August solar eclipse: What you need to know

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On Monday, Aug. 21, all of North America — as well as parts of South America, Europe and Africa — will, weather permitting, be able to view a partial eclipse of the sun. A total eclipse will be viewable to the select 12.2 million Americans living within the path of totality, a 70-mile band stretching across 14 states from Oregon to South Carolina.
The moon will pass between the earth and the sun on a west to east trajectory and completely eclipse the sun first in Lincoln Beach, Oregon at 10:16 a.m. PDT and last in Charleston, South Carolina at 2:48 p.m. EDT. The longest period of totality will occur in Carbondale, Illinois for a full 2 minutes and 40 seconds, with this interval being shorter in other places. This is the first time in 100 years that a total eclipse has crossed the span of the continent.

Why solar eclipses occur
The moon moves in an orbit around the Earth, which in itself orbits the sun. Even though the sun is in fact many times bigger than the moon, due to the vast difference between where these two celestial bodies are located, they appear to be roughly the same size when viewed from Earth. When the moon’s trajectory overlaps the sun’s position in relation to a given point on Earth, we experience either a partial or total eclipse, a phenomenon that generally takes place over a three-hour period.

Viewing the eclipse safely
Eclipses are inspiring natural occurrences that can and should be admired. However, certain precautions need to be taken when viewing them. In general, staring at the sun’s surface for too long can cause damage to the eye, but during an eclipse, the surrounding darkness sways the natural tendency to divert one’s gaze, thereby allowing even more of the sun’s ultraviolet radiation to impact the retina. Even when 99% of the sun’s surface is obscured during the partial phases of an eclipse, the remaining crescent of sun is still intense enough to cause retinal burn. However, a total solar eclipse can safely be viewed with the naked eye, but only for the brief minute or two in which the sun is completely obscured by the moon.
To view the eclipse safely, you’ll need to acquire a pair of special eclipse glasses. You can check with your local science museums and astronomy clubs, they may be able to supply you with a CE certified pair of shades. Alternatively, you can purchase them online, but be careful to only get products that comply with the ISO 12312-2 international safety standard for filters for direct viewing of the sun. It’s not safe to view the eclipse with regular sunglasses.
 If using a telescope, make certain the appropriate filter is in place before pointing it at the sun.  

NASA live streaming
NASA will host an Eclipse Megacast, providing unique coverage of the astronomical event that will include commentary from scientists and the public, as well as live footage of the phenomenon. The Megacast will be broadcast on NASA TV, as well as a number of other TV stations, and can also be accessed online at www.nasa.gov/eclipselive
The next total solar eclipse viewable in North America won’t occur till 2024, so be sure to not miss out on this August’s most anticipated celestial event.