The full moon this weekend is not any old month, it will be a blue moon, according to NASA.
But no, it really isn't to be blue.
Apparently there are two ways to have a blue moon.
The most famous definition of the blue moon is to have two full months in one calendar month – the second is called the blue moon.
According to NASA, it happens on average every 2.5 years.
But another way to define the blue moon is as the third full moon in one season with four full moons. That definition goes back to 1528, and that is what was used for the full moon this weekend.
Astronomical springs (in the northern hemisphere) stretch from the spring equinox on March 20 to the summer solstice on June 21.
During that period there will be four full months:
1. March 20 (worm month)
2. April 19 (pink moon)
3. May 18 (flower moon and blue moon)
4. June 17 (strawberry month)
Since months the strawberries have come before the solstice which made four full months during the spring. It also makes Saturday's full moon a blue moon.
According to EarthSky astronomers, the last seasonal blue moon is on May 21, 2016.
The moon will reach 100 percent fullness on Saturday afternoon at 4:12 a.m. CDT, according to NASA, will appear fully from Friday night to the weekend.
Full moon May also has several other nicknames.
Native Americans use their own names for the full moon every month, according to Farmers Almanak, who first began publishing names in the 1930s.
The full moon in May is also called the flower month, the month of planting corn and the moon of milk.
The next blue moon will fall on Halloween in 2020, according to the National Weather Service.
There have it's been a really blue moon, but it's rare. One better known example was in 1883 when the Indonesian volcano Krakatau erupted, spewing tons of ash high into the atmosphere.
The particles that make up the ash are small enough to spread red light and let other colors shine, according to NASA – making the moon look blue.
The blue moon is seen for years after the eruption.
Blue moons have also been seen recently after volcanic eruptions – including Mount St. Helens in Washington state in 1980. Forest fires can have the same effect.
The moon rises at 6:35 a.m. CDT Friday night in Birmingham and will be set at 5:46 Saturday. This will go up again at 7:40 a.m. Saturday night and set at 6:27 Sunday morning. The last month on the weekend will go up at 8:42 a.m. Sunday. Click here to see the time in your area.