Skywatchers should definitely be on alert on September 27, if they want to feast their eyes on an incredibly special supermoon, combined with a lunar eclipse.
During the celestial event, the Moon will be in its full phase, and at the closest possible distance in its orbit around Earth, thus appearing as a “supermoon”, approximately 30% brighter and 14% larger than normally.
The reason why supermoons occur is related to the fact that the Moon’s trajectory around Earth is shaped like an ellipse instead of a circle, bringing the Moon approximately 30,000 miles closer to earth some times (at perigee), than other times (at apogee).
In practice, however, it is difficult to distinguish between regular full moons and supermoons, due to natural occurrences masking their luminosity (clouds, fog etc.)
The reason why September’s supermoon is particularly memorable is that it will occur in conjunction with a total lunar eclipse, which is also the last eclipse of 2015. During such an event, the Earth is positioned in a straight line with the Sun and the moon, between the two of them, impeding the sun’s direct rays from reaching the moon’s surface.
Nevertheless, the moon doesn’t become completely dark, because it passes behind the Earth, into its shadow, and still receives sunlight refracted by the Earth’s atmosphere, which causes it to acquire a reddish tone. As a result of this mechanism, called Rayleigh scattering, total Moon eclipses are also nicknamed “blood moons”.
The last time a “blood moon” converged with a “supermoon” was in 1982, and the next time such an event will grace our skies will be in 2033, according to a newly released NASA video. Since 1910, the combination of the two occurrences has happened just 5 times, making the sky show particularly rare and unique.
The phenomenon will begin after sunset and last for around 3 hours. According to Timeanddate.com, it is expected that people will be able to observe it from most of the Americas, Europe, western Asia and some regions of Africa. A partial solar eclipse will also take place on September 13, but only those in southern Africa will be able to view it.
For American skywatchers, the celestial event on September 27 will have the best visibility from the East Coast and parts of Central U.S., between moonrise and midnight. Weather permitting, those keen on witnessing the red supermoon will enjoy a striking show starting from 9:07 p.m. Eastern time.
Image Source: Flickr