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You might be able to see a rare 'moonbow' in Metro Vancouver skies

The breathtaking display is far less common than a rainbow.
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The March full moon is a worm moon in 2023 and may include a moonbow because the moon will be low on the horizon in Metro Vancouver, B.C.

While you've probably heard of a rainbow, there's another, rarer optical phenomenon that you can observe in the sky. 

A "moonbow" is actually very similar to a rainbow but the source of light is reflected off of the moon rather than the sun, H.R. MacMillan Space Centre Astronomer Marley Leacock told V.I.A.

"From what I understand, a moonbow is very similar to a rainbow. The difference is that the source of light is coming from the sunlight reflected off of the Moon, instead of the Sun itself," she explained. 

Moonbows are rarer than rainbows because several things need to work together to make one:

  • the Moon has to be low in the sky 
  • the moon has to be full or nearly full
  • there must be a dark sky to see it 
  • water droplets need to be in the sky opposite the Moon. (Moonbows tend to be more common in places that have waterfalls for this reason.)

Vancouver weather and the intensity of a moonbow

Unlike some vibrant rainbows, moonbows tend to be less "intense" and people don't often see the colours. Instead, it usually "looks white," Leacock described. 

"The colours are there, but they are less intense and our eyes have trouble seeing them. The colours come out during long exposure photography," she said.

In the city, light pollution may obscure the chances of seeing one of the rare phenomena. 

Outside of the city, the best bet for seeing a moonbow is near a waterfall when the moon rises or sets. That is when it is closest to the horizon, in the hours after sunset or before sunrise, Leacock noted.

Known as the full "worm moon," the March moon will appear at its fullest in Metro Vancouver overnight on Monday, March 6, reaching its fullest point at 4:14 a.m. on Tuesday, March 7 morning, according to timeanddate.com. 

On March 7, the ideal time to see a moonbow will be just after 7:15 p.m. On March 8, it will be just before 6:30 a.m. The Moon will rise in the eastern sky and set in the west.

While you don't need any special equipment to view the full moon, a clear viewing is always weather dependent.