Once in a Blue Moon

Today we have a blue moon – the second full moon in July 2015.

Image result for blue moon

An average lunar cycle is 29.53 day so two full moons can sometimes fit into one calendar month, but it depends on what time zone you are in as this list from Wikipedia shows:

  • 2009: December 2, December 31 only in time zones west of UTC+05.
  • 2010: January 1 (partial lunar eclipse), January 30, only in time zones east of UTC+04:30.
  • 2010: March 1, March 30, only in time zones east of UTC+07.
  • 2012: August 2, August 31, only in time zones west of UTC+10.
  • 2012: September 1, September 30, only in time zones east of UTC+10:30.
  • 2015: July 2, July 31.
  • 2018: January 2, January 31, only in time zones west of UTC+11.
  • 2018: March 2, March 31, only in time zones west of UTC+12.
  • 2020: October 1, October 31 only in time zones west of UTC+10.

Sometimes (rarely) the blue can actually look blue-ish.

The effect can be caused by smoke or dust particles in the atmosphere, as has happened after forest fires in Sweden and Canada in 1950 and 1951, and after the eruption of Krakatoa in 1883, which caused the moon to appear blue for nearly two years.

Other less potent volcanoes have also turned the moon blue. People saw blue moons in 1983 after the eruption of the El Chichón volcano in Mexico, and there are reports of blue moons caused by Mount St. Helens in 1980 and Mount Pinatubo in 1991

Ella Fitzgerald does a nice Blue Moon (Richard Rodgers and Lorenz Hart, 1934),

Leave a comment


  1. kittycatkin

     /  31st July 2015

    Thank you. They usually mention this on the news, but in case they don’t, it’s good to know.

    I’d love to see one that was really blue, as none that I have seen are very much blue coloured, and when I first looked out after the weather presenter said that there was one that night, I realised that I’d seen them before and not known that they were blue moons.

    I love shooting stars.

  2. kittycatkin

     /  31st July 2015

    Right on cue at this year’s dawn parade, a shooting star (or maybe more than one, I forget now) shot across the sky.

  3. Mike C

     /  31st July 2015

    I just went outside to fetch something from the shed, and the night sky was so brightly lit up by the full moon that I didn’t need to turn on any outside lights.

    The moon was mostly hidden behind some clouds whilst I was out there, so God only knows how light it would have been if the clouds hadn’t been there.

    • kittycatkin

       /  1st August 2015

      It was huge at one point, wasn’t it ? And very bright indeed; you should have seen it when it was fully visible. Then it was smaller, but bluer, and had the prettiest orange halo round it. Thank you, Pete-the weather didn’t mention this, so I wouldn’t have known.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: