NASA advise people to take a good long look at the moon as it travels across the sky tonight. They say that one may notice that it looks a little different. According to NASA's Dr. Tony Phillips, you'll see the "moon illusion" at work. It will look abnormally large -- an optical illusion that comes about when the moon sits lower than usual in the sky.
The last time the Super Harvest Moon occur was in September 23, 1991, but even then it was a 10-hour difference, and according to Science@NASA we won't see it like this again until the year 2029.
The celestial events happening which starts with the super harvest moon will also produce other events.
- On September 22 at 11:09 p.m. EDT (0309 GMT Thursday, Sept. 23), when the sun crosses the celestial equator — a projection of Earth's equator on the sky — and enters the southern hemisphere. This is known as the equinox, meaning "equal nights." Daytime and nighttime are of equal length, about 12 hours, everywhere on Earth. (Of course, the sun won’t be visible at this time in North America, being on the other side of the planet.)
- Finally, at 5:17 a.m. EDT (0917 GMT) Thursday, the full moon of September will occur, since the moon will be exactly opposite the sun in the sky. This is a special full moon: It is the full moon closest to the equinox, known as the harvest moon.