on: The stars are shining tonight

Question: The stars are shining tonight

megatherium — Tue, 11 Sep 2012 13:48:07 -0800

When you look up on a starry night, you see more than a thousand points of light. How many of what we see with the naked eye are stars and how many are galaxies?

By: plep

plep — Tue, 11 Sep 2012 13:50:43 -0800

Apart from the Milky Way, only the Magellanic Clouds (in the southern hemisphere) and Andromeda Galaxy can be seen with the naked eye. http://curious.astro.cornell.edu/question.php?number=590

By: Kid Charlemagne

Kid Charlemagne — Tue, 11 Sep 2012 14:14:47 -0800

It should also be noted, the Andromeda Galaxy is 5° across and is not a little point of light, but rather a huge and very faint smudge.

By: yoink

yoink — Tue, 11 Sep 2012 14:30:58 -0800

Wikipedia has a slightly longer list of galaxies that can be seen with the naked eye.

By: Scientist

Scientist — Tue, 11 Sep 2012 14:46:16 -0800

You can also see the odd nebula and star cluster if you know where to look, plus five of the planets (and the moon, naturally).

By: Chocolate Pickle

Chocolate Pickle — Tue, 11 Sep 2012 15:05:03 -0800

If you're in a city, or any place with significant light pollution, you can't see any galaxies at all.

By: Chocolate Pickle

Chocolate Pickle — Tue, 11 Sep 2012 15:11:08 -0800

Quite a few of the Messier objects turn out to be galaxies. When Messier was creating his list of "things in the sky visible to the naked eye which are not comets", he was working without a telescope. Some of the Messier galaxies are quite spectacular e.g. M101.

By: elendil71

elendil71 — Tue, 11 Sep 2012 15:46:45 -0800

It should also be noted, the Andromeda Galaxy is 5° across and is not a little point of light, but rather a huge and very faint smudge.

I used to do a fair bit of astrophotography back in the day. With a sidereal tracker (mine was home-made with two boards, a hinge and a 1/4" screw) and my Pentax 1000 I got some pretty nice shots over the years. Andromeda is surprisingly big across the sky. You just can't see it with the naked eye or without a long exposure.

Not sure how a common digital camera would measure up to accomplishing the same thing, but damn, that Pentax took some fine long exposure photos.

By: Betelgeuse

Betelgeuse — Tue, 11 Sep 2012 18:36:01 -0800

Assuming you're in the Northern Hemisphere, basically everything that's not a planet or our Moon is a star in the Milky Way. You can see the bulge of Andromeda as a faint smudge if you're in a place with little light pollution, but I'm fairly skeptical of the other northern hemisphere "naked eye galaxies" on the linked Wikipedia page. You'll notice that some of them are "one guy claims to have seen this."

If you're in the southern hemisphere, add the LMC, SMC, and Omega Cen (whether this last one is truly a galaxy is up for debate).

Messier used a telescope, so most Messier objects are not visible with the naked eye.

By: Sunburnt

Sunburnt — Wed, 12 Sep 2012 10:27:39 -0800

Assuming you have perfect seeing (not eyesight, but seeing, i.e. viewing conditions, as far as weather, ambient light, etc.) at sea level, the human eye should see all stars brighter than (apparent) magnitude +6. (brightness increases 10 times with every magnitude, but lower numbers = brighter-- the sun is a -26 magnitude for example, while +6 is very dim). Some sources say +6.5 or +7, but I don't know how that affects the below number, which I'm told correlates to +6.

That works out to about 6000 visible stars in the sky, or roughly 3000 visible in a given hemisphere in an instant.