As I was on my way to work, I noticed how full and bright the moon looked and being the ever curious person I am, I decided to find out why. So I spoke with some friends at MoonConnection.com, and boy did they lay out some facts about that giant rock in the sky.
First the reason for the moon being so big and bright. It turns out that in addition to the 4 normal phases of the moon, there are 2 additional stages. Known as the apogee and the perigee. Apogee is the furthest point from the earth. Perigee is the closest point to the earth and it is in this stage that the moon appears larger. Looking at the moon in the sky without anything to compare it to, you wouldn't notice any size difference. But the difference in size can in fact be quite significant. The apogee and perigee of the moon have an effect on the tides here on Earth. When the moon is at apogee, the furthest distance from the Earth, it has less gravitational pull which, along with other factors that influence the tides, can contribute to lower tides or lower variation in the high/low tide level. When the moon is at perigee, closer to the Earth, there is much more gravitational pull which contributes to the opposite effect: higher tides or greater variation in the high and low tide.
We currently are in the perigee of course, and this occurs every 27.3 days, while the full moon occurs every 29.4 days, so the two events do not occur at the same time, but every now and then we get the special treat that will occur tonight.
That’s it in a nut shell. So while we may only see 59% of the lunar surface, go out and enjoy the view in all its’ natural glory.