The full moon known as this year’s Harvest Moon — a moon that appears bigger and brighter than usual due to its close proximity to earth — rises tonight coincided with a minor, penumbral lunar eclipse for many people in Asia and Africa. That won’t happen again until 2024.
Moonrise for several days around the time of the full moon closest to the autumnal equinox occurs nearly at sunset. Before artificial lighting, this gave farmers extra time to cut and move ripened crops. Hence, the full moon closest to autumnal equinox is called Harvest Moon. According to NASA, this can make it seem as if there is a full moon for several nights in a row. Because all this extra light it provided in the early evenings was helpful for harvest crews working long days, it became known as the harvest moon.
The Harvest Moon this year falls in September, although occasionally this title can be bestowed upon the October full moon. That will happen 12 times from 1970 to 2020, occurring next in 2017. The 2016 version of the Harvest Moon comes six days prior to the autumnal equinox, although it can occur as early as September 8 (as it did in 2014) or as late as October 7 (as happened in 1987).
What sets the Harvest Moon apart from other full moons is that it occurs at the climax of the harvest season, so farmers can work late into the night by the moon’s light. This moon rises at about the time the sun sets, and — more importantly — at this time of year, instead of rising its normal average of 50 minutes later each day, the moon seems to rise at somewhat the same time each night. In other words, most nights the moon rises an average of 50 minutes later than it did the day before, but around this time of year that difference is only 30 minutes.
Is the Harvest Moon bigger, or brighter or more colorful? Not necessarily. It’s different every year. But the 2016 Harvest moon does count as a bigger-than-average full moon. That’s because this full moon is near perigee, the closest point to Earth in its monthly orbit. This full moon comes today (September 16) at 19:05 UTC.
The Harvest Moon is undergoing an eclipse of sorts tonight, although this event is not affording viewers much of a spectacle. It’s a “penumbral” eclipse, which occurs when the moon passes through the outer fringe of the Earth’s shadow. Unlike when the moon interacts with the dark umbral shadow of Earth, resulting in a noticeable “bite” out of the lunar disk, a penumbral eclipse at best causes a tarnishing or “smudginess” on the moon at maximum effect.
Because the sun is a large disk rather than a single point of light, our planet’s shadow also has a lighter outer cone, or penumbra, that can also envelop the moon. When this penumbral eclipse happens, it creates a subtle shading of the lunar disk. It needs a telescope to clearly see the effect of penumbra on the moon.
Eclipse began today (September 16) at 16:54:42 (UTC) and will continue until 20:53:59 (UTC). Lunar eclipses look approximately the same all over the world and happen at the same time.