The distance from moon to Earth varies throughout the month and year. On average the distance is about 238,000 miles (382,900 kilometers). During a month, when the moon is furthest away from Earth it’s called apogee, when the moon is closest to Earth it is called perigee. When the full moon coincides with being closest to Earth, or perigee, it is called a supermoon. Reversely, the term Micro Moon refers to a full moon that occurs when the moon is farthest from Earth, or apogee.
No universal definition
There are no universal rules as to how close the moon must be to qualify as a supermoon. timeanddate.com uses the following definition:
If a full moon is closer than 360,000 kilometers (ca. 223,694 miles) at perigee, it is considered a supermoon.
If it is further away than 400,000 kilometers (ca. 248,548 miles) at apogee, it is listed as a Micro Moon.
Supermoons in 2014–2016
2014 Sunday, 10 August
2015 Monday, 28 September
2016 Monday, 14 November
The technical term for a supermoon is “perigee-syzygy of the Earth-Moon-Sun system”. In astronomy, the term “syzygy” refers to the straight-line configuration of three celestial bodies, which also occurs during a full moon.
Natural disaster trigger?
Although the sun and the moon’s alignment cause a small increase in tectonic activity, the effects of the supermoon on Earth are minor. Many scientists have conducted studies and haven’t found anything significant that can link the supermoon to for example natural disasters, as some astrologers claim.
Typical effects of the moon
Moon is Earth’s only natural satellite and the second brightest object in the sky after the sun. In synchrony with Earth, the moon spins at about the same speed and direction as it orbits around the Earth. This means that the same side always faces Earth, and the half of the moon’s surface that is facing outwards is never directly visible from Earth.
The tides on Earth are mostly generated by the intensity of the moon’s gravitational pull from one side of the Earth to the other. The moon’s gravity can cause small ebbs and flows in the continents called land tides or solid Earth tides. These are greatest during the full and new moons because the sun and moon are aligned on the same or opposite sides of the Earth.
See also: Most Super Moon