The Blue Moons of 2009 and 2010

Our Blue Moon Calculator says that in 2009, there is a Blue Moon in December. You may have heard or read reports which said that the Blue Moon really occurs in January 2010 or March 2010. Who is right?

Well, you could see Blue Moons in December 2009 or in January 2010 or March 2010, but it depends where in the world you live.

Let's start with the basic astronomical facts. The Full Moons from December 2009 to March 2010 are as follows:

2 December 2009 at 07:30 GMT
31 December 2009 at 19:13 GMT
30 January 2010 at 06:17 GMT
28 February 2010 at 16:38 GMT
30 March 2010 at 02:25 GMT

These dates and times have been calculated rigorously using the same methods as those employed by the United States Naval Observatory and by Her Majesty's Nautical Almanac Office. They are given in Greenwich Mean Time (GMT) which is the standard time zone used by astronomers worldwide.

Here are those Full Moons again, but with the dates and times adjusted for several major time zones around the world. For each time zone, the two Full Moons which fall in the same calendar month are highlighted.

City Time zone Full Moon 1 Full Moon 2 Full Moon 3 Full Moon 4 Full Moon 5
Places East of Greenwich
Auckland¹ GMT + 13 hours Dec 2
20:30
Jan 1
08:13
Jan 30
19:17
Mar 1
05:38
Mar 30
15:25
Sydney¹ GMT + 11 hours Dec 2
18:30
Jan 1
06:13
Jan 30
17:17
Mar 1
03:38
Mar 30
13:25
Tokyo GMT + 9 hours Dec 2
16:30
Jan 1
04:13
Jan 30
15:17
Mar 1
01:38
Mar 30
11:25
Beijing
Perth
GMT + 8 hours Dec 2
15:30
Jan 1
03:13
Jan 30
14:17
Mar 1
00:38
Mar 30
10:25
Ho Chi Minh
(Saigon)
GMT + 7 hours Dec 2
14:30
Jan 1
02:13
Jan 30
13:17
Feb 28
23:38
Mar 30
09:25
Mumbai GMT + 5 hours 30 minutes Dec 2
13:00
Jan 1
00:43
Jan 30
11:47
Feb 28
22:08
Mar 30
07:55
Islamabad GMT + 5 hours Dec 2
12:30
Jan 1
00:13
Jan 30
11:17
Feb 28
21:38
Mar 30
07:25
Moscow GMT + 3 hours Dec 2
10:30
Dec 31
22:13
Jan 30
09:17
Feb 28
19:38
Mar 30
05:25
Johannesburg GMT + 2 hours Dec 2
09:30
Dec 31
21:13
Jan 30
08:17
Feb 28
18:38
Mar 30
06:25
Paris GMT + 1 hour Dec 2
08:30
Dec 31
20:13
Jan 30
07:17
Feb 28
17:38
Mar 30
05:25
The Greenwich Meridian
London GMT Dec 2
07:30
Dec 31
19:13
Jan 30
06:17
Feb 28
16:38
Mar 30
02:25
Places West of Greenwich
Rio de Janeiro¹ GMT - 2 hours Dec 2
05:30
Dec 31
17:13
Jan 30
04:17
Feb 28
14:38
Mar 30
00:25
New York
Toronto
GMT - 5 hours Dec 2
02:30
Dec 31
14:13
Jan 30
01:17
Feb 28
11:38
Mar 29
21:25
Chicago
Mexico City
GMT - 6 hours Dec 2
01:30
Dec 31
13:13
Jan 30
00:17
Feb 28
10:38
Mar 29
20:25
Calgary
Tucson
GMT - 7 hours Dec 2
00:30
Dec 31
12:13
Jan 29
23:17
Feb 28
09:38
Mar 29
19:25
Los Angeles
Vancouver
GMT - 8 hours Dec 1
23:30
Dec 31
11:13
Jan 29
22:17
Feb 28
08:38
Mar 29
18:25
Hawaii GMT - 10 hours Dec 1
21:30
Dec 31
09:13
Jan 29
20:17
Feb 28
06:38
Mar 29
16:25
¹ These places observe daylight saving time.

As you can see, Europe, Africa, the Americas and Asia west of India have a Blue Moon in December 2009, whilst central Asia has a Blue Moon in January 2010.

The big surprise is that the Far East, Australia and New Zealand enjoy a rare double Blue Moon in 2010, when both January and March have two Full Moons. These regions of the world missed out on the double Blue Moon back in 1999 because the second Full Moon of that year was on 1 February for time zones more than 7 hours ahead of GMT, so it's only fair that they get one in 2010 instead!

Acknowledgements

We thank Australian reader Jim Cahill for alerting us to the fact that the citizens of Western Australia voted not to switch to daylight saving time in 2009, so Perth is in the same time zone as Beijing, not Tokyo. Happily, they still get a double Blue Moon in 2010!
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Last modified on 29 January 2010
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