Blue Moons

[CometPhoenix]

When and why do they occur? Don't they happen every 4 years, or something? (I really don't know, that's why I'm asking) <div class="Discussion_UserSignature"> <font color="#0000ff"><p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="3" color="#0000ff">What ever happens, happens/</font><font face="Times New Roman"><font color="#0000ff"><font size="3">Just call me Phoenix</font></font></font></p></font> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>When and why do they occur? Don't they happen every 4 years, or something? (I really don't know, that's why I'm asking) <br /> Posted by CometPhoenix</DIV></p><p>&nbsp;</p><p>http://www.astronomycafe.net/qadir/amoonb.html</p><p>&nbsp;</p><p>Google is your friend <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-wink.gif" border="0" alt="Wink" title="Wink" /> </p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[CometPhoenix]

<p>2 things:</p><p>1) How do you read UT? I google searched it a few months ago and all I got was charts of UT, so my question was never answered</p><p>2) Does this chart seem weird to you?&nbsp;This is supposed to a chart of the next blue moons. Why is it that they are all on the last day of the month? Btw, that site was wrong about the lunar month. A lunar month is approximately 27 days, 7 hours, and 43 minutes.</p><table border="0" cellspacing="0"><tbody><tr><td valign="middle"><p>Year</p>

 

[CometPhoenix]

<p>Sorry that chart is so long. It didn't look that way when I copied it.</p> <div class="Discussion_UserSignature"> <font color="#0000ff"><p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="3" color="#0000ff">What ever happens, happens/</font><font face="Times New Roman"><font color="#0000ff"><font size="3">Just call me Phoenix</font></font></font></p></font> </div>

 

[derekmcd]

<p>The moon is like a clock that never needs adjusting.&nbsp; It's cycles are very repetitious and very predictible.</p><p>as for UTC time, I think it's -4 hours for EDT unless it daylight savings time, then its -5.&nbsp; Just start start in greenwich and count timezones backwards. </p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[MeteorWayne]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>2 things:1) How do you read UT? I google searched it a few months ago and all I got was charts of UT, so my question was never answered2) Does this chart seem weird to you?&nbsp;This is supposed to a chart of the next blue moons. Why is it that they are all on the last day of the month? Posted by CometPhoenix</DIV><br /><br />The definition of a Blue Moon is the second full moon of a month. So it will always be in the last few days of a month, with the first full moon occurring on the first day or two. </p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[MeteorWayne]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The moon is like a clock that never needs adjusting.&nbsp; It's cycles are very repetitious and very predictible.as for UTC time, I think it's -4 hours for EDT unless it daylight savings time, then its -5.&nbsp; Just start start in greenwich and count timezones backwards. <br />Posted by derekmcd</DIV><br /><br />You have that reveresed. EST is UT -5 hours, EDT is UT -4 hours. </p><p>I know that becasue my watch is always set to UT (for meteor observing) and I mentally subtract the correct number of hours to get the local time.</p><p>&nbsp;</p><p>In other words 1200 (noon) UT is 7am EST in winter, and 8 AM EDT in summer.</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>You have that reveresed. EST is UT -5 hours, EDT is UT -4 hours. I know that becasue my watch is always set to UT (for meteor observing) and I mentally subtract the correct number of hours to get the local time.&nbsp;In other words 1200 (noon) UT is 7am EST in winter, and 8 AM EDT in summer. <br /> Posted by MeteorWayne</DIV></p><p>Unless my brain is going goofy on me, I think I got it right.&nbsp; Daylight Savings Time is EST right?&nbsp;</p><p>[I see my mistake now... I got the EDT right, just referred to EST as DST instead of EDT]</p><p>too many friggin acronyms <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-laughing.gif" border="0" alt="Laughing" title="Laughing" /> </p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[MeteorWayne]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Unless my brain is going goofy on me, I think I got it right.&nbsp; Daylight Savings Time is EST right?&nbsp;[I see my mistake now... I got the EDT right, just referred to EST as DST instead of EDT]too many friggin acronyms <br />Posted by derekmcd</DIV><br /><br />OK, lets eliminate the acronyms..<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-smile.gif" border="0" alt="Smile" title="Smile" /></p><p>&nbsp;</p><p>EST= Eastern Standard Time= UT -5 hours (7AM EST = 1200 UT) . November through Frebruary</p><p>EDT= Eastern Daylight Time= UT -4 hours (8AM EDT= 1200 UT) March through October.</p><p>Blue Moon, 2nd new moon in a month...note that UT Blue Moons may not be the same as EST or EDT new moons!!</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>OK, lets eliminate the acronyms..&nbsp;EST= Eastern Standard Time= UT -5 hours (7AM EST = 1200 UT) . November through FrebruaryEDT= Eastern Daylight Time= UT -4 hours (8AM EDT= 1200 UT) March through October.Blue Moon, 2nd new moon in a month...note that UT Blue Moons may not be the same as EST or EDT new moons!! <br /> Posted by MeteorWayne</DIV></p><p>&nbsp;</p><p>LOL... i was just reading the wiki on UTC, or is it UT, TIA, UT1, maybe GMT... TUC, CUT, UT1R, DUT, DUT1, UTO???&nbsp; They're all the same!!!&nbsp;</p><p>Whatever happened to Beer Thirty with PBRs and MGDs?&nbsp;</p><p>Might as well add ZULU in there.&nbsp; Wouldn't want the USAF and NOAA to get FUBAR </p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[MeteorWayne]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;LOL... i was just reading the wiki on UTC, or is it UT, TIA, UT1, maybe GMT... TUC, CUT, UT1R, DUT, DUT1, UTO???&nbsp; They're all the same!!!&nbsp;Whatever happened to Beer Thirty with PBRs and MGDs?&nbsp;Might as well add ZULU in there.&nbsp; Wouldn't want the USAF and NOAA to get FUBAR <br />Posted by derekmcd</DIV><br /><br />Indeed. I use UT, even though I should use UTC, but I'm afraid if I have too much T, I'll drown in my own TP.</p><p>Yes the time systems are amazingly diverse, I find it a fascinating subject. I think there's a proposed new one called Absolute Time, counting from billions of years ago; perhaps it's one of those acronyms. And don't forget GPS time.</p><p>Wonder how many of us even know what PBR is??</p><p>I saw on the news two days ago some guy has his future coffin made up as a can of it!!</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[doublehelix]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Wonder how many of us even know what PBR is??I saw on the news two days ago some guy has his future coffin made up as a can of it!! <br /> Posted by MeteorWayne</DIV></p><p>Pabst Blue Ribbon!&nbsp; Not a fan here (I'm actually a fan of Blue Moon beer, tho).&nbsp; <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-smile.gif" border="0" alt="Smile" title="Smile" /></p><p>I was amazed that someone would love PBR so much they'd make it part of their coffin.&nbsp; Different strokes. </p><p>Saw this bit from Wikipedia:</p><p>The following Blue Moons occur between 2005 and 2015. These dates use UTC as the timezone, months will vary with different timezones.</p> <p>If the Farmer's Almanac definition of blue moon is taken (meaning the third full moon in a season of four full moons) then blue moons occur:</p> <ul><li>August 19, 2005</li><li>February 21, 2008</li><li>November 21, 2010</li><li>August 21, 2013</li></ul> <p>However, if the "Calendar Blue Moon" definition is taken (meaning the second full moon in any given month) then blue moons occur:</p> <ul><li>June 30, 2007</li><li>December 31, 2009</li><li>August 31, 2012</li><li>July 31, 2015</li></ul> <p>It is worth noting that the year 2018 (as well as 2037, 1961, 1942, 1999 etc.) will have two "calendar blue moons" (i.e. a second full moon in a given month) in January and March, but no full moon in February (i.e. a black moon).</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p><font color="#3366ff">doublehelix, Community Manager<br />Imaginova </font></p> </div>

 

[MeteorWayne]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>It is worth noting that the year 2018 (as well as 2037, 1961, 1942, 1999 etc.) will have two "calendar blue moons" (i.e. a second full moon in a given month) in January and March, but no full moon in February (i.e. a black moon).&nbsp; <br />Posted by doublehelix</DIV><br /><br />Ahhh, February 2018...a good month for warmly dressed meteor observers!!<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-tongue-out.gif" border="0" alt="Tongue out" title="Tongue out" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[CometPhoenix]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>The definition of a Blue Moon is the second full moon of a month. So it will always be in the last few days of a month, with the first full moon occurring on the first day or two. &nbsp; <br />Posted by MeteorWayne</DIV><br /><br />I understand that, but the chart indicates that they occur, on average, every 4 years, and on the last day of the month <strong>everytime</strong>. If the lunar month is about 27 days, then it should be impossible for a blue moon to occur on the last day of the month <strong>everytime</strong>. Sometimes is more believable, but not everytime.</p><p>That doesn't make sense. What makes this 2nd full moon any more special than any other full moon? Does the atmosphere change or something if there 2 full moons in 1 month? That's another thing, months is something humans made up in order to keep track of time. Blue moons have been there for at least a couple billion years.</p><p>Can you guys explain what all of those acronyms mean? Because you guys definitely lost me.</p> <div class="Discussion_UserSignature"> <font color="#0000ff"><p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="3" color="#0000ff">What ever happens, happens/</font><font face="Times New Roman"><font color="#0000ff"><font size="3">Just call me Phoenix</font></font></font></p></font> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I understand that, but the chart indicates that they occur, on average, every 4 years, and on the last day of the month everytime. If the lunar month is about 27 days, then it should be impossible for a blue moon to occur on the last day of the month everytime. Sometimes is more believable, but not everytime.That doesn't make sense. What makes this 2nd full moon any more special than any other full moon? Does the atmosphere change or something if there 2 full moons in 1 month? That's another thing, months is something humans made up in order to keep track of time. Blue moons have been there for at least a couple billion years.Can you guys explain what all of those acronyms mean? Because you guys definitely lost me. <br /> Posted by CometPhoenix</DIV></p><p>&nbsp;</p><p>The lunar cycle is actually 29.53 days.&nbsp; The 27 days you are referring to is the Sidereal Month.&nbsp; The Sidereal month is when the moon return the the same spot using the fix position of the stars.&nbsp; Because the earth is moving in relation to the stars, it only 27 days.<br /><br />Let's see if some numbers will help clear it up for ya.<br /><br />There are 365.24 days in a year.&nbsp; Multiply this times 4 to account for the leap year (366 days once every 4 years).&nbsp;&nbsp; This gives us a 4 year cycle of 1460.96 days.&nbsp; We'll go with 1461 days to make it a bit easier.&nbsp;&nbsp; The lunar cycle is 29.53 days.&nbsp; This give us 12.36 full moons per year or an average of 1.03 per calendar month.&nbsp; This give us 49.4 full moons every 4 solar years or 48 calendar months.&nbsp; With this, we can say that, on occasion, there will be 2 full moons in 1 month. </p><p>With 12 calendar months in a year, we get an average of 30.44 day for each month.&nbsp;&nbsp; So, we can say, with the lunar month being 29.53 days, it is nearly 1 day less than the calendar month.&nbsp; Every month, the full moon starts about 1 day earlier than the previous month.<br /><br />Given the fact that a full moon can fall on any day of the month, the only time you will see 2 in 1 month is when the first full moon falls on the 1st of the month.&nbsp; 29.5 days later will be the 31st.&nbsp; Given that there are not 2 months in a row with 31 days, it will not be common to see one fall on the 30th day of a month with 31 days.&nbsp; If you extend the chart out far enough, you probably would see the occasional blue moon on the 30th day of a 31 day month, but it wouldn't be very common. </p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[MeteorWayne]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp; Given that there are not 2 months in a row with 31 days, it will not be common to see one fall on the 30th day of a month with 31 days.&nbsp; If you extend the chart out far enough, you probably would see the occasional blue moon on the 30th day of a 31 day month, but it wouldn't be very common. <br />Posted by derekmcd</DIV><br /><br />Nice summary an excellent explanation.&nbsp;except there are&nbsp;two sets of&nbsp;31 day months in a row, twice a year. July/Aug and Dec/ Jan. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[MeteorWayne]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>What makes this 2nd full moon any more special than any other full moon? Does the atmosphere change or something if there 2 full moons in 1 month? That's another thing, months is something humans made up in order to keep track of time. Blue moons have been there for at least a couple billion years.Can you guys explain what all of those acronyms mean? Because you guys definitely lost me. <br />Posted by CometPhoenix</DIV><br /><br />Nothing makes it special, it's just a name.</p><p>VERY rarely atmospheric conditions can produce an actual blue moon, or so I've heard, but that has nothing to do with the nonscientific "Blue Moon" of popular culture.</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Nice summary an excellent explanation.&nbsp;except there are&nbsp;two sets of&nbsp;31 day months in a row, twice a year. July/Aug and Dec/ Jan. <br /> Posted by MeteorWayne</DIV></p><p>Good catch.&nbsp; No clue how I pulled that supposition out of my arse.&nbsp; I can understand missing the dec/jan connection, but I guess I just screwed the pooch on Aug.</p><p>Since you brought that up...</p><p>Strictly speaking in the calendar sense, how many days there are in the month doesn't matter.&nbsp; Since the first full moon, in a month with 2, can only be on the first day of the month, it only depends what time the new moon starts.&nbsp; I was, originally, going to expand on the 30/31 alternating months in correlation with the fact that the lunar month is 29.5<strong><em>3</em></strong> days.&nbsp; Work out the odds because it is slight over a half day more than 29.&nbsp; I couldn't come to a quick conclusion, so I gave up not wanting to spend too much time on it.&nbsp; I'm sure had a spend a little more time on it, I would have realized the mistake.</p><p>So, in conclusion, with MeteorWayne's help...</p><p>As seen by the 2 months where the 2nd full moon falls on the 30th, one can conclude that it can also fall on the 30th day of a 31 day month simply depending on what time of day it started on the 1st.&nbsp; It just so happens that chart is but a small enough sample, you don't see any.&nbsp;</p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[MeteorWayne]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Good catch.&nbsp; No clue how I pulled that supposition out of my arse.&nbsp; I can understand missing the dec/jan connection, but I guess I just screwed the pooch on Aug.Since you brought that up...Strictly speaking in the calendar sense, how many days there are in the month doesn't matter.&nbsp; Since the first full moon, in a month with 2, can only be on the first day of the month, it only depends what time the new moon starts.&nbsp; I was, originally, going to expand on the 30/31 alternating months in correlation with the fact that the lunar month is 29.53 days.&nbsp; Work out the odds because it is slight over a half day more than 29.&nbsp; I couldn't come to a quick conclusion, so I gave up not wanting to spend too much time on it.&nbsp; I'm sure had a spend a little more time on it, I would have realized the mistake.So, in conclusion, with MeteorWayne's help...As seen by the 2 months where the 2nd full moon falls on the 30th, one can conclude that it can also fall on the 30th day of a 31 day month simply depending on what time of day it started on the 1st.&nbsp; It just so happens that chart is but a small enough sample, you don't see any.&nbsp; <br />Posted by derekmcd</DIV><br /><br />Yes if a&nbsp;full moon occurred at 0001 UTC on the 1st, the second would be on the 30th just after noon. If the chart went on long enough, such an early full moon would intersect a 31 day month, hence not be on the last day of the month.</p><p>&nbsp;</p><p>But they would be (are) rare.</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Yes if a&nbsp;full moon occurred at 0001 UTC on the 1st, the second would be on the 30th just after noon. If the chart went on long enough, such an early full moon would intersect a 31 day month, hence not be on the last day of the month.&nbsp;But they would be (are) rare.&nbsp; <br /> Posted by MeteorWayne</DIV></p><p>&nbsp;</p><p>Hmmm... the more I think about it, it's probably not that rare.&nbsp; It's more cyclical than anything.&nbsp; As seen on the schedule provided, there are already 2 days falling on the 30th.&nbsp;&nbsp;</p><p>Consider the lunar cycle is 29.53 days.&nbsp; That translates into the first full moon having to start on or before 1117 UTC for there to be a 2nd on the 30th.&nbsp; Given the cylical, predictible nature of the moon, if you plotted it out over a long time period, the odds of a full moon beginning at 1117 UTC would be 47%.&nbsp; Hence a 47% chance of the 2nd landing on the 30th of any given month. </p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[MeteorWayne]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp;Hmmm... the more I think about it, it's probably not that rare.&nbsp; It's more cyclical than anything.&nbsp; As seen on the schedule provided, there are already 2 days falling on the 30th.&nbsp;&nbsp;Consider the lunar cycle is 29.53 days.&nbsp; That translates into the first full moon having to start on or before 1117 UTC for there to be a 2nd on the 30th.&nbsp; Given the cylical, predictible nature of the moon, if you plotted it out over a long time period, the odds of a full moon beginning at 1117 UTC would be 47%.&nbsp; Hence a 47% chance of the 2nd landing on the 30th of any given month. <br />Posted by derekmcd</DIV></p><p>Not sure what you mean with the 47%</p><p>The odds of a full moon on the 1st before noon in any given month are 1 in 60.8 (30.4 x 2).</p><p>That's 1.6% per month. Times 12=19.7% a year.</p><p>Of course, only 7 months are 31 days, so 1.6% x 7= ~ 11.5% annual chance of there being a blue moon is a given year not on the last day.</p><p>&nbsp;</p><p>I think that's right, but not sure at all!<img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-foot-in-mouth.gif" border="0" alt="Foot in mouth" title="Foot in mouth" /></p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Not sure what you mean with the 47%The odds of a full moon on the 1st before noon in any given month are 1 in 60.8 (30.4 x 2).That's 1.6% per month. Times 12=19.7% a year.Of course, only 7 months are 31 days, so 1.6% x 7= ~ 11.5% annual chance of there being a blue moon is a given year not on the last day.&nbsp;I think that's right, but not sure at all! <br /> Posted by MeteorWayne</DIV></p><p>Your math is correct, but you are factoring in years that don't have 13 full moons in a year.&nbsp; Every year only has a 36% chance to have 13 full moons.&nbsp; That's once every 2.7 years.&nbsp; That would bump up your number to 31% to not be on the last day of the month.</p><p>The 47% is describing only months in which there are 2 full moons.&nbsp; The conclusion being, during months in which there is a blue moon, that blue moon (the 2nd full moon) has a 47 percent chance of landing on the 30th.&nbsp; I came to this conclusion by 763.2 minutes being 53% of a 24 hour day... 47% the way through 24 hours is 1117 UTC.&nbsp; Any full moon after 1117 UTC will fall on the 31st.&nbsp; </p><p>I wasn't considering, specifically, the last day of 31 day months.&nbsp; Just of it landing on the 30th in any month that has 2 full moons.&nbsp; If we take it the next step and consider, like you are, <strong><em>only</em></strong> the last day...</p><p>Eleven months available to have a blue moon (can't count feb.).&nbsp; Four months have 30 days and will be 100% on the last day.&nbsp; Seven months with 31 days at 53% is 3.7 times out of 7 available months it will land on the 31st.&nbsp; This gives a 30% chance it will land on the 30th of the 31 day month which is in line with your numbers.&nbsp; </p><p>Mine is 1% lower than yours because I'm operating on 47% versus your 50%. </p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[MeteorWayne]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Posted by derekmcd</DIV><br /><br />OK, now I understand. Hopefully readers know what both of us mean. For a minor naming convention (Blue Moon) this has been fun and educational for all of us!</p><p>That's why we Astronomers get the big bucks!</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[derekmcd]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>OK, now I understand. Hopefully readers know what both of us mean. For a minor naming convention (Blue Moon) this has been fun and educational for all of us!That's why we Astronomers get the big bucks! <br /> Posted by MeteorWayne</DIV></p><p>&nbsp;</p><p>Next time someone say "once in a blue moon", I'm gonna pull a Cliff Clavin on them. <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-laughing.gif" border="0" alt="Laughing" title="Laughing" /> </p> <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[doublehelix]

<p>If we went to a lunar calendar, then I guess "blue moons" would be moot... kind of a sad idea.</p><p>-dh&nbsp;</p> <div class="Discussion_UserSignature"> <p><font color="#3366ff">doublehelix, Community Manager<br />Imaginova </font></p> </div>