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21 August 2017: total solar eclipse



On Monday 21 August 2017 there will be a total solar eclipse, which will be visible across America (as total darkness). Some other countries in the northern hemisphere will only see part of it (partial darkness), while countries in the southern hemisphere will not see it.

A solar eclipse occurs when the Moon passes between the Earth and the Sun, totally or partly obscuring the image of the Sun. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, and turning day into darkness.

The last time a total solar eclipse was visible across the entire contiguous United States was during the 8 June 1918 eclipse. This August 2017 eclipse will be the first total solar eclipse visible from the United States since the solar eclipse of 11 July 1991, but it was only seen from parts of Hawaii, and the first since February 1979 when the total eclipse was seen from mainland United States.

This August 2017 eclipse will also be the first total solar eclipse with a path of totality crossing both the Pacific and Atlantic coasts of America since 1918.

The total eclipse will be visible within a narrow corridor 110 kilometres (70 miles) wide crossing fourteen states of the contiguous United States: Oregon, Idaho, Wyoming, Montana, Iowa, Kansas, Nebraska, Missouri, Illinois, Kentucky, Tennessee, Georgia, North Carolina, and South Carolina. It will be first seen from land in America at about 10:15 a.m.

A partial solar eclipse will be seen in all of North America, northern South America, Western Europe, some of Africa, and some of northeast Asia.

Looking directly at the Sun is unsafe except during the brief total phase of a solar eclipse (totality), when the Moon entirely blocks the Sun’s, which will happen only within the narrow path of totality.
The only safe way to look directly at the uneclipsed or partially eclipsed Sun is through special-purpose solar filters, such as eclipse glasses or hand-held solar viewers. Homemade filters or ordinary sunglasses, even very dark ones, are not safe for looking at the Sun. To date four manufacturers have certified that their eclipse glasses and handheld solar viewers meet the ISO 12312-2 international standard for such products: Rainbow Symphony, American Paper Optics, Thousand Oaks Optical, and TSE 17.

NASA offers the following advice to view a solar eclipse safely:
1. Always inspect your solar filter before use; if scratched or damaged, discard it. Read and follow any instructions printed on or packaged with the filter. Always supervise children using solar filters.
2. Stand still and cover your eyes with your eclipse glasses or solar viewer before looking up at the bright Sun. After glancing at the Sun, turn away and remove your filter — do not remove it while looking at the Sun.

3. Do not look at the uneclipsed or partially eclipsed Sun through an unfiltered camera, telescope, binoculars, or other optical device. Similarly, do not look at the Sun through a camera, a telescope, binoculars, or any other optical device while using your eclipse glasses or hand-held solar viewer — the concentrated solar rays will damage the filter and enter your eye(s), causing serious injury. Seek expert advice from an astronomer before using a solar filter with a camera, a telescope, binoculars, or any other optical device.

4. If you are within the path of totality, remove your solar filter only when the Moon completely covers the Sun’s bright face and it suddenly gets quite dark. Experience totality, then, as soon as the bright Sun begins to reappear, replace your solar viewer to glance at the remaining partial phases.

An alternative method for safe viewing of the partially eclipsed Sun is pinhole projection. For example, cross the outstretched, slightly open fingers of one hand over the outstretched, slightly open fingers of the other. With your back to the Sun, look at your hands’ shadow on the ground. The little spaces between your fingers will project a grid of small images on the ground, showing the Sun as a crescent during the partial phases of the eclipse.
There are two different types of eclipses: solar and lunar. A lunar eclipse happens at nighttime and occurs when the Earth passes between the Sun and the Moon creating a shadow on the Moon. These types of eclipses occur roughly 2 to 4 times per year. A lunar eclipse will generally last for a few hours. On 7 August 2017 there was a lunar eclipse.





MARTINA NICOLLS is an international aid and development consultant, and the author of:- Similar But Different in the Animal Kingdom (2017), The Shortness of Life: A Mongolian Lament (2015), Liberia’s Deadest Ends (2012), Bardot’s Comet (2011), Kashmir on a Knife-Edge (2010) and The Sudan Curse (2009).


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