NASA image of the Moon showing two halves to illustrate the difference in the apparent size and brightness of the moon during a supermoon. Credit: NASA / Goddard / Lunar Reconnaissance Orbiter.
On the night of February 19-20, the skies will host an astronomical phenomenon called the snow supermoon.
During this period two circumstances converge: the satellite is in perigee , the closest point to Earth; and the Moon is in its full moon phase. As a result, it will appear 14% larger than usual and 30% brighter in the skies.
As for its name, the origin may seem disappointing: according to NASA, it is simply due to the fact that this astronomical phenomenon coincides with the snow season in the northern hemisphere.
Why do supermoons occur?
As the Moon orbits the Earth, it goes through several phases, which are determined by its position relative to the Earth and the Sun. When the Moon lines up on the opposite side of the Earth from the Sun, we see the full moon. Instead, the phase of the new moon occurs when the Moon and the Sun are aligned on the same side of the Earth.
The Moon travels in an ellipse that takes it further and further from Earth in its orbit. The farthest point on this ellipse is called the apogee and is about 405,500 kilometers from Earth on average. Its closest point is perigee, which is an average distance of about 363,300 kilometers from Earth. During each 27-day orbit around the Earth, the Moon reaches both its apogee and its perigee.
Full moons can occur at any point along the Moon’s elliptical path, but when a full moon occurs at or near perigee, it looks slightly larger and brighter than a typical full moon. That’s what the term ‘supermoon’ refers to.
Because ‘supermoon’ is not an official astronomical term, there is no definition of how close the Moon has to be to perigee to be considered as such. In general, ‘supermoon’ is used to refer to a full moon at 90% or more of the maximum distance at its perigee.
What will you see during a supermoon
As with anything that comes closest to the person viewing it, the supermoon will appear larger than the average full moon, but the difference is not very significant at first glance. At its largest size, it can appear 14% larger in diameter than the smallest full moon (equivalent to the size of something that can be covered with a fingernail on an arm extended skyward).
If the full moon is bright in and of itself, the supermoon is even brighter. Sunlight that reflects off the Moon during its full phase is bright enough to cast shadows on the ground. During a supermoon, that brightness can increase up to 30% as a result of the Moon being closer to Earth.
Yes indeed; NASA warns that superfluous do not cause extreme weather events , such as floods, earthquakes, fires, volcanic eruptions, or tsunamis, despite what some incorrect and unscientific speculators may suggest.
