August will have its second full moon of the month on Friday.
The first full moon of the month was on Aug. 1. And while this astronomical rarity is sometimes referred to as a Blue Moon, do not expect to look up and see the moon’s bright face be blue!
Two full moon’s in one month occasionally happens every two or three years. The next Blue Moon will be in July 2015.
So then is a moon ever really blue? It sure can, but it requires a disturbance to the atmosphere, such as a volcanic eruption, according to NASA.
When the Indonesian volcano Krakatoa erupted in 1883, people reportedly saw Blue Moons every night, according to NASA.
Krakatoa's ash was the reason. Some of the plumes were filled with particles 1 micron wide, about the same as the wavelength of red light. Particles of this special size strongly scatter red light, while allowing blue light to pass through. Krakatoa’s clouds thus acted like a blue filter.
There were also Blue Moons reported after the El Chichon volcano erupted in Mexico in 1983; Mt. St. Helens in 1980; and Mount Pinatubo in 1991.
Large forest fires can also cause us to see a Blue Moon, according to NASA.
But then again, Blue Moons do not have to be only blue.
Often, when the moon is hanging low, it looks red for the same reason that sunsets are red. The atmosphere is full of aerosols much smaller than the ones injected by volcanoes. Measuring less than a micron in diameter, these aerosols scatter blue light, while leaving the red behind. For this reason, red Blue Moons are far more common than blue Blue Moons.
So look up at the sky on Friday and double check to see if the moon is really blue or not!
The West Orange Patch is also looking for the best picture of the full moon this Labor Day weekend!
Whether you are in West Orange or away this weekend, take a photo of the moon and upload it.
The best picture will win a Patch iPhone cover and T-shirt!