The full harvest supermoon shone brightly in the night sky Tuesday evening. A partial lunar eclipse, with a “bite” taken from the moon, was also visible.

If you happened to notice the supermoon looking especially large as it was rising, you may have fallen victim to a “well-known, poorly studied optical illusion,” said NASA’s Noah Petro. Here’s the scientific explanation of what you were seeing,

Not only is September's full moon also a so-called "supermoon" because of its size and brightness, but it's also due to be eclipsed by Earth.

The skies will light up Tuesday night with a double lunar phenomenon: the Harvest supermoon and a partial lunar eclipse. Supermoons are full moons that appear larger because they happen in tandem with the lunar orbit’s closest approach to earth.

A supermoon is what happens when a full moon coincides with perigee, or when the moon is closest to the Earth, and it looks bigger than normal.

As the Earth passes between the sun and the moon, a fleeting shadow will be cast on the planet's only natural satellite on Tuesday.

It's called the "harvest moon" because its bright light would shine down late into the night while the early settlers worked on bringing in the September harvest.

FOX 26 Chief Meteorologist Mike Iscovitz explains the partial lunar eclipse expected to be seen in the Houston area/ If conditions are just right, the moon might look slightly reddish. Most of the time partial lunar eclipses are disappointing,