Image above is via Flickr user Tim Geers
Meteors ahead! Everything you need to know: Perseid meteor shower
Tonight – July 31, 2014 – you’ll see a moon in the sky that looks full and round. In fact, for some of us, tonight’s moon is past full. The crest of the moon’s full phase is on July 31 at 10:43 UTC (6:43 a.m. EDT, 5:43 a.m. CDT, 4:43 a.m. MDT or 3:43 a.m. PDT on the morning of July 31). No matter. This will be a popular full moon! It’s the second of two July 2015 full moons, and – although it won’t look blue in color – by popular acclaim, it’ll be called by the name Blue Moon.
How often do we have a Blue Moon in July? For the answer, you have to look to a concept from astronomy and calendar studies, at what’s called the Metonic cycle.
The Metonic cycle is a period of 19 calendar years (235 lunar months), after which the new and full moons return to the same (or nearly the same) dates of the year.
Therefore, 19 years from now, in 2034, we’ll again have another Blue Moon in July.
And 19 years after that, there will be another one, in July, 2053.
There are 235 full moons (235 lunar months) yet only 228 calendar months in the 19-year Metonic cycle. Because the number of full moons outnumber the number of calendar months, that means at least seven of these 228 calendar months must harbor two full moons (235 – 228 = 7 extra full moons).
However, if a February within this 19-year period has no full moon at all – as is the case in February, 2018 – that means this extra 8th full moon must fall into the lap of another calendar month, as well. Therefore, the year 2018 actually sports two Blue Moons, in January and March of 2018, giving us a total of 8 Blue-Moon months in the upcoming 19-year Metonic cycle:
1. January 31, 2018
2. March 31, 2018
3. October 31, 2020
4. August 31, 2023
5. May 31, 2026
6. December 31, 2028
7. September 30, 2031
8. July 31, 2034
Bottom line: The second of two July 2015 full moons falls today, on July 31, 2015. By popular acclaim, the second full moon to occur in a single calendar month is known as a blue moon. Thanks to what is called the Metonic cycle, 19 years from now, in 2034, we’ll again have another Blue Moon in July. And 19 years after that, there will be another one, in July, 2053.
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from EarthSky http://ift.tt/1JzRxvi
Image above is via Flickr user Tim Geers
Meteors ahead! Everything you need to know: Perseid meteor shower
Tonight – July 31, 2014 – you’ll see a moon in the sky that looks full and round. In fact, for some of us, tonight’s moon is past full. The crest of the moon’s full phase is on July 31 at 10:43 UTC (6:43 a.m. EDT, 5:43 a.m. CDT, 4:43 a.m. MDT or 3:43 a.m. PDT on the morning of July 31). No matter. This will be a popular full moon! It’s the second of two July 2015 full moons, and – although it won’t look blue in color – by popular acclaim, it’ll be called by the name Blue Moon.
How often do we have a Blue Moon in July? For the answer, you have to look to a concept from astronomy and calendar studies, at what’s called the Metonic cycle.
The Metonic cycle is a period of 19 calendar years (235 lunar months), after which the new and full moons return to the same (or nearly the same) dates of the year.
Therefore, 19 years from now, in 2034, we’ll again have another Blue Moon in July.
And 19 years after that, there will be another one, in July, 2053.
There are 235 full moons (235 lunar months) yet only 228 calendar months in the 19-year Metonic cycle. Because the number of full moons outnumber the number of calendar months, that means at least seven of these 228 calendar months must harbor two full moons (235 – 228 = 7 extra full moons).
However, if a February within this 19-year period has no full moon at all – as is the case in February, 2018 – that means this extra 8th full moon must fall into the lap of another calendar month, as well. Therefore, the year 2018 actually sports two Blue Moons, in January and March of 2018, giving us a total of 8 Blue-Moon months in the upcoming 19-year Metonic cycle:
1. January 31, 2018
2. March 31, 2018
3. October 31, 2020
4. August 31, 2023
5. May 31, 2026
6. December 31, 2028
7. September 30, 2031
8. July 31, 2034
Bottom line: The second of two July 2015 full moons falls today, on July 31, 2015. By popular acclaim, the second full moon to occur in a single calendar month is known as a blue moon. Thanks to what is called the Metonic cycle, 19 years from now, in 2034, we’ll again have another Blue Moon in July. And 19 years after that, there will be another one, in July, 2053.
Donate: Your support means the world to us
Enjoying EarthSky so far? Sign up for our free daily newsletter today!
from EarthSky http://ift.tt/1JzRxvi
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