This Friday , moon gazers in the Northern Hemisphere will be treat by a twice special full moon as the Harvest Moon coincide with the notoriously superstitious Friday the 13th ,   an natural event that only go on once in every 20 yr , according to theFarmer ’s Almanac .

The Harvest Moon marks the start of declination as the days get shorter and the gentle wind generate crisper . ( At least for the northerly one-half of the world . For those living in the Southern Hemisphere , the Harvest Moon broadly occurs in March or early April . ) This year ’s autumnal equinox is on September 23 , and a brightly lit Harvest Moon will allow reaper ample clip to work latterly into the night collecting the last of this year ’s summertime crops . Some sources say the renowned moon traces back to ancient aboriginal American custom , though modern record argue Anglo - Saxons recorded its occurrence as betimes as the eighth   100 , according totimeanddate.com .

Like any other full moon , a number of factors characterize the Harvest Moon , peculiarly the prison term of moonrise . During most of the yr , the synodic month rises around 50 mo by and by each solar day . Near the equinox , the Harvest Moon lift close   to sundown , concord toEarthSky.org . Those survive in mid - temperate parallel may even see the moonrise just 25 to 30 arcminute later in the day – high northerly altitudes , even less .

This yr ’s Harvest Moon is also a “ micro- “ or “ mini - moon ” and will look 14 percent smaller than other full moons in 2019 . This is because the Moon will be at its greatest distance from the Earth .

“ The Moon will be full early Saturday break of the day ,   September   14 , 2019 , appear " polar " the Sun ( in Earth - based longitude ) at 12:33 AM EDT . The Moon will appear full for about three solar day centered around this time , from Thursday night through Sunday morning , ” concord toNASA Science .

The agency mention that the brightest planet in the sky on September 14 will be Jupiter , “ appearing in the due south - southwest at about 24 stage above the sensible horizon . ” Saturn will also come along in the Confederacy at around 29 degrees above the horizon .