Although Harvest Moon sounds more like the title of a Twilight film, it is actually a term to describe the full moon closest in time to the autumnal equinox. This year, the Harvest Moon came only 6 hours after the autumnal equinox, putting it at September 22 at 11:09 PM EST — and it was a sight to see. In fact, last night’s was a “super harvest moon,” according to NASA.
In order for Jupiter and the moon to shine all night long on any equinox, these three events – the opposition of Jupiter, the full moon and the equinox – all have to happen in close proximity to each other. For the Harvest Moon 2010, the three events lined up perfectly with the whole process taking only two days.
Astronomer Tony Phillips spoke with the Associated Press and explained that Jupiter will seem especially bright because of its close proximity to Earth–just 368 million miles away — the closest it has been since 1963. Jupiter will stay close to Earth but won’t appear this bright until 2022 when it makes another close pass. Phillips goes on to say this type of harvest moon is especially rare because it appears on the exact night summer ends and fall begins. This hasn’t happened since September 23, 1991, and it won’t happen again until 2029.
Did you see it last night?