Super harvest moon to produce rare twilight glow

Sep 22, 2010 Dr. Tony Phillips
The Harvest Moon of Oct. 3, 2009, photographed by Catalin M. Timosca of Turda, Romania.

For the first time in almost 20 years, northern autumn is beginning on the night of a full Moon. The coincidence sets the stage for a "Super Harvest Moon" and a must-see sky show to mark the change of seasons.

The action begins at sunset on Sept 22nd, the last day of northern summer. As the sun sinks in the west, bringing the season to a close, the full Harvest Moon will rise in the east, heralding the start of fall. The two sources of light will mix together to create a kind of 360-degree, summer-autumn twilight glow that is only seen on rare occasions.

Keep an eye on the Moon as it creeps above the eastern skyline. The golden orb may appear strangely inflated. This is the Moon illusion at work. For reasons not fully understood by astronomers or psychologists, a low-hanging Moon appears much wider than it really is. A Harvest Moon inflated by the moon illusion is simply gorgeous.

The view improves as the night wears on.

Northern summer changes to fall on Sept. 22nd at 11:09 pm EDT. At that precise moment, called the autumnal equinox, the Harvest Moon can be found soaring high overhead with the planet Jupiter right beside it. The two brightest objects in the night sky will be in spectacular conjunction to mark the change in seasons.

The Harvest Moon gets its name from agriculture. In the days before electric lights, farmers depended on bright moonlight to extend the workday beyond sunset. It was the only way they could gather their ripening crops in time for market. The full Moon closest to the autumnal equinox became "the Harvest Moon," and it was always a welcome sight.

This one would be extra welcome because it is extra "Harvesty."

Usually, the Harvest Moon arrives a few days to weeks before or after the beginning of fall. It's close, but not a perfect match. The Harvest Moon of 2010, however, reaches maximum illumination a mere six hours after the equinox. This has led some astronomers to call it the "Harvestest Moon" or a "Super Harvest Moon." There hasn't been a comparable coincidence since Sept 23, 1991, when the difference was about 10 hours, and it won't happen again until the year 2029.

A Super Harvest , a rare twilight glow, a midnight conjunction—rarely does autumn begin with such celestial fanfare.

Enjoy the show!

Explore further: First-of-its-kind NASA space-weather project

Related Stories

Rare New Year's Eve 'blue moon' to ring in 2010

Dec 29, 2009

(AP) -- Once in a blue moon there is one on New Year's Eve. Revelers ringing in 2010 will be treated to a so-called blue moon. According to popular definition, a blue moon is the second full moon in a month. ...

Summer Moon Illusion

Jun 28, 2007

Sometimes you can't believe your eyes. This weekend is one of those times.

Moon, Mars bright lights in the big sky

Dec 24, 2007

The moon and Mars -- not the stars -- emitted enough wattage Monday to providing night travelers by sleigh and by foot a lighted way to their destinations.

Big Lunar Eclipse

Jun 25, 2010

(PhysOrg.com) -- This Saturday morning, June 26th, there's going to be a lunar eclipse—and for many residents of the USA, it's going to be a big one.

Get Ready For Total Lunar Eclipse Wednesday Night

Feb 19, 2008

In the late night hours of Feb. 20, 2008, a total lunar eclipse will dazzle the night sky. And this lunar eclipse may be worth staying up for, because it will be the last one until December 2010.

Recommended for you

First-of-its-kind NASA space-weather project

13 hours ago

A NASA scientist is launching a one-to-two-year pilot project this summer that takes advantage of U.S. high-voltage power transmission lines to measure a phenomenon that has caused widespread power outages ...

How many moons does Venus have?

20 hours ago

There are dozens upon dozens of moons in the Solar System, ranging from airless worlds like Earth's Moon to those with an atmosphere (most notably, Saturn's Titan). Jupiter and Saturn have many moons each, ...

User comments : 0

More news stories

How many moons does Venus have?

There are dozens upon dozens of moons in the Solar System, ranging from airless worlds like Earth's Moon to those with an atmosphere (most notably, Saturn's Titan). Jupiter and Saturn have many moons each, ...

First-of-its-kind NASA space-weather project

A NASA scientist is launching a one-to-two-year pilot project this summer that takes advantage of U.S. high-voltage power transmission lines to measure a phenomenon that has caused widespread power outages ...

Phase transiting to a new quantum universe

(Phys.org) —Recent insight and discovery of a new class of quantum transition opens the way for a whole new subfield of materials physics and quantum technologies.

Imaging turns a corner

(Phys.org) —Scientists have developed a new microscope which enables a dramatically improved view of biological cells.