A UNIQUE SUPERMOON
Dr N T Jiwaji
The full moon of November 14 is not only the closest full moon of 2016 but also the closest full moon to date in the 21st century. Such closest approach to Earth at Full Moon in any one year is popularly described as a SUPERMOON because it appears slightly larger and appreciably brighter than when it is farthest from Earth. The technical name for the closest Full Moon is perigee-syzygy.
Each year there is one Supermoon but this year’s Supermoon on Monday November 14 is very unique because it is also closest Supermoon for the past 67 years since 1948 and will not be this close again for the next 18 years until November 25, 2034.
When an object is very far from us it appears small while it will appear larger when it is closer it looks larger. The same happens to the Moon since it does not orbit the Earth in a perfect circle. Its distance changes from highest to lowest because its orbit is elliptical. The apparent size of the Moon changes depending on how far it is from Earth.
The average distance from Earth to Moon is 380,000 km and its farthest distance is 408,000 km (called apogee) while its closest distance is 357,000 km (called perigee). This is a difference of 15%, so the Moon will appear bigger in diameter by 15%. At the same time, its area will be larger by 30% (i.e. twice 15%), hence the Moon will be 30% brighter than a Full Moon when it is farthest from Earth (called a Micromoon).
The Moon is truly impressive to watch it is rising from the horizon or when it is setting. It appears large and colourful yellow or orange because blue light has been bent away by the atmosphere. A rising half Moon is a truly breathtaking sight; you will think a bright golden bowl is hanging in the sky. A Full Moon is even more striking as a large bright yellow disk, so imagine how much spectacular it will be during a Supermoon!
Though the closest distance of the Moon is this November 14, the months before and after are also considered Supermoons because they are within 90% of closest approach of the Moon. Astronomically a tighter limit of 98% is used. That is why the full Moon of November 14 is the astronomical Supermoon (perigee-syzygy) for 2016.
The closest approach of the Moon this November 14 is at 5:30pm just an hour before it rises majestically in the east at sunset. The November 14 is truly unique for this generation. So find a clear view of the east horizon so that you don't miss out on having a glance at the huge yellow bright Moon rising in the east on November 14 at sunset; and have a story to tell your friends and your children for the next 18 years until the next perigee-syzygy of 2034.