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FoggyEyes
sage


Reged: 06/01/13

Loc: Columbus, Ohio
Counting the stars in the Pleiades
      #6104699 - 09/27/13 06:15 PM

LP where I live is terrible, but is clearly better in the morning. At around 6:00 I think that I can count five or six stars in the Pleiades with just my eyes (well, and glasses). Sound about right?

And, by the way, my eyes aren't very young and my vision prescription is about due to be updated.


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Tony Flanders
Postmaster
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Reged: 05/18/06

Loc: Cambridge, MA, USA
Re: Counting the stars in the Pleiades new [Re: FoggyEyes]
      #6105354 - 09/28/13 06:32 AM

Quote:

LP where I live is terrible, but is clearly better in the morning. At around 6:00 I think that I can count five or six stars in the Pleiades with just my eyes (well, and glasses). Sound about right?




Yes, most people can see 5 or 6 stars in the Pleiades. It probably depends more on your eyesight than on the level of light pollution. Six Pleiads are brighter than magnitude 4.5, a typical limit for a very bright city sky.


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BrooksObs
professor emeritus


Reged: 12/08/12

Re: Counting the stars in the Pleiades new [Re: Tony Flanders]
      #6105356 - 09/28/13 06:41 AM

Yes, light pollution severely impacts what one sees in the way of stars in the Pleiades most places these days.

When I first move to my (then) rural home 40 years ago, on the best late autumn and winter nights I could count 14 stars in the group. Nowadays, with the light pollution situation growing ever worse by the year, I usually only manage 6.

BrooksObs


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SporQ
member


Reged: 09/03/13

Loc: Indiana, USA
Re: Counting the stars in the Pleiades new [Re: BrooksObs]
      #6105474 - 09/28/13 08:31 AM

You see six stars because the seventh sister is hiding. I believe that is how the myth goes.

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Seldom
professor emeritus


Reged: 08/05/12

Loc: N of Cedar City Light Dome
Re: Counting the stars in the Pleiades new [Re: SporQ]
      #6105703 - 09/28/13 10:56 AM

Wikipedia says Subaru (Japanese for Pleiades) means "unite". Is that the Japanese astronomical equivalent of "cluster?"

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rnc39560
Pooh-Bah
*****

Reged: 07/23/13

Loc: MS coast
Re: Counting the stars in the Pleiades new [Re: Seldom]
      #6106119 - 09/28/13 02:58 PM

wow.... I don't really have BAD LP, and I only see a smudge of light with a couple bright dots! With my glasses!

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Seldom
professor emeritus


Reged: 08/05/12

Loc: N of Cedar City Light Dome
Re: Counting the stars in the Pleiades new [Re: rnc39560]
      #6106137 - 09/28/13 03:05 PM

Quote:

wow.... I don't really have BAD LP, and I only see a smudge of light with a couple bright dots! With my glasses!




Depends on how high they are. I looked at them last evening around 11:00 MDT, and they were a blur. When they culminate I can count 5 or 6. The OP was counting at 6:00 AM, just after culmination. Back in PA I saw the Pleiades from a clearing in tall trees. I was living in an orange zone, and could count at least 5 through my neighbor's security light glare. When I moved to UT, all I could see was a blur despite blue zone sky. Of course I was seeing them a lot closer to the horizon. Later in the year, when the Pleiades culminated before my bedtime I realized that the reason they looked so good in PA was that I could only see them when they were really high.

Edited by Seldom (09/28/13 03:14 PM)


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Feidb
Pooh-Bah


Reged: 10/09/09

Loc: Nevada
Re: Counting the stars in the Pleiades new [Re: Seldom]
      #6106352 - 09/28/13 05:30 PM

It is known as the Seven Sisters, so seven is the magic number. However, the cluster is known to have over a thousand members so those seven are only the most recognizable members. Even in a large telescope, you'll never see anywhere near a thousand stars. Be happy with six or seven.

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mogur
scholastic sledgehammer
*****

Reged: 07/29/11

Loc: WI
Re: Counting the stars in the Pleiades new [Re: Feidb]
      #6106491 - 09/28/13 07:28 PM

As I understand it the seventh sister was little Alcore. which deserted the group to pair up with Mizar. They remain together today. A cute story if nothing else!

BTW, I can see a couple dozen with a good 3 degree FoV.


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SteveNH
professor emeritus
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Reged: 07/10/11

Loc: Millbrae, CA
Re: Counting the stars in the Pleiades new [Re: Seldom]
      #6106513 - 09/28/13 07:51 PM

Quote:

Wikipedia says Subaru (Japanese for Pleiades) means "unite". Is that the Japanese astronomical equivalent of "cluster?"


In Japanese, the suffix "-dan" is the word used in astronomy to refer to a group or a gathering of stars; so in Japanese, the word for star cluster is "seidan" where "sei-" is the reading for the word "star" (pronounced like "SAY DONE").

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Kraus
Pooh-Bah


Reged: 03/10/12

Loc: Georgia.
Re: Counting the stars in the Pleiades new [Re: SteveNH]
      #6106754 - 09/28/13 11:24 PM

The seven daughters are right fun in the telescope. See how much nebulosity you can detect around the bright members. You might mistake it for fog on the eyepiece from your breath.

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Widespread
professor emeritus


Reged: 05/11/11

Loc: Bowling Green, Kentucky
Re: Counting the stars in the Pleiades new [Re: SteveNH]
      #6106797 - 09/29/13 12:06 AM

Quote:

Quote:

Wikipedia says Subaru (Japanese for Pleiades) means "unite". Is that the Japanese astronomical equivalent of "cluster?"


In Japanese, the suffix "-dan" is the word used in astronomy to refer to a group or a gathering of stars; so in Japanese, the word for star cluster is "seidan" where "sei-" is the reading for the word "star" (pronounced like "SAY DONE").




The use of the term Subaru for the Pleiades apparently goes back to the mists of history (or the Nara Era, which is close enough).
It is thought to come from an (archaic) reading of a commonly used contemporary kanji which does indeed mean "to unite".

From what little I have seen, Japanese astronomical nomenclature seems likely to have been translated from other languages. Globs are kyujo seidan (Cue Joe, Say Don, lit. "Spherical star group"), OCs are sankai seidan (Son Kai, Say Don, lit. " Scattered open star group").

Best,
David


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Astrodj
professor emeritus
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Reged: 08/24/11

Loc: Missouri
Re: Counting the stars in the Pleiades new [Re: BrooksObs]
      #6106834 - 09/29/13 01:07 AM

Quote:

Yes, light pollution severely impacts what one sees in the way of stars in the Pleiades most places these days.

When I first move to my (then) rural home 40 years ago, on the best late autumn and winter nights I could count 14 stars in the group. Nowadays, with the light pollution situation growing ever worse by the year, I usually only manage 6.

BrooksObs




That beats me. The best I ever managed when my eyesight was still in it's prime from a good dark site was 12 for sure, 13 a definite maybe. And I had really good eyesight compared to most. I miss those days!

Now I'm down to six from my red zone backyard, but I can still get 7 from a yellow or green zone.


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Tony Flanders
Postmaster
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Reged: 05/18/06

Loc: Cambridge, MA, USA
Re: Counting the stars in the Pleiades new [Re: Astrodj]
      #6107132 - 09/29/13 09:58 AM

Quote:

That beats me. The best I ever managed when my eyesight was still in it's prime from a good dark site was 12 for sure, 13 a definite maybe. And I had really good eyesight compared to most. I miss those days!

Now I'm down to six from my red zone backyard, but I can still get 7 from a yellow or green zone.




I doubt that most people could see more than 10 even in pristine skies.

The Pleiades are a particularly poor test for light pollution because they confuse two issues: seeing faint stars, and separating faint stars from the glow of much brighter stars nearby.

It's similar to seeing Jupiter's moons. All four Galilean moons are well above the limiting magnitude for a decent suburban sky, yet hardly anybody can see them naked-eye because they're obscured by the glare of Jupiter.

Likewise, the star 22 Tau is magnitude 6.4, which would normally be quite easy in a dark sky. But it's jut 2.5 arcminutes from much brighter 21 Tau. And both of those, in turn, are quite close to vastly brighter 19 and 20 Tau.

Given all those circumstances, it would indeed be a remarkable feat to see 22 Tau even in pristine skies. No doubt possible for a few people, but not for most.

The number of stars in the Pleiades also depends how far you're willing to go from the bright dipper formation. It's a very rich part of the sky, and in fact true cluster members of the Hyades are interspersed in the sky with true cluster members of the more distant Pleiades.

Incidentally, seeing 7 stars in the Pleaides is a bit exotic. I think people are more likely to see either 6 or 8, since the visibility of 16 Tau and 28 Tau (the 7th and 8th brightest stars) is quite similar.

Edited by Tony Flanders (09/29/13 10:01 AM)


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MikeBOKC
Post Laureate
*****

Reged: 05/10/10

Loc: Oklahoma City, OK
Re: Counting the stars in the Pleiades new [Re: FoggyEyes]
      #6107650 - 09/29/13 02:38 PM

The fascinating thing about M45 to me is not the number of stars I can see but the fact that this is a slowly dispersing cluster of recently formed stars that is one step along the continuum of stellar evolution exhibited by the Orion nebula. Most of the bright young stars in M45 are less that 100 million years old and they are slowly moving apart from their birth site, through some remaining interstellar gas. Plus when you look at M45 you can see what our own stellar neighborhood probably looked like about 4 billion years ago.

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Gert K A
sage


Reged: 07/16/12

Loc: Copenhagen, Denmark
Re: Counting the stars in the Pleiades new [Re: MikeBOKC]
      #6107992 - 09/29/13 06:28 PM

Quote:

-Mike

The fascinating thing about M45 to me is not the number of stars I can see but the fact that this is a slowly dispersing cluster of recently formed stars that is one step along the continuum of stellar evolution exhibited by the Orion nebula. Most of the bright young stars in M45 are less that 100 million years old and they are slowly moving apart from their birth site, through some remaining interstellar gas. Plus when you look at M45 you can see what our own stellar neighborhood probably looked like about 4 billion years ago.




That... and also that they are very very pretty!


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Thorkill
member


Reged: 04/16/13

Loc: Troms, Norway
Re: Counting the stars in the Pleiades new [Re: Gert K A]
      #6108016 - 09/29/13 06:57 PM

Tony interesting post. I see 6 at all times(With glasses) but the 7th and 8th keep showing emself if i work With side vision, but i dont see all 8 at once.

Edited by Thorkill (09/29/13 06:58 PM)


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rnc39560
Pooh-Bah
*****

Reged: 07/23/13

Loc: MS coast
Re: Counting the stars in the Pleiades new [Re: Thorkill]
      #6108078 - 09/29/13 07:41 PM

Ok! I went out EARLY morning, around 4:00 am. I could make out six. WITH my glasses...

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Lamb0
Carpal Tunnel
*****

Reged: 07/25/07

Loc: South Eastern(ish) Nebraska
Re: Counting the stars in the Pleiades new [Re: Tony Flanders]
      #6108484 - 09/30/13 12:15 AM

Quote:

I doubt that most people could see more than 10 even in pristine skies.

It's similar to seeing Jupiter's moons. All four Galilean moons are well above the limiting magnitude for a decent suburban sky, yet hardly anybody can see them naked-eye because they're obscured by the glare of Jupiter.

Incidentally, seeing 7 stars in the Pleiades is a bit exotic. I think people are more likely to see either 6 or 8, since the visibility of 16 Tau and 28 Tau (the 7th and 8th brightest stars) is quite similar.




You just need darker skies and younger eyes!

Twelve to fourteen Pleiades is NOT uncommon with younger (or very well preserved) eyes with adapted vision at a moderately dark site... YMWV

All four Galilean moons are well above the limiting magnitude for a decent suburban sky as I consistently proved in college through my dorm room window (sans screen). Again, younger eyes are a boon although the separation should be near it's widest. Two are easy, the third is more difficult, but all four together are a visual challenge most youth and many adults (perhaps visually corrected) can achieve so long as they don't "know" it's impossible.

Methodology (for verification) is part of it; but utilizing averted vision and other techniques takes practice (preferably learned from a mentor) for best results. Discriminating closely spaced point sources of light also requires practice under decent conditions. Start with Mizar & Alcor and other easy "doubles" when the Galilean satellites are not in view... it does get easier if your vision is up to it; and don't forget to challenge the younger set even if the gr'ups can't see them all unassisted.


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Tony Flanders
Postmaster
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Reged: 05/18/06

Loc: Cambridge, MA, USA
Re: Counting the stars in the Pleiades new [Re: Lamb0]
      #6108754 - 09/30/13 07:17 AM

Quote:

Twelve to fourteen Pleiades is NOT uncommon with younger (or very well preserved) eyes with adapted vision at a moderately dark site... YMWV




Do you have statistics to back that up?

Quote:

All four Galilean moons are well above the limiting magnitude for a decent suburban sky




Of course they are -- as I said. But that doesn't mean that people can actually see them. The obstacle is Jupiter, not light pollution.

Quote:

As I consistently proved in college through my dorm room window (sans screen). ... Two are easy, the third is more difficult, but all four together are a visual challenge most youth and many adults can achieve ...




Are you claiming to have seen all four Galilean moons simultaneously without optical aid? I have never heard anybody claim to do that before. It is certainly far beyond the ability of any normal person.

It is, of course, a matter of record that nobody described seeing any moons of Jupiter before the invention of the telescope.


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