Harvest Moon, Jupiter, equinox on September 23

September 23rd, 2010 – Tonight
The Harvest Moon and the blazing planet Jupiter shine all night long tonight to commemorate the first full night of the autumn season. By common practice, we use the September equinox to mark the start of autumn, and call the closest full moon to the autumnal equinox the Full Harvest Moon. In 2010, the Harvest Moon comes only 6 hours after the September equinox.

If you live in the southern hemisphere, the September equinox signals the beginning of spring, and this full moon counts as the first full moon of spring.
The September equinox falls on Thursday, September 23, at 3:09 Universal Time. Converting the equinox time to North American clocks, that places the equinox on Wednesday, September 22, at 11:09 p.m. Eastern Time, 10:09 p.m. Central Time, 9:09 p.m. Mountain Time and 8:09 p.m. Pacific Time. For more on the equinox see yesterday’s program.

For the moon and Jupiter to shine all night long on any equinox, these three events – the opposition of Jupiter, the equinox and full moon – all have to happen in close conjunction. In 2010, the three events follow one another like falling dominos, with the whole procession taking less than two days time.

September 2010 presents the only time in your lifetime that you’ll be able to witness the moon and Jupiter’s simultaneous all-night appearance on the equinox. On this the first full night of autumn, watch the Harvest Moon and Jupiter as they sail westward across the sky tonight!