Given that so many superlatives aptly describe the September 28 full moon, we hardly know where to start. It’s the most “super” supermoon of the year, and in the Northern Hemisphere, this full moon wins the title of Harvest Moon. Last but hardly least, this supermoon will present a total eclipse of the moon, visible on the night of September 27-28 from the Americas, the Atlantic, Greenland, Europe, Africa and the Middle East.
In 2015, the September 28 full moon, the Northern Hemisphere’s Harvest Moon, gives us this year’s closest supermoon. This supermoon will be about 14% closer than the micro-moon (year’s farthest full moon) on March 5, 2015. Therefore, the angular diameter of the supermoon will be some 14% greater than that of the March 5 micro-moon. However, the disk size of the September 28 supermoon will be some 30% greater than the disk of the March 5 micro-moon.
As measured from the centers of the Earth and moon, the September 28 full moon lies 356,877 kilometers (221,675 miles) away. The moon and Earth won’t make such a close encounter again until the full moon of November 14, 2016.
For general reference, we can say the moon is full all night on the night of August 10. Astronomically speaking, the moon is full at the instant that it’s most directly opposite the sun. By this definition of full moon, the moon turns full at 18:09 UTC on August 10. Universal Time refers to the standard clock time at the prime meridian of 0 degrees longitude. It translates to 1:09 p.m. CDT for us in central North America. Translate to your time zone here.
Thus, in the Americas, the full moon happens during the daylight hours today, when the moon is still beneath our horizon.
However, for much of Africa, Asia, Indonesia, Australia and New Zealand, the moon is precisely full during the nighttime hours, or sometime between sunset August 10 and sunrise August 11.
Bottom line: The August 10, 2014 full moon lies 356,896 km (221,675 miles) away. The moon and Earth won’t be so close again until the full moon of September 28, 2015. This August 2014 full moon is the closest supermoon of 2014.