A supermoon is the coincidence of a full moon or a new moon with the closest approach the Moon makes to the Earth on its elliptical orbit, resulting in the largest apparent size of the lunar disk as seen from Earth.
The technical name is the perigee-syzygy of the Earth-Moon-Sun system. The term “supermoon” is not astronomical, but originated in modern astrology.
Find out more amazing facts about it, here!
1. The Moon’s distance varies each month between approximately 357,000 kilometres and 406,000 km due to its elliptical orbit around the Earth (distances given are centre-to-centre).
2. A full moon at perigee is visually larger up to 14% in diameter and shines 30% more light than one at its farthest point, or apogee.
3. The association of the Moon with both oceanic and crustal tides has led to claims that the supermoon phenomenon may be associated with increased risk of events such as earthquakes and volcanic eruptions, but the evidence of such a link is widely held to be unconvincing.
4. The opposite phenomenon, an apogee-syzygy, has been called a micromoon, though this term is not as widespread as supermoon.
5. Occasionally, a supermoon coincides with a total lunar eclipse. The most recent occurrence of this was on September 27–28, 2015, while the next time will be 2033.
6. The next Supermoon Occurrence will be in November the 13-14th 2016.
7. The full moon cycle is the period between alignments of the lunar perigee with the sun and the earth, which is about 13.9443 synodic months. Thus approximately every 14th full moon will be a supermoon.
8. However, halfway through the cycle the full moon will be close to apogee, and the new moons immediately before and after can be supermoons. Thus there may be as many as three supermoons per full moon cycle.
9. Since 13.9443 differs from 14 by very close to 1⁄18, the supermoons themselves will vary with a period of about 18 full moon cycles (about 251 synodic months or 20.3 years).
10. Thus for about a decade the largest supermoons will be full, and for the next decade the largest supermoons will be new.
11. The combined effect of the Sun and Moon on the Earth’s oceans, the tide, is greatest when the Moon is either new or full.
12. At lunar perigee the tidal force is somewhat stronger, resulting in perigean spring tides. But even at its most powerful this force is still relatively weak causing tidal differences of inches at most.
13. As the tidal force follows an inverse-cube law, that force is 19% greater than average. However, because the actual amplitude of tides varies around the world, this may not translate into a direct effect.
14. It has been claimed that the supermoon of March 19, 2011 was responsible for the grounding of five ships in the Solent in the UK, but such claims are not supported by any evidence.
15. There has been media speculation that natural disasters, such as the 2011 Tōhoku earthquake and tsunami and the 2004 Indian Ocean earthquake and tsunami, are causally linked with the 1–2 week period surrounding a supermoon.
16. No evidence has been found of any correlation between supermoons with major earthquakes.
17. Winter supermoons are supersized. The Earth is closest to the sun in December each year, meaning that the star’s gravity pulls the moon closer toward the planet. Because of this effect the largest supermoons happen in the winter.
18. Supermoons will get smaller in the distant future because the moon is slowly propelling itself out of Earth’s orbit, moving 3.8 centimeters farther from Earth each year.