Talk:Apparent magnitude/Archive 1

Suggestions

Formulas! We should include formulas here and in absolute magnitude.--AN

The 1st paragraph for this page gets confusing rather quickly. Would it be possible for someone with knowledge of the subject to clarify the definition before jumping into numerical examples?

The current definition seems to be fine but the first paragraph was needlessly complex to be sure. I took out the, imo, unneeded part and left it at that, brief. I also took the liberty of pulling the sections regarding the history of the system up to just after the introductory sentences since that seemed more logical to me. I anyone has a problem with that please discuss it here. I'm sure the article could use more tweaking and maybe someone can do that or I'll come back to it later. --Kalsermar 23:14, 6 October 2005 (UTC)[reply]

Magnitude (astronomy)

When amateurs refer to magnitude in astronomy, they probably don't know the difference between apparent magnitude and absolute magnitude. This also creates a problem for the disambigation link repair: I, for example, have no idea whether to pipe magnitude link from (exampple) All Sky Automated Survey article to absolute or apparent. Could sb create the article in the heading explaining the basic magnitude idea in astronomy and comparing the specific types, so the current two articles would become subarticles? Note that currently it is a redirect to magnitude disambig - far from a pefect solution.--Piotr Konieczny aka Prokonsul Piotrus ^Talk 17:47, 9 January 2006 (UTC)[reply]

I changed Magnitude (astronomy) to a disambiguation page with short descriptions for the two types of magnitudes. Hopefully they make disambiguating little easier. I don't think that absolute magnitude is mentioned in many articles compared to apparent magnitude. For example, when the article says "limiting magnitude is n", "stars brighter than n magnitude" or "nth magnitude star", magnitude always refers to the apparent magnitude.--Jyril 23:21, 9 January 2006 (UTC)[reply]

So what is the standard?

Maybe I missed it, but I cannot find the modern reference point from which all other magnitudes are determined. I see that Vega used to be defined as zero, but not what the new standard is.

- me neither. Article doesn't explain either the Zero or any reason for the step size. I assume there is one?

Apparent magnitude of nebulous objects

I miss information on how the apparent magnitude of dim objects (galaxies, nebulae) is calculated, and how that is related to their visibility. Is the Triangulum Galaxy equally visible on the night sky as a star with the same magnitude? Apus 09:00, 25 October 2006 (UTC)[reply]

Bad editions

I see, that some information were lost during editions (for example interwiki). Someone should check the history carefully. 83.14.10.10 15:31, 31 October 2006 (UTC)[reply]

B or V for apparent magnitude.

In Talk:Andromeda_Galaxy#Apparent_magnitude the suggestion has been made "In general, it is much easier to find B magnitudes than it is to find V magnitudes, so B magnitudes are generally used in the infoboxes. However, the infoboxes are set up with "(V)" hardwired into them. It might be better just to set up the infoboxes so that the wave band may be specified in the inserted text rather than in the template".

However, this article says "The V band was chosen for spectral purposes and gives magnitudes closely corresponding to those seen by the light-adapted human eye, and when an apparent magnitude is given without any further qualification, it is usually the V magnitude that is meant, more or less the same as visual magnitude". Is there a good resolution for this? I have also posted on Template:Infobox Galaxy. Thincat 10:19, 6 June 2007 (UTC)[reply]

Apparent Magnitude means 'as it appears to the eye', so V magnitude should be the preferred magnitude band for this article. —Preceding unsigned comment added by 81.155.116.122 (talk) 14:37, 28 June 2008 (UTC)[reply]

We know that the V band is usually given to represent the visual magnitude. However the other bands should have a slight effect on this, particularly the B and R bands. Is there a way to quantify this? For example during a deep lunar eclipse the moon has a pronounced red color and simply assigning the V (green) magnitude would underestimate how bright the moon appears to the naked eye. — Preceding unsigned comment added by 137.75.201.73 (talk) 21:55, 12 October 2015 (UTC)[reply]

There are some references about variable star measurements that try to quantify this. However the amount of correction between V magnitude and apparent magnitude is somewhat elusive, when looking at data from measurements of stars having various values of color index. The totally eclipsed moon is another interesting challenge, with its mix of red and other colors. With a deep and red total eclipse, the correction can actually go either way. This is because the B-V and V-R magnitude differences are about the same, yet blue light may be more important for the eye's sensitivity at night.— Preceding unsigned comment added by 174.16.67.8 (talk) 15:52, 13 December 2015 (UTC)[reply]

Scale of Apparent Magnitude

Nearly one year ago, on October 29, 2006, the table titled Scale of Apparent Magnitude was deleted because the URL of the source could not be found. As of September 15, 2007, the table has been reinserted into the article, this time with a URL to Jim Kaler's THE 151 BRIGHTEST STARS. The fourth paragraph of Kaler's article provides at least some of the information and data shown in the table. I will personally search for additional sources (URLs) dealing with this exact subject and insert them onto the table. However, I perfectly welcome the contributions of other Wikipedia editers to the Scale of Apparent Magnitude data table, because I feel that this table would prove very beneficial to anyone curious about the various orders of magnitude and how they are distinguished from each other. --Richontaban 16:19, 15 September 2007 (UTC)[reply]

Consistency?

In some calculations on this page the value '2.5' is used. Other calculations use '2.512'. Shouldn't they at least be consistent? Dfmclean 18:17, 11 October 2007 (UTC)[reply]

The correct value is the (5th root of 100) = 2.511886432. But yes, humans like to round off for simplicity. 2.5^5 is only 97.65625. -- Kheider 20:57, 11 October 2007 (UTC)[reply]

-Actually, In Pogson's equation, 2.5 is 2.50000, an exact number from 5/2, not a round off of the number 2.512. The value 2.512 is found for the ratio of brightness between adjacent integer magnitudes. (i.e. It is the fifth root of 100). The 2.5 from Pogson's equation is thus completely different from 2.511886432...

Officially, yes, it is actually exactly 2.5. It is no longer the 5th root of 100, but was adjusted for ease of computation. Having irrational numbers in there just gets to be a pain... So 5 magnitudes is no longer exactly 100 times brighter (or dimmer). AstroDave (talk) 02:41, 19 November 2008 (UTC)[reply]

Apparently, there is no universal agreement. According to Sky and Telescope magazine ([1]): "One magnitude thus corresponds to a brightness difference of exactly the fifth root of 100, or very close to 2.512 — a value known as the Pogson ratio." ---Glenn L (talk) 04:26, 30 October 2009 (UTC)[reply]

AH! I have a thought to the source of this "confusion". The exponent/log formula between brightness and magnitude have a coefficient of 0.4 and reciprical 2.5, which is NOT the magnitude ratio, but a consequence of 100^(1/5)=10^(2/5), like
- m = m₀-2.5*log₁₀(B/B₀) = m₀ - 2.5*log₁₀(100) = m₀ -2.5*2 = m₀ - 5! (100 times brighter is 5 magnitudes lower)
- And the inverse, you'd NEVER calculate B=B₀*2.512^(m-m₀), but rather:
- B=B₀*100^((m₀-m)/5) or better B=B₀*10^((m₀-m)*0.4) = B₀*alog((m₀-m)*0.4)
Tom Ruen (talk) 06:02, 30 October 2009 (UTC)[reply]

Total integrated magnitude of the night sky

Hypothetically speaking, if the Sun was to suddenly wink out at this instant in time, the total isotropic radiation flux falling on the Earth's surface from the surrounding cosmic night sky would amount to -6.5 magnitudes. This quantity was first determined by Abdul Ahad (b. 1968-) and is generally known as Ahad's Constant [2]. 90.193.170.221 (talk) 14:35, 8 March 2008 (UTC)[reply]

This was featured in The sky this week for 23/10/2008 [3]. Ahad's constant will be a fixed quantity of starlight falling on the Earth's surface, but minute changes will happen to it as one travels many light years beyond the Solar System.

Do we know what this constant is expressed in candelas? Would there be a significant difference in the value if we applied a bolometric correction? Pomona17 (talk) 16:57, 10 September 2008 (UTC)[reply]

This would be meaningless for a single source of light (like a star), let alone an integrated magnitude constant of the sky. Bolometric correction for a whole sky brightness would cancel out to zero, since red stars would be offset by blue stars in their BCs.

That actually makes sense Pomona17 (talk) 14:14, 5 November 2008 (UTC)[reply]

Minimum brightness of Venus

The Table has an entry : "−3.7 Minimum brightness of Venus". Since Venus can transit the Sun, I would expect the minimum brightness to be substantially positive. It will then only be lit by the Earth and Moon and about half of the stars. -- 82.163.24.100

Actually some sunlight would make it through the outer edge of the atmosphere and be detectable. But most laymen do not stare at the sun while Venus (or Mercury) are transiting the disk. -- Kheider (talk) 00:06, 10 October 2008 (UTC)[reply]

Venus would have a different minimum brightness at every inferior conjunction, since its ecliptic latitude (and hence its elongation and phase angle) would all be different each time. For example at the inferior conjunction of 1999 Aug 20, the ecliptic latitude was -8° 07'; on 2001 March 30 it was +8° 01'; at the following inferior conjunction on 2002 Oct 31, it was -5° 42', and so on. Suntanman (talk) 18:15, 24 November 2008 (UTC)[reply]

To be rigorous and future-proof, the magnitudes given should be qualified by a mention of the observer's position. To Messenger, Sol must be nearer Mag 29. 82.163.24.100 (talk) 21:11, 9 October 2008 (UTC)[reply]

The opening line of this article says, "as seen by an observer on Earth". From Pluto, Venus would obviously be fainter (in apparent magnitude) than as seen from Earth. Perhaps you would enjoy studying absolute magnitudes more. -- Kheider (talk) 00:06, 10 October 2008 (UTC)[reply]

Venus is at its dimmest when it's transiting the Sun. But its brightness at that time is completely unmeasurable. So its minimum brightness would have to be calculated as the limit of measured brightnesses as it approaches the Sun. But what would that achieve? The minimum brightness of Venus is something that can never be observed. I suggest that this line is removed. Occultations (talk) 15:35, 28 February 2009 (UTC)[reply]

I have a tendency to disagree. The 2005 minimum brightest is calculated by NASA as around -3.8 when Venus is fully lit on the far side of the Sun. I don't know if removing this fact improves the table. When people look up at Venus in the night sky they will see it either approaching the far side of the Sun (dimmer) or the near side of the Sun (brighter). Venus has an orbit inclination of 3.39 degrees and seldom transits the disk of the Sun as seen from Earth. During these non-transits Venus can be easily observed with the SOHO telescope. For example, when Venus next passes between the Sun and Earth on 2009-Mar-28 around 02:00 UT it will be 0.2815AU from the Earth and have a Sun-Earth-Venus total separation angle of 8.1515 degrees. We don't currently list the moons minimum magnitude as it would appear during a solar or lunar eclipse because those are special cases. -- Kheider (talk) 16:35, 28 February 2009 (UTC)[reply]

Scale of Apparent Magnitude

Is this table really necessary? It appears just to show the reader how to round to the nearest integer. Even assuming that the reader doesn't know how to do this, none of the magnitudes reported in the article are actually reported rounded to the nearest integer, which would seem to make the table irrelevant to the article. Is there some reason for the inclusion of this that I am missing? —Jeremy (talk) 22:59, 25 November 2008 (UTC)[reply]

What would you be left with on that page if you remove the table? A mass of equations that has no meaning to the general astronomical community. The table gives meaning to the equations by pointing to relevant objects of specific brightnesses. So, yes, there is a strong logical basis for its inclusion. Suntanman (talk) 11:51, 3 December 2008 (UTC)[reply]

I'm not referring to the table of apparent magnitudes of known celestial objects. I'm referring to the scale table that I removed yesterday. You can see it in this revision. —Jeremy (talk) 14:44, 3 December 2008 (UTC)[reply]

Oh i thought were :-). Yes that other table was worth taking off. Good on you.Suntanman (talk) 17:44, 5 December 2008 (UTC)[reply]

Ahad's constant

I removed Ahad's constant from the table, since:

It is not the apparent magnitude of a known celestial object.

Yes, but consider the way Dave Oesper has positioned this in the magnitude scale in his article: "Brighter than Venus, but dimmer than the brightest Iridium satellite flares. "[4]. A total integrated magnitude number of -6.5 (Ahad's constant) sits between -8.0 (an Iridium satellite flare) and -6.0 (the Crab supernova); neither of those is for a celestial object that is permanently on view today. The Crab supernova as a matter of fact happened almost a thousand years earlier! Ahad's constant is a present day phenomenon and it makes perfect sense to include it in this table, as others seem to have discussed above on this very talk page.

It has not a significant coverage in peer-reviewed scientific articles in renowned journals, written by others than Ahad, and using the phrase Ahad's constant. In fact, there are none. Nor are there peer-reviewed scientific articles by Ahad on the subject.

The reference, which was given to justify Ahad's constant, links to a commercial web site also promoting and selling the works of fiction by Ahad. -- Crowsnest (talk) 01:11, 23 February 2009 (UTC)[reply]

Agreed about peer reviewed journals. But how many peer reviewed journals do you need to state that the Sun shines at magnitude -26.7? Or that the Full Moon shines at magnitude -12.6? These are self-evident facts, as is Ahad's constant. Also, the link [5] is to a scholarly written article page; not to the other page you mention about his book publicity, which was this one [6]Constructive editor (talk) 06:56, 23 February 2009 (UTC)[reply]

The apparent magnitude of the Sun and the Moon have been established long ago, and are referenced in many textbooks on the subject. Further these are celestial objects, the subject of the article.

"Ahad's constant" is a newly-proposed scientific number, and in science academic and peer-reviewed publications are required, see WP:RS#Scholarship. The term "Ahad's constant" would need a significant coverage in reliable secondary scientific sources, before being established as a well-known phrase, and its inclusion in this article not being of undue weight. I have not been able to find any such reference to "Ahad's constant". -- Crowsnest (talk) 13:19, 23 February 2009 (UTC)[reply]

It is very rare for scientific phonomna to be named after a SF author. The only case I can think of is Clarke orbit, which is rarely refered to as such, and normally refered to as geo-stationary (or similar). It seems to me that much of Ahad's constant (and other values) are self promotion, rather than notable science, and should not be included. I would guess that his concepts have previously been covered by authors, but not self promotoed in this way.
On a second note, Ahad's constant is an average value of light in the middle of interstellar space, all the other values are for objects as seen from the Earth, and as such Ahad's constant does not fit in with the list. Martin451 (talk) 14:08, 23 February 2009 (UTC)[reply]

This seems like a pretty obvious not-include unless it's a much more common term than the current choice of sources would suggest. -- BenRG (talk) 15:35, 23 February 2009 (UTC)[reply]

The articles affected have been changed according to the present consensus: "Ahad's constant" (and similar terms) are not notable as scientific astronomy topics, in the WP sense. "Abdul Ahad" is not a notable (or famous) astronomer according to the WP guidelines and policies.

Furthermore, from the deletion process at Wikipedia:Articles for deletion/Abdul Ahad it appears that (at this moment) Abdul Ahad is not notable enough to deserve an article at WP, neither as astronomer nor as SF writer. -- Crowsnest (talk) 22:38, 25 February 2009 (UTC)[reply]

Pluto, 1148 or 725 times fainter than naked-eye?

In the calculation for how much fainter Pluto is than naked-eye visibility, the value 6.0 is used, as in 2.512^{(13.65 - 6.0)} = 1148. The actual value for the "faintest stars observable with naked eye under perfect conditions" is given earlier as 6.5, which would make Pluto 2.512^{(13.65 - 6.5)} = 725 times fainter. So, is it 6.0 or 6.5? Zaardvark (talk) 16:18, 30 June 2009 (UTC)[reply]

Just depends on how you look at it. 6.0 is the generic limit quoted for most dark skies. But if you go up into the mountains (above some of the atmosphere) someone with great eyesight might see 6.5. So generically I would say at its brightest Pluto is about 1,000 fainter than naked eye visibility. But I also think it is important for people to know where the number is coming from. The naked eye limit and Pluto's apparent magnitude are not really fixed numbers. -- Kheider (talk) 21:38, 30 June 2009 (UTC)[reply]

That doesn't explain the discrepancy in the article, since there is no clear mention of such a 6.0 "normal limit" of the eyesight. The number should either be updated to 725 as Zaardvark says, or another "normal limit" of 6.0 should be added somewhere in the article. ... said: Rursus (^mbork³) 20:59, 16 November 2009 (UTC)[reply]

Updated. ... said: Rursus (^mbork³) 21:01, 16 November 2009 (UTC)[reply]

Drop-a-link

Here for the normal experience limiting magnitudes during various conditions. Practically available best conditions allow a normal vision normal experience viewer about 5.75 to 6.0, which fits better with my personal experience. ... said: Rursus (^mbork³) 21:41, 16 November 2009 (UTC)[reply]

Just depends on the source: I have seen claims of naked eye limits of 7.6 to 8.0. But "I" am just not comfortable claiming such obselete/extreme limits. But then again I wear glasses and was not born on Krypton. :) Here is a claim for the generic 6.0 that is often quoted. In 2007 I moved the wiki limit from 6.0 down to 6.5, but I just don't know how to put an exact value on almost subjective number. -- Kheider (talk) 23:28, 16 November 2009 (UTC)[reply]

The link above is from Inquinamento luminoso by Pierantonio Cinzano. It looks like some research org about light pollution. After some more digging: there seems to be an analysis by Bradley Schaefer from c:a 1990 mentioned in "Naked-eye star vis..." by Cinzano, Falchi and Elvidge, page 42, that defines a probability curve for naked eye limits as per observer. It seems there is a standard deviation of circa 1.0 in the direction towards faint, a few subjects exhibiting 1.5, while the deviation in the direction towards bright is much more fuzzy. I believe the number 6.0 is a statistical mean limiting magnitude, a "standard" observer under perfect conditions, while the limit 6.5 is a pretty good observer under perfect conditions. A very proficient observer under perfect conditions, would by the Cinzano, Falchi and Elvidge paper, demonstrate a faintness visibility improvement by maybe 1.3—1.5 mags, so the seemingly absurd magnitude measures given in Bortle Dark-Sky Scale (up to 8.0) seems to regard the few very proficient observers...

Sense morale: the naked eye limits (plural) is well defined and well treated in science, we can still pick and choose a value, f.ex. 6.5, but we must relate that value to a certain pretty well defined sky darkness, and certain pretty well defined observer proficiency. ... said: Rursus (^mbork³) 07:46, 17 November 2009 (UTC)[reply]

Bradley E. Schaefer's paper HERE!. It looks like a "classic" regarding eye limiting magnitudes in telescopes. Just remove the telescope and we have formulae for naked eye... ... said: Rursus (^mbork³) 08:04, 17 November 2009 (UTC)[reply]

Forget this last post: Schaefer explores limiting magnitudes in telescopes, it is Cinzano et al. that explores naked eye limiting magnitudes. Their measures are to be preferred. ... said: Rursus (^mbork³) 08:10, 17 November 2009 (UTC)[reply]

I was bold. I reverted limiting mag to 6.0, but then added a "trained naked eye amateur astronomer" at 7.0. ... said: Rursus (^mbork³) 08:20, 17 November 2009 (UTC)[reply]

I'm new here, but I'd like to suggest that a 6.0 is visible even at less than average dark sites, and is an indication of either eye defects or less than average conditions at a true dark site. As an astronomer, in my experience, observations in the high 7s require a lot of experience and perfect eyesight. However high 6 and low 7 observations at good sites do not require much beyond the cooperation of weather. M81, a galaxy of reported magnitude 6.9(and thus more difficult than the equivalent stellar magnitude), has been seen by people with the unaided eye, and while not easy, is not considered a gargantuan feat. A limiting magnitude of 6 suggests defective eyesight or light polluted skies. Unfortunatey the experience of most people is of spoiled, light polluted skies. If the intent of the list was to convey a liting magnitude of 6.0 for 'mean'people under moderately light polluted skies, then it would be justified. As I read it, however, I got the impression that beyond 6.0 is unfeasable for people except if they have superhuman eyesight and live on a mountain, and that's simply not true. —Preceding unsigned comment added by 80.235.35.162 (talk) 15:37, 27 November 2009 (UTC)[reply]

M81

The wiki article lists M81 at mag 7.89 and other sites list at as 6.9 as you mention. Do you have any idea why the difference? Is the extragalactic database listing the visual magnitude? -- Kheider (talk) 21:52, 27 November 2009 (UTC)[reply]

http://simbad.u-strasbg.fr/simbad/sim-id?Ident=M81 According to simbad, it seems one is a B mag, while the other is a V mag. The V mag should approximate visual better. That being said, since it's not a point source, a magnitude won't be a very good indicator of brightness, as that light is spread out, making it appear (both photographically and visually) as dimmer than it 'should'. —Preceding unsigned comment added by 80.235.35.162 (talk) 01:13, 28 November 2009 (UTC)[reply]

I have updated the v-mag for M33 from 6.3b to 5.7v to match SIMBAD. I was wondering if you could comment on the talk page at M81: Talk:Messier_81#Brightness_Discussion -- Kheider (talk) 10:57, 28 November 2009 (UTC)[reply]

Strange?

How can both of Hydra and Nix be Pluto's smallest moon (as in the list)? --87.93.30.46 (talk) 23:21, 6 June 2010 (UTC)[reply]

Someone had change the expression "Maximum brightness of Pluto's smallest moons Hydra and Nix" to list both values separately and they didn't bother to change the wording. -- Kheider (talk) 00:34, 7 June 2010 (UTC)[reply]

Jupiter 5000AU from the Sun

28 mag - Jupiter if it was located 5000AU from the Sun ([ref]Magnitude difference is 2.512*log₁₀[(5000/5)^2 X (4999/4)^2] ≈ 30.6, so Jupiter is 30.6 mag fainter at 5000 AU[/ref]).

Unless this can be sourced, it's original research. - Mike Rosoft (talk) 11:13, 8 June 2010 (UTC)[reply]

That is a simple mathematical formula used by astronomers all the time. -- Kheider (talk) 11:24, 8 June 2010 (UTC)[reply]

I can imagine the question what would Jupiter's apparent magnitude be if it were located 5000 AU from the Sun being given as a physics homework; but I don't see it as appropriate for an encyclopedia (a piece of trivia at best, even assuming that the calculation is correct). - Mike Rosoft (talk) 18:45, 9 June 2010 (UTC)[reply]

Actually it is of importance because of how dim even Jupiter would be at that distance. Astronomers can not rule out a Jupiter size object at that distance in our own solar system. -- Kheider (talk) 16:31, 10 June 2010 (UTC)[reply]

I agree with Mike Rosoft; @kheider: it might be of importance in an article on undiscovered planets, but not in this article. I boldly removed it before reading this discussion... --Roentgenium111 (talk) 22:04, 5 April 2011 (UTC)[reply]

I restored it before reading the talk page. I think it gives an important perspective on how faint even a gas giant planet would be in the Oort cloud. Since the formula used to calculate it is shown, I do not see how it harms the list. -- Kheider (talk) 01:05, 6 April 2011 (UTC)[reply]

Brightness of Moon

Throughout the article -12.6 was the value used for the brightness of the full moon. But the table gives -12.92, which changes the difference with the Sun from 400,000 time brighter to 340,000 times. I used the latter number throughout but I do not know which is correct. Please if you know which is correct edit the article to reflect that. -- Nick Beeson (talk) 19:19, 2 July 2010 (UTC)[reply]

Thank you for bringing this up Nick. The Sun is –26.74 and the mean full moon is -12.74. I have referenced the numbers in the article and changed the Sun to "398,359 times brighter than mean full moon". -- Kheider (talk) 16:51, 3 July 2010 (UTC)[reply]

There is -2.50 as 'Minimum brightness of Moon when near the sun (New Moon)' in the table. But Sirius' brightness is about -1.5 so new Moon should be 2.5 times brighter than Sirius.
WTF? Isn't this the apparent visual magnitude? And visual means what I see with my eyes. And I certainly can't see new Moon, but I do see Sirius. Something is wrong there or I just don't get it. 85.217.34.189 (talk) 01:28, 9 March 2011 (UTC)[reply]

I agree that needs explaining. Perhaps it refers to a complete crescent just risen before, or about to set after, the Sun...? Rothorpe (talk) 02:24, 9 March 2011 (UTC)[reply]

It has to do with surface area brightness. The new moon does reflect Earthshine just as a full moon dimly lights up a dark night. It is also more difficult to see a face-on galaxy of a given magnitude than it is to see an edge-on galaxy of same magnitude. -- Kheider (talk) 02:23, 11 March 2011 (UTC)[reply]

I understand the moon also reflects a little when new. But the numbers don't make sense. And, that is minimum. I'd like to know how incredibly bright it would be at maximum... And, actually there is no source cited for that new moon magnitude. So the source is quite hard to check. 85.217.44.99 (talk) 07:53, 6 April 2011 (UTC)[reply]

And, Sun is about 400 000 times brighter than mean Full Moon, but mean Full Moon only about 12 500 times brighter than minimum New Moon? This may be original research, but it cannot be so. And, as pointed above, there is no source for the -2.5 figure, so that is as much original research until cited. 82.141.127.5 (talk) 18:38, 14 May 2011 (UTC)[reply]

The ratio of 398,359 is based on the ratio for one order of magnitude being 2.5112. If you take 5 orders of magnitude to be 100, one order of magnitude is 2.51188643... and fourteen orders of magnitude (ratio between sun and mean full moon) is 398,107. I question whether the ratio should be given to six figures — can we justify this precision? Bearing in mind that 14.001 orders of magnitude — one digit more precision than any magnitude is given in the list — gives 398,474 instead of 398,107. Philbelb (talk) 12:10, 14 July 2011 (UTC)[reply]

Part of the problem is different values for the calculations are often used. -- Kheider (talk) 12:46, 14 July 2011 (UTC)[reply]

I was in no way talking about ratio accuracy. In fact, if I was putting the figure there, I would probably write "About 400,000 times brighter".

My point was brightness of new moon. If full moon was about 400,000 times brighter than new moon, new moon's brightness would then be +1.26. That I would believe to be true. Because, I think visual brightness should reflect to what I see.

And, again, there is still no source for that -2.5 figure. 85.217.15.194 (talk) 23:10, 27 July 2011 (UTC)[reply]

From my research and calculations the full moon (at perigee) is -12.86 magnitude due to being about 6% closer, compared with the magnitude at mean distance of -12.74. Also with perihelion added the sun is about 1.6% closer. The total brightness then increases to -12.90. For the new moon, it can be calculated that the magnitude is -2.5 with no crescent showing, just the Earth shine. — Preceding unsigned comment added by 174.16.248.236 (talk) 20:06, 8 September 2015 (UTC)[reply]

The moon's maximum possible brightness (as shown in the table) would be even brighter, as we'd have to add approximately .18 magnitude to the -12.90 perigee figure making it about -13.08 magnitude. There are references that discuss the opposition effect and the inadequacy of the standard magnitude forumulae, though coming up with a specific number for the moon's maximum brightness requires some interpretation. This is because only part of the opposition effect is active when we are looking at the right moment just outside of a penumbral eclipse.

Maximum brightness of Jupiter

Maximum brightness of Jupiter -2.95 2485-Oct-16 http://ssd.jpl.nasa.gov/horizons.cgi#results —Preceding unsigned comment added by Hevron1998 (talk • contribs) 13:06, 26 September 2010 (UTC)[reply]

Faintest star visible to the naked eye

This is a frivolous entry for several reasons: firstly, there is no standard "naked eye"; secondly the source is a first person account in an email on a newsgroup; and thirdly the actual quote from the source is "On occasion I also seemed to pick up another star, HD 85828" - it's rather fanciful to interpret this as "the faintest star known to be observed with the naked eye".

Any suggestions on how this could be improved? I suggest this text (first couple of pages) as a relevant source. There appears to be a significant difference between the limits of visibility in the open sky (around 6.5 to 7) and the limits of visibility when some apparatus or aperture is used to restrict the vision to a small region of sky (up to 8.1 to 8.5). — Preceding unsigned comment added by Bobathon71 (talk • contribs) 18:00, 10 July 2011 (UTC)[reply]

As there is already an entry of "7 to 8", which is more realistic, for the limit of human visibility, I've removed the line about the "faintest star known to be observed with the naked eye". Also, stars as faint as magnitude 8.44 have been observed in restricted-vision trials, with varying degrees of reliability - see document linked above (8.3 is quoted in the document, but more modern measurements give that star a magnitude of 8.44). Again, this is not a statement about "the naked eye", but about the results of that particular trial. Bobathon71 (talk) 15:25, 11 July 2011 (UTC)[reply]