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What is a micro Moon?

A micro full Moon is the name given to a full Moon that occurs when the moon is farthest from the Earth. The next micro full Moon will occur on Thursday, March 5, 2015.

Illustration image
A micro full Moon occurs once or twice a year.
©iStockphoto.com/Wouter van Caspel

Contrary to popular belief, the Moon orbits the Earth in an elliptical path, with one side of the path closer to the Earth than the other. The point closest to the Earth is called the perigee, while the point farthest from the Earth is known as the apogee. The average distance between the two extreme points is 237,700 miles or 382,500 km.

When a full Moon coincides with the Moon’s position at apogee, it is referred to as a micro Moon or a mini Moon. Sometimes also called an Apogee Moon, a micro Moon looks approximately 14 percent smaller, and around 30 percent less bright than a Super Moon. In reality however, there is no significant difference in the actual size of the Moon whether it is a supermoon, a micro Moon or an ordinary full Moon.

What happens if a full Moon occurs at perigee?

Defining a micro Moon

There are no universal rules as to how far away the Moon must be to qualify as a Micro Moon. timeanddate.com uses the following definition:

  • If it is further away than 400,000 kilometers at apogee, it is listed as a Micro Moon.
  • If a full moon is closer than 360,000 kilometers at perigee, it is considered a Super Full Moon.

Effects of micro Moon on Earth

Old wives' tales and folklore accounts suggest that full Moons and micro Moons affect human mental health and bring on natural disasters. Scientists have not found any evidence for any such correlation.

It has been well documented, however, that the Moon’s gravitational pull, among other forces, affects tides on earth. When the Moon is closer to the Earth or at its Perigee, it exerts high gravitational pulls, leading to high tides and a larger variation between high and low tides. On the other hand, when the Moon is at its apogee, it exerts its lowest gravitational pull, leading to low tides and a smaller variation between high and low tides. This is true irrespective of whether the Moon is a full Moon while approaching these two extreme points.

Topics: Astronomy, Moon

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All about the Moon

  1. Phases of the Moon
  2. Full Moon names
  3. The Moon's orbit
  4. Is a blue Moon blue?
  5. What is a supermoon?
  6. Micro Moon versus supermoon
  7. Moonbows
  8. Black Moon
  9. Moon Phases - definitions

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