Total solar eclipse – 20 March 2015

As probably most of you already know, tomorrow morning 20 March 2015 there will be a total solar eclipse!

Let’s see what will happen…

Tomorrow the Moon and the Sun will be in conjunction as seen from the Earth, and as the Moon passes between the Sun and the Earth it will occult the Sun. The eclipse will be total, which means that the Moon will completely obscure the bright disk of the Sun.

The darkest part of the shadow of the Moon, the so-called umbra, marks the area where the eclipse is seen as total (see figure below), while the larger light grey area (the penumbra) is the area where the eclipse is seen as partial.

Geometry of a solar eclipse
Geometry of a solar eclipse (from Wikipedia)

Total solar eclipses are a rare occasion to observe the solar corona (the hottest part of the solar atmosphere, with a very complicated fine structure), which is not normally visible because the photosphere (the innermost region of the Sun, where most of the visible light comes from) is much brighter than the corona.

This particular solar eclipse is especially rare, Universe Today reports that this is the first total solar eclipse to coincide with the vernal equinox (the day when the Northern and Southern Hemispheres are illuminated equally) since 20 March 1662!

In the figure below, you can have a look at the path of the Moon’s umbra during tomorrow eclipse (blue C-shape arc). It will start at 9:13 UT about 700 km south of Greenland, it will move eastward just south of Iceland, and then it will turn north over the Arctic Ocean.

Orthographic map that shows the global visibility of the eclipse
Orthographic map that shows the global visibility of the eclipse (from NASA)

The only two places where it will be possible to experience the total solar eclipse will be the Faroe Islands (situated between the Norwegian Sea and the North Atlantic Ocean), and the Norwegian archipelago of Svalbard (situated in the Arctic Ocean).

A detailed display of the eclipse’s path can be found here, and here you can find a useful explanation to read the orthographic map.

Most of Europe, North Africa, Greenland and West Asia will get a partial view of the solar eclipse, but if you’re not lucky and you will not be able to see the eclipse, don’t be sad! The Slooh Community Observatory will broadcast the total eclipse from Faroe Islands (http://live.slooh.com/stadium/live/the-total-solar-eclipse-of-2015).

If you are going to look up at this spectacular event, remember that it’s quite dangerous for your eyes to look directly at the Sun! Safe approaches are using telescopes fitted with solar filters, or build a pinhole camera.

And if you are so lucky to be in Faroe Islands or Svalbard… in Faroe Islands you should be pretty safe (predicted temperature for tomorrow is about 6 to 8 C), but if you happen to be in Svalbard, remember to dress warmly (predicted temperature for tomorrow ranges from -10 to -21 C). Of course everything will depend on the cloud coverage…