Topic: Great Lent!

[Ashman618]

Is just around the corner!!!!  it's hard to believe

[mike]

2 and a half months... Close?

[Eastern Mind]

  That's right!

I was going to ask my Priest if it's okay for me to celebrate Lent, or if I should wait until I am at least a Catechumen. I would like to participate in it.

[Dominika]

This year carnaval for Orthodox is so looooong (almost the longest as it's possible) so I wouldn't say it's just around the corner

[Ashman618]

2 and a half months... Close?

2 and a half months? Lent starts in February! That's next month

[Dominika]

2 and a half months... Close?

2 and a half months? Lent starts in February! That's next month

No, this year it's the 18th of March

[Ashman618]

What a rip off, I was so Excited for Pre-sanctified   

[Nephi]

2 and a half months... Close?

2 and a half months? Lent starts in February! That's next month

No, this year it's the 18th of March

But apparently the Catholic Lent begins February 13, and according to this article the Eastern Catholics begin on February 11.

Clean Monday (Monday, February 11, 2013)
Ash Wednesday (Wednesday, February 13, 2013)

[Ashman618]

2 and a half months... Close?

2 and a half months? Lent starts in February! That's next month

No, this year it's the 18th of March

But apparently the Catholic Lent begins February 13, and according to this article the Eastern Catholics begin on February 11.

Clean Monday (Monday, February 11, 2013)
Ash Wednesday (Wednesday, February 13, 2013)

I knew my grand pop told me it was right around the corner I didn't realize it was so different in Orthodoxy, sorry, I was over zealous for Lent services

[choy]

2 and a half months... Close?

2 and a half months? Lent starts in February! That's next month

No, this year it's the 18th of March

But apparently the Catholic Lent begins February 13, and according to this article the Eastern Catholics begin on February 11.

Clean Monday (Monday, February 11, 2013)
Ash Wednesday (Wednesday, February 13, 2013)

Eastern Catholics on the Gregorian Calendar that is.

Which means I still have 2 months of meat eating!  YUM!

[Nephi]

Eastern Catholics on the Gregorian Calendar that is.

Which means I still have 2 months of meat eating!  YUM!

So Eastern Catholics on the Gregorian Calendar use the Roman date for Easter?

[LBK]

Eastern Catholics on the Gregorian Calendar that is.

Which means I still have 2 months of meat eating!  YUM!

So Eastern Catholics on the Gregorian Calendar use the Roman date for Easter?

Yes.

[choy]

Eastern Catholics on the Gregorian Calendar that is.

Which means I still have 2 months of meat eating!  YUM!

So Eastern Catholics on the Gregorian Calendar use the Roman date for Easter?

Yup, its Gregorian the whole way through.  The Roman date for Easter follows the First Ecumenical Council's formula applied to the Gregorian dates.

My former parish uses Gregorian so we do have Easter on the same date as the RCs.

[Shanghaiski]

Is just around the corner!!!!  it's hard to believe

Banned--for mentioning Great Lent so close to Christmas/Theophany.

[yeshuaisiam]

When it comes, check out some vegetarian recipes on allrecipes.com

Very good stuff.  The vegetarian burgers are absolutely delicious.  Feels like cheating imho.

[Eastern Mind]

I have some vegetarian/vegan/raw cookbooks that are leftover from my vegan days. I'll still get to put them to use! ^_^ Well, at some point.

[Dominika]

Eastern Catholics on the Gregorian Calendar that is.

Which means I still have 2 months of meat eating!  YUM!

So Eastern Catholics on the Gregorian Calendar use the Roman date for Easter?

Yup, its Gregorian the whole way through.  The Roman date for Easter follows the First Ecumenical Council's formula applied to the Gregorian dates.

My former parish uses Gregorian so we do have Easter on the same date as the RCs.

Actually I think that there are 3 calendars used by Eastern Catholics: old style, new style (new julian) and gregorian. But new style is less common than old one and gregorian

[jmbejdl]

The Roman date for Easter follows the First Ecumenical Council's formula applied to the Gregorian dates.

This is, to the best of my knowledge, simply not true. The Gregorian reform included a change to how the date of Easter was calculated as well as a correction for the slipping of 21st March relative to the astronomical vernal equinox. Whether the outcome of the calculations is in some way equivalent is way beyond my mathematical ability but the formulae for working Gregorian and Julian Easter are certainly not the same.

James

[Dominika]

The Gregorian reform included a change to how the date of Easter was calculated as well as a correction for the slipping of 21st March relative to the astronomical vernal equinox. Whether the outcome of the calculations is in some way equivalent is way beyond my mathematical ability but the formulae for working Gregorian and Julian Easter are certainly not the same.

James

That's it. We Orthodox follow the rule of the 1st ecumenical council and it's not based on dates between 21st March and 26th April as Roman Catholics does it (and second rule is the first spring full moon, which we follow too). Yes, eventually, if you follow julian calendar, it will be between 21st March and 26th April (for new style of course it won't apply), but the rule is that Christian Pascha has to be after the end of Jewish Passover.

[sheenj]

The Gregorian reform included a change to how the date of Easter was calculated as well as a correction for the slipping of 21st March relative to the astronomical vernal equinox. Whether the outcome of the calculations is in some way equivalent is way beyond my mathematical ability but the formulae for working Gregorian and Julian Easter are certainly not the same.

James

That's it. We Orthodox follow the rule of the 1st ecumenical council and it's not based on dates between 21st March and 26th April as Roman Catholics does it (and second rule is the first spring full moon, which we follow too). Yes, eventually, if you follow julian calendar, it will be between 21st March and 26th April (for new style of course it won't apply), but the rule is that Christian Pascha has to be after the end of Jewish Passover.

Really? I thought part of the reason for fixing the paschalion was to not have to rely on Jewish calculations. Why should the date of the Jewish Passover matter anymore?

[biro]

Hmmmm. That's interesting.

Also, funny coincidence: just two days ago, I ran across my copy of Great Lent by Fr. Schmemann. I think I'll read it now, so I'm prepared well in advance.

[sheenj]

The Roman date for Easter follows the First Ecumenical Council's formula applied to the Gregorian dates.

This is, to the best of my knowledge, simply not true. The Gregorian reform included a change to how the date of Easter was calculated as well as a correction for the slipping of 21st March relative to the astronomical vernal equinox. Whether the outcome of the calculations is in some way equivalent is way beyond my mathematical ability but the formulae for working Gregorian and Julian Easter are certainly not the same.

James

Source? To my best knowledge the forumulae are the same, it's just the date of the paschal full moon which can throw things off.

[jmbejdl]

The Roman date for Easter follows the First Ecumenical Council's formula applied to the Gregorian dates.

This is, to the best of my knowledge, simply not true. The Gregorian reform included a change to how the date of Easter was calculated as well as a correction for the slipping of 21st March relative to the astronomical vernal equinox. Whether the outcome of the calculations is in some way equivalent is way beyond my mathematical ability but the formulae for working Gregorian and Julian Easter are certainly not the same.

James

Source? To my best knowledge the forumulae are the same, it's just the date of the paschal full moon which can throw things off.

It's the calculation of the Paschal full moon that's different, but it seems as though you're already aware of that from what you wrote above. As I said, It's way beyond my ability to tell whether the two calculations have equivalent results, but if the calculation of the Paschal full moon differs between the two calendars it seems to me that you cannot claim the formulae are the same. I believe that they are the same in relation to a given Paschal full moon, however.

James

[mike]

The Gregorian reform included a change to how the date of Easter was calculated as well as a correction for the slipping of 21st March relative to the astronomical vernal equinox. Whether the outcome of the calculations is in some way equivalent is way beyond my mathematical ability but the formulae for working Gregorian and Julian Easter are certainly not the same.

James

That's it. We Orthodox follow the rule of the 1st ecumenical council and it's not based on dates between 21st March and 26th April as Roman Catholics does it (and second rule is the first spring full moon, which we follow too). Yes, eventually, if you follow julian calendar, it will be between 21st March and 26th April (for new style of course it won't apply), but the rule is that Christian Pascha has to be after the end of Jewish Passover.

Really? I thought part of the reason for fixing the paschalion was to not have to rely on Jewish calculations. Why should the date of the Jewish Passover matter anymore?

Unfamous Zonaras Provision. Most popular Orthodox superstition.

[sheenj]

The Roman date for Easter follows the First Ecumenical Council's formula applied to the Gregorian dates.

This is, to the best of my knowledge, simply not true. The Gregorian reform included a change to how the date of Easter was calculated as well as a correction for the slipping of 21st March relative to the astronomical vernal equinox. Whether the outcome of the calculations is in some way equivalent is way beyond my mathematical ability but the formulae for working Gregorian and Julian Easter are certainly not the same.

James

Source? To my best knowledge the forumulae are the same, it's just the date of the paschal full moon which can throw things off.

It's the calculation of the Paschal full moon that's different, but it seems as though you're already aware of that from what you wrote above. As I said, It's way beyond my ability to tell whether the two calculations have equivalent results, but if the calculation of the Paschal full moon differs between the two calendars it seems to me that you cannot claim the formulae are the same. I believe that they are the same in relation to a given Paschal full moon, however.

James

The method of calculating the paschal full moon is the same. It remains the 14th of the lunar month after the equinox. The results are different because of the 13 day offset between the two calendars.

[Dominika]

The method of calculating the paschal full moon is the same. It remains the 14th of the lunar month after the equinox. The results are different because of the 13 day offset between the two calendars.

Yes, the method of full moon is the same, but the thign is that in Orthodoxy it's not unique faco in calculating the date of Pascha. And the differnce of 13 days has nothign to do with it, becasue New Style Orthodox celebrate Pascha in the same time as Old Style. And the difference between Orthodox and Roman Cathoclics (gregorian calendar I mean) will be 5 weeks!

[mike]

The method of calculating the paschal full moon is the same. It remains the 14th of the lunar month after the equinox. The results are different because of the 13 day offset between the two calendars.

Yes, the method of full moon is the same, but the thign is that in Orthodoxy it's not unique faco in calculating the date of Pascha. And the differnce of 13 days has nothign to do with it, becasue New Style Orthodox celebrate Pascha in the same time as Old Style. And the difference between Orthodox and Roman Cathoclics (gregorian calendar I mean) will be 5 weeks!

AFAIK to determine the EFM date 21 of March is needed and they use the Julian 21 of March.

[sheenj]

The method of calculating the paschal full moon is the same. It remains the 14th of the lunar month after the equinox. The results are different because of the 13 day offset between the two calendars.

Yes, the method of full moon is the same, but the thign is that in Orthodoxy it's not unique faco in calculating the date of Pascha. And the differnce of 13 days has nothign to do with it, becasue New Style Orthodox celebrate Pascha in the same time as Old Style. And the difference between Orthodox and Roman Cathoclics (gregorian calendar I mean) will be 5 weeks!

The reason the New Calendar and Old Calendar have the same Pascha is because the Revised Julian Calendar reckons Pascha according to the Old Calendar, not the New. As to the big difference between the two Paschalions this year, I think it's because the 13 day offset can make the paschal full moon fall on different months.

[jmbejdl]

The Roman date for Easter follows the First Ecumenical Council's formula applied to the Gregorian dates.

This is, to the best of my knowledge, simply not true. The Gregorian reform included a change to how the date of Easter was calculated as well as a correction for the slipping of 21st March relative to the astronomical vernal equinox. Whether the outcome of the calculations is in some way equivalent is way beyond my mathematical ability but the formulae for working Gregorian and Julian Easter are certainly not the same.

James

Source? To my best knowledge the forumulae are the same, it's just the date of the paschal full moon which can throw things off.

It's the calculation of the Paschal full moon that's different, but it seems as though you're already aware of that from what you wrote above. As I said, It's way beyond my ability to tell whether the two calculations have equivalent results, but if the calculation of the Paschal full moon differs between the two calendars it seems to me that you cannot claim the formulae are the same. I believe that they are the same in relation to a given Paschal full moon, however.

James

The method of calculating the paschal full moon is the same. It remains the 14th of the lunar month after the equinox. The results are different because of the 13 day offset between the two calendars.

No, it's really not. The Julian calendar uses a repeating 19 year (Metonic) cycle for calculating the full moon. The Gregorian is way more complicated, being based on something called the Epact (which unfortunately I am not sufficiently mathematically minded to explain but is definitely not even close to as simple as the tables used for the Julian calendar). As a result of the extra complexity of the Gregorian calculation, whereas we have a sequence of Easter dates on the Julian calendar that repeats every 532 years, on the Gregorian calendar the sequence only repeats every 5,700,000 years.

James

[sheenj]

The Roman date for Easter follows the First Ecumenical Council's formula applied to the Gregorian dates.

This is, to the best of my knowledge, simply not true. The Gregorian reform included a change to how the date of Easter was calculated as well as a correction for the slipping of 21st March relative to the astronomical vernal equinox. Whether the outcome of the calculations is in some way equivalent is way beyond my mathematical ability but the formulae for working Gregorian and Julian Easter are certainly not the same.

James

Source? To my best knowledge the forumulae are the same, it's just the date of the paschal full moon which can throw things off.

It's the calculation of the Paschal full moon that's different, but it seems as though you're already aware of that from what you wrote above. As I said, It's way beyond my ability to tell whether the two calculations have equivalent results, but if the calculation of the Paschal full moon differs between the two calendars it seems to me that you cannot claim the formulae are the same. I believe that they are the same in relation to a given Paschal full moon, however.

James

The method of calculating the paschal full moon is the same. It remains the 14th of the lunar month after the equinox. The results are different because of the 13 day offset between the two calendars.

No, it's really not. The Julian calendar uses a repeating 19 year (Metonic) cycle for calculating the full moon. The Gregorian is way more complicated, being based on something called the Epact (which unfortunately I am not sufficiently mathematically minded to explain but is definitely not even close to as simple as the tables used for the Julian calendar). As a result of the extra complexity of the Gregorian calculation, whereas we have a sequence of Easter dates on the Julian calendar that repeats every 532 years, on the Gregorian calendar the sequence only repeats every 5,700,000 years.

James

I think that's because calculating the 14th of a lunar month is a lot easier on a lunar based calendar than on a solar based calendar. The underlying formula is still the same. It's the application of the formula to a Lunar Calendar vs a Solar Calendar that creates the difference.

[jmbejdl]

The Roman date for Easter follows the First Ecumenical Council's formula applied to the Gregorian dates.

This is, to the best of my knowledge, simply not true. The Gregorian reform included a change to how the date of Easter was calculated as well as a correction for the slipping of 21st March relative to the astronomical vernal equinox. Whether the outcome of the calculations is in some way equivalent is way beyond my mathematical ability but the formulae for working Gregorian and Julian Easter are certainly not the same.

James

Source? To my best knowledge the forumulae are the same, it's just the date of the paschal full moon which can throw things off.

It's the calculation of the Paschal full moon that's different, but it seems as though you're already aware of that from what you wrote above. As I said, It's way beyond my ability to tell whether the two calculations have equivalent results, but if the calculation of the Paschal full moon differs between the two calendars it seems to me that you cannot claim the formulae are the same. I believe that they are the same in relation to a given Paschal full moon, however.

James

The method of calculating the paschal full moon is the same. It remains the 14th of the lunar month after the equinox. The results are different because of the 13 day offset between the two calendars.

No, it's really not. The Julian calendar uses a repeating 19 year (Metonic) cycle for calculating the full moon. The Gregorian is way more complicated, being based on something called the Epact (which unfortunately I am not sufficiently mathematically minded to explain but is definitely not even close to as simple as the tables used for the Julian calendar). As a result of the extra complexity of the Gregorian calculation, whereas we have a sequence of Easter dates on the Julian calendar that repeats every 532 years, on the Gregorian calendar the sequence only repeats every 5,700,000 years.

James

I think that's because calculating the 14th of a lunar month is a lot easier on a lunar based calendar than on a solar based calendar. The underlying formula is still the same. It's the application of the formula to a Lunar Calendar vs a Solar Calendar that creates the difference.

I said that I'm unsure if the results are equivalent in the my first post in this thread, however, even with that being the case I don't believe your explanation can possibly be correct. Both the Julian and Gregorian calendars are Solar, the Gregorian's just a bit more accurate. The Paschalion is all about tying together a Lunar calendar with a Solar one, regardless of whether the calendar in use is Old or New. I rather suspect that the extra complexity is a result of the change in the average length of the Solar year between the two calendars, but I'm afraid that the maths involved is not something I feel competent to delve into too deeply.

James

[sheenj]

The Roman date for Easter follows the First Ecumenical Council's formula applied to the Gregorian dates.

This is, to the best of my knowledge, simply not true. The Gregorian reform included a change to how the date of Easter was calculated as well as a correction for the slipping of 21st March relative to the astronomical vernal equinox. Whether the outcome of the calculations is in some way equivalent is way beyond my mathematical ability but the formulae for working Gregorian and Julian Easter are certainly not the same.

James

Source? To my best knowledge the forumulae are the same, it's just the date of the paschal full moon which can throw things off.

It's the calculation of the Paschal full moon that's different, but it seems as though you're already aware of that from what you wrote above. As I said, It's way beyond my ability to tell whether the two calculations have equivalent results, but if the calculation of the Paschal full moon differs between the two calendars it seems to me that you cannot claim the formulae are the same. I believe that they are the same in relation to a given Paschal full moon, however.

James

The method of calculating the paschal full moon is the same. It remains the 14th of the lunar month after the equinox. The results are different because of the 13 day offset between the two calendars.

No, it's really not. The Julian calendar uses a repeating 19 year (Metonic) cycle for calculating the full moon. The Gregorian is way more complicated, being based on something called the Epact (which unfortunately I am not sufficiently mathematically minded to explain but is definitely not even close to as simple as the tables used for the Julian calendar). As a result of the extra complexity of the Gregorian calculation, whereas we have a sequence of Easter dates on the Julian calendar that repeats every 532 years, on the Gregorian calendar the sequence only repeats every 5,700,000 years.

James

I think that's because calculating the 14th of a lunar month is a lot easier on a lunar based calendar than on a solar based calendar. The underlying formula is still the same. It's the application of the formula to a Lunar Calendar vs a Solar Calendar that creates the difference.

I said that I'm unsure if the results are equivalent in the my first post in this thread, however, even with that being the case I don't believe your explanation can possibly be correct. Both the Julian and Gregorian calendars are Solar, the Gregorian's just a bit more accurate. The Paschalion is all about tying together a Lunar calendar with a Solar one, regardless of whether the calendar in use is Old or New. I rather suspect that the extra complexity is a result of the change in the average length of the Solar year between the two calendars, but I'm afraid that the maths involved is not something I feel competent to delve into too deeply.

James

My bad, I meant Lunar BASED. IIRC, the months in the Julian Calendar are all based on the Lunar Cycle, alternating 29 and 30 days with an intercalendary month every so often, which makes the math a lot easier. The math in the Gregorian Calendar is just not going to add up as nicely since the months aren't based on the lunar cycle.

Edit: NVM, just got a chance to look it up, and I'm wrong about the months. I'll try to do some more research on the subject when I get home.

[Mockingbird]

My bad, I meant Lunar BASED. IIRC, the months in the Julian Calendar are all based on the Lunar Cycle, alternating 29 and 30 days with an intercalendary month every so often, which makes the math a lot easier. The math in the Gregorian Calendar is just not going to add up as nicely since the months aren't based on the lunar cycle.

Edit: NVM, just got a chance to look it up, and I'm wrong about the months. I'll try to do some more research on the subject when I get home.

You were right the first time.  The Julian lunar calendar presupposes lunar years consisting of lunar months of (formally) 30 and 29 days.  The Gregorian lunar calendar does the same.  The difference is that the Julian lunar months are around 4 days late, while the Gregorian lunar months stay reasonably close to the visible moon.    So the Gregorian full moon is on Thursday this week, April 25, 2013, the same day as the astronomical full moon, while the Julian full moon (in this case the Julian Paschal full moon or νομικον φασκα) is not until the Tuesday of next week, April 30th, 2013, 5 days later.

[jmbejdl]

My bad, I meant Lunar BASED. IIRC, the months in the Julian Calendar are all based on the Lunar Cycle, alternating 29 and 30 days with an intercalendary month every so often, which makes the math a lot easier. The math in the Gregorian Calendar is just not going to add up as nicely since the months aren't based on the lunar cycle.

Edit: NVM, just got a chance to look it up, and I'm wrong about the months. I'll try to do some more research on the subject when I get home.

You were right the first time.  The Julian lunar calendar presupposes lunar years consisting of lunar months of (formally) 30 and 29 days.  The Gregorian lunar calendar does the same.  The difference is that the Julian lunar months are around 4 days late, while the Gregorian lunar months stay reasonably close to the visible moon.    So the Gregorian full moon is on Thursday this week, April 25, 2013, the same day as the astronomical full moon, while the Julian full moon (in this case the Julian Paschal full moon or νομικον φασκα) is not until the Tuesday of next week, April 30th, 2013, 5 days later.

Then, as I said in the first place, the formulae are not the same - the correction to the solar date for the vernal equinox is not the only thing that the Gregorian reform changed, if what you write is correct. As you're saying that there is a 4 day difference between the full moon as used in the Gregorian calculations and that used in the Julian, then it means that the dates of Easter still might be a week apart, even if we were to tie our calculations to the New Calendar equinox.

James

[sheenj]

My bad, I meant Lunar BASED. IIRC, the months in the Julian Calendar are all based on the Lunar Cycle, alternating 29 and 30 days with an intercalendary month every so often, which makes the math a lot easier. The math in the Gregorian Calendar is just not going to add up as nicely since the months aren't based on the lunar cycle.

Edit: NVM, just got a chance to look it up, and I'm wrong about the months. I'll try to do some more research on the subject when I get home.

You were right the first time.  The Julian lunar calendar presupposes lunar years consisting of lunar months of (formally) 30 and 29 days.  The Gregorian lunar calendar does the same.  The difference is that the Julian lunar months are around 4 days late, while the Gregorian lunar months stay reasonably close to the visible moon.    So the Gregorian full moon is on Thursday this week, April 25, 2013, the same day as the astronomical full moon, while the Julian full moon (in this case the Julian Paschal full moon or νομικον φασκα) is not until the Tuesday of next week, April 30th, 2013, 5 days later.

Then, as I said in the first place, the formulae are not the same - the correction to the solar date for the vernal equinox is not the only thing that the Gregorian reform changed, if what you write is correct. As you're saying that there is a 4 day difference between the full moon as used in the Gregorian calculations and that used in the Julian, then it means that the dates of Easter still might be a week apart, even if we were to tie our calculations to the New Calendar equinox.

James

You mean they use the MOON to determine the LUNAR cycle? Is outrage! 

[LizaSymonenko]

The method of calculating the paschal full moon is the same. It remains the 14th of the lunar month after the equinox. The results are different because of the 13 day offset between the two calendars.

Yes, the method of full moon is the same, but the thign is that in Orthodoxy it's not unique faco in calculating the date of Pascha. And the differnce of 13 days has nothign to do with it, becasue New Style Orthodox celebrate Pascha in the same time as Old Style. And the difference between Orthodox and Roman Cathoclics (gregorian calendar I mean) will be 5 weeks!

AFAIK to determine the EFM date 21 of March is needed and they use the Julian 21 of March.

I was always taught the date depended on the "Paschal Full Moon", which is calculated from tables created back in 325 AD at the Council of Nicea.  These tables do not jive with actual visual lunar cycles, however, they keep us all celebrating together.

http://en.wikipedia.org/wiki/Paschal_Full_Moon

Notionally, the paschal full moon refers to the ecclesiastical full moon of the northern spring used in the determination of the date of Easter. The name "paschal" is derived from "Pascha", a transliteration of the Greek word, which is itself a transliteration of the Hebrew pesach, both words meaning Passover. The date of Easter is determined as the first Sunday after the paschal full moon. This "full moon" does not currently correspond directly to any astronomical event, but is instead the 14th day of a lunar month, determined from tables. It may differ from the date of the actual full moon by up to two days.[1] The use of tables instead of actual observations of the full moon is useful and necessary since the full moon may occur on different dates depending where one is in the world.

[podkarpatska]

Over the years I have read so many conflicting explanations attempting to explain the Orthodox calculation that I have given up trying to figure anything out about the calculation except to just look it up. 

[mike]

Over the years I have read so many conflicting explanations attempting to explain the Orthodox calculation that I have given up trying to figure anything out about the calculation except to just look it up. 

+1

[jmbejdl]

My bad, I meant Lunar BASED. IIRC, the months in the Julian Calendar are all based on the Lunar Cycle, alternating 29 and 30 days with an intercalendary month every so often, which makes the math a lot easier. The math in the Gregorian Calendar is just not going to add up as nicely since the months aren't based on the lunar cycle.

Edit: NVM, just got a chance to look it up, and I'm wrong about the months. I'll try to do some more research on the subject when I get home.

You were right the first time.  The Julian lunar calendar presupposes lunar years consisting of lunar months of (formally) 30 and 29 days.  The Gregorian lunar calendar does the same.  The difference is that the Julian lunar months are around 4 days late, while the Gregorian lunar months stay reasonably close to the visible moon.    So the Gregorian full moon is on Thursday this week, April 25, 2013, the same day as the astronomical full moon, while the Julian full moon (in this case the Julian Paschal full moon or νομικον φασκα) is not until the Tuesday of next week, April 30th, 2013, 5 days later.

Then, as I said in the first place, the formulae are not the same - the correction to the solar date for the vernal equinox is not the only thing that the Gregorian reform changed, if what you write is correct. As you're saying that there is a 4 day difference between the full moon as used in the Gregorian calculations and that used in the Julian, then it means that the dates of Easter still might be a week apart, even if we were to tie our calculations to the New Calendar equinox.

James

You mean they use the MOON to determine the LUNAR cycle? Is outrage! 

I didn't opine as to whether it was right or wrong to actually use the moon, only disagreed with the assertion that the Gregorian formula is the same as the Julian. That the tables used to calculate the Paschal moon don't actually agree to observations is something I thought was reasonably well known (much as the drift in the Julian as compared to Gregorian calendars). I'm actually of the opinion that we ought to sort out the calendar so that we use either all Julian or all New throughout. Don't mistake my wanting to point out that the two calculations are not the same for advocating the Old Calendar calculations.

James

[sheenj]

My bad, I meant Lunar BASED. IIRC, the months in the Julian Calendar are all based on the Lunar Cycle, alternating 29 and 30 days with an intercalendary month every so often, which makes the math a lot easier. The math in the Gregorian Calendar is just not going to add up as nicely since the months aren't based on the lunar cycle.

Edit: NVM, just got a chance to look it up, and I'm wrong about the months. I'll try to do some more research on the subject when I get home.

You were right the first time.  The Julian lunar calendar presupposes lunar years consisting of lunar months of (formally) 30 and 29 days.  The Gregorian lunar calendar does the same.  The difference is that the Julian lunar months are around 4 days late, while the Gregorian lunar months stay reasonably close to the visible moon.    So the Gregorian full moon is on Thursday this week, April 25, 2013, the same day as the astronomical full moon, while the Julian full moon (in this case the Julian Paschal full moon or νομικον φασκα) is not until the Tuesday of next week, April 30th, 2013, 5 days later.

Then, as I said in the first place, the formulae are not the same - the correction to the solar date for the vernal equinox is not the only thing that the Gregorian reform changed, if what you write is correct. As you're saying that there is a 4 day difference between the full moon as used in the Gregorian calculations and that used in the Julian, then it means that the dates of Easter still might be a week apart, even if we were to tie our calculations to the New Calendar equinox.

James

You mean they use the MOON to determine the LUNAR cycle? Is outrage! 

I didn't opine as to whether it was right or wrong to actually use the moon, only disagreed with the assertion that the Gregorian formula is the same as the Julian. That the tables used to calculate the Paschal moon don't actually agree to observations is something I thought was reasonably well known (much as the drift in the Julian as compared to Gregorian calendars). I'm actually of the opinion that we ought to sort out the calendar so that we use either all Julian or all New throughout. Don't mistake my wanting to point out that the two calculations are not the same for advocating the Old Calendar calculations.

James

The Gregorian calendar still places Pascha on the Sunday after the Paschal full moon, which is the 14th of the first lunar month following March 20th. The methodology remains the same, however, the calculation is what differs because the Julian calendar uses the uncorrected Metonic cycle to determine the lunar months. The 4-5 day drift between the two cycles is because of this difference, not a difference in methodology.

[Mockingbird]

Both Gregorian and Julian computations are based on the same equation:

235 synodic lunar months = 19 Julian years + correction.

The Julian computation set the correction to zero.  This gives an average synodic lunar month of 29.530851 days.

The Gregorian computation sets the correction to 8 days in 2500 Gregorian years.  When averaged over many cycles,
this gives an average synodic lunar month of 29.530587 days.  

The astronomical value is currently 29.530589 days, and is slowly (very slowly) decreasing in terms of contemporary mean solar days.  (In Claudius Ptolemy's time it was around 29.530594 days).  So the Julian value is presently too long by .000262 days per lunar month or about a day in 309 years.  The Gregorian value is too short by .000002 days per lunar month, or about 1 day in 40,226 years.

Whether or not setting the correction to a value other than zero constitutes a "difference in methodology" depends on one's definition of "methodology".  The observed differences between Eastern and Western Easter are (as someone has already noted) due to the accumulation of errors in the Julian calendar over the centuries, creating what is now a large systematic error in the Julian tabular equinox and the Julian tabular lunar phases, relative to the astronomical phenomena they were originally intended to approximate.

For convenience of future reference by those posting to this thread, here is the full 19-year list of paschal full moons for both systems.  Easter, Eastern or Western, is the Sunday after the Paschal full moon. (Yes, it's really that simple!)  The Gregorian column is valid until 2200.  The Julian column is valid until 2100.  The present year, 2013, is the 19th and last year of the cycle according to the numbering system used here.  Next year, 2014, will be the first year of a new 19-year cycle.

Code: [Select]

                                Gregorian date
Year of cycle | Gregorian PFM | of Julian PFM (νομικον φασκα)
-------------  --------------  ---------------
1             | April 14      | April 18
2             | April 3       | April 7
3             | March 23      | April 26
4             | April 11      | April 15
5             | March 31      | April 4
6             | April 18      | April 23
7             | April 8       | April 12
8             | March 28      | May 1
9             | April 16      | April 20
10            | April 5       | April 9
11            | March 25      | April 28
12            | April 13      | April 17
13            | April 2       | April 6
14            | March 22      | April 25
15            | April 10      | April 14
16            | March 30      | April 3
17            | April 17      | April 22
18            | April 7       | April 11
19            | March 27      | April 30


[Mockingbird]

The Gregorian computation sets the correction to 8 days in 2500 Gregorian years.

To be a bit more precise, the correction is a deletion of 8 days in 2500 Gregorian years, and might have been expressed better as "-8" than as "8".