This Friday, a rare total solar eclipse will be visible across parts of Greenland, Europe, and North Africa. Not only is this the only total solar eclipse in 2015, but it’s the last of its kind for another 19 years. (Sadly for the US, the eclipse won’t be visible from North America but here’s how to watch live online.)
There are a few things that makes this eclipse so rare:
It’s the only total solar eclipse of 2015. Total solar eclipses are pretty rare just by themselves. On average, there are usually only one to two total solar eclipses a year. After Friday’s event, there are four more total solar eclipses taking place between now and the year 2020.
(Romeo Durscher/NASA Goddard Space Flight Center/Flickr)It’s the first total solar eclipse of the 21st century that occurs on the same day as the first day of spring. To have the moon block out the sun on the same day as the vernal equinox, the first day of Spring, is even more rare.
It won’t happen again until the year 2034.
And after that, the only other two such events will be in 2053 and 2072 before the next turn of the century.
Certain solar eclipses occur in periodic cycles and this one is part of the Saros cycle 120 — a highly studied set of eclipses.
The Saros cycle 120 refers to a very specific set of solar eclipses that take place every 18 years and is visible from the same regions on Earth because of where in space the moon and Earth are relative to the sun. The first documented Saros cycle solar eclipse took place in 933 AD. The next one in the cycle will take place on March 30 in 2033. There are other Saros cycles that refer either to other solar eclipses with different alignments between the earth, moon, and sun or certain lunar eclipses.
And to top it off, the moon will look larger than usual during Friday’s event. The moon isn’t always the same distance from Earth in its orbit. When it’s either a full moon or a new moon and is closest to Earth, like the new moon on Thrusday, March 19, we call it a supermoon. Full moons that are also supermoons can appear as much as 14% larger in the sky.
There are, on average, four to six supermoons every year.
Don’t expect a spectacular view of the supermoon this time around, though. It’s really only impressive when it is full, but sadly, a solar eclipse can only take place when the moon is between Earth and the sun, which is also when the moon is in it’s new moon phase, which is invisible in our night sky.
The next supermoon that coincides with a brilliantly bright full moon will be this year on September 27, and, unlike tomorrow’s event, everyone with clear skies will get a chance to see the show.