You may have heard of a blue moon but what about a pink moon? This coming weekends ‘pink moon’ will reach peak fullness at 4:12 a.m. PST on Friday (for U.S based readers!). While this Friday’s moon will no doubt be spectacular even it won’t be pink.
The nickname ‘pink moon’ was given to the April full moon by Indigenous Americans as it occurred around the same time a pink spring flower was blooming.
While the moon won’t be pink it will still be a wraith site to see. To make the most of the April full moon the best time to bask in its splendor is when it rises and sets. Try and find a moon watching position without too many obstacles and look to the horizon where the moon will rise.
The moon will appear closer there and will also have less glare making it easier to look at. The moon will start out a bold orange gradually fading to a milky white color as it rises. The moon's color and in fact all the colors we see up in the sky are thanks to Rayleigh scattering.
The earth's atmosphere is rich in oxygen and nitrogen, these molecules absorb some wavelengths of light more than others. The sun's light hits these molecules and then depending on the length of the wavelength appear differently to our eyes.
For example, the sun's light with very short wavelengths such as purple and blue are more easily absorbed and scattered by the oxygen and nitrogen molecules. That is why the sky is blue. However, colors with long wavelengths pass easily through the atmosphere.
Long wavelength colors include yellow, orange and red, which is why we see fantastically bright colors when viewing the moon or sun close to the horizon where the atmosphere is thickest. For best viewing check your local moon rise and set times.
What even is a full moon?
The visibility of the moon from the Earth is tracked according to lunar phases. A full moon is when the moon appears whole or fully illuminated from Earth. This occurs roughly when the Earth is located right between the Sun and the Moon. Or more precisely when the ecliptic longitudes of the Sun and Moon differ by 180°.
In other words, the moon is completely sunlight and appears to us from the earth as a round white disk. The full moon occurs roughly every month. Despite the moon appearing huge, the full moon is not a good time for astronomical observation as most of the moon's shadows vanish.
Even checking on other stars can be difficult as the moon's bright light can outshine them. This weekend's moon isn’t just going to look good for many belief systems around the world, the ‘pink’ moon also has cultural significance.