Source- NY Times: On April 8, North America will experience its second total solar eclipse in seven years. The moon will glide over the surface of our sun, casting a shadow over a swath of Earth below. Along this path, the world will turn dark as night.
Outside the path of totality, in a vast area covering most of North America (except for a small part of Yukon and most of Alaska), Central America, and the Caribbean, as well as Greenland and Iceland, we’ll be able to observe a partial eclipse of the Sun.
Skywatchers in Mexico will be the first to see the eclipse on the mainland. From there, the show will slide north, entering the United States through Texas, then proceeding northeast before concluding for most people off the coast of Canada.
Why eclipses happen is simple: the moon comes between us and the sun. But they are also complicated. So if you’ve forgotten all of your eclipse facts, tips and how-to’s since 2017, we’re here to explain it for you.
But before we dive in, there is one thing to know that is more important than anything else: It is never safe to look directly at the sun during an eclipse (except for the few moments when the moon has fully obscured its surface). At all other times, watch the event through protective eye equipment. Read on to learn about how to watch an eclipse safely.
A solar eclipse occurs when the moon orients itself between Earth and the sun, shielding the solar surface from our view.
In cosmic terms, it is unusual that this happens: the moon is about 400 times smaller than the sun, but it is about 400 times closer to us. That means that when these two celestial bodies are aligned, they appear to be the same size in the sky.
Annular solar eclipses occur when the moon is farther from Earth and appears too small to completely shield the sun’s surface. Instead, the outer part of the solar disk remains uncovered — a “ring of fire” in the sky.
Partial solar eclipses happen when Earth, the moon and the sun are imperfectly aligned. The moon only obscures a chunk of the sun. There will be two in 2025.
Earth can also get between the moon and the sun, creating a lunar eclipse. This can be observed once or twice a year.
In any given place along the eclipse path, the event will last around two hours or more.
The event will commence with a partial solar eclipse, as the moon takes a small bite out of the sun’s edge, then consumes more and more of its surface. According to NASA, this can last anywhere from 70 to 80 minutes.
The phase of the eclipse where the moon has completely blocked the sun’s surface is called totality. This is the only time the event can be viewed with the naked eye.
The length of totality varies by location. In April, some places will experience this phase for more than four minutes; others, for only one to two minutes.
During totality, the sky will get dark as night and the temperature will drop. Wispy white strings of light from the sun’s outer atmosphere, or corona, will suddenly be visible. Lucky viewers may even spot a thin, reddish-pink circle around the edge of the moon. That’s the chromosphere, an atmospheric layer below the sun’s corona. Its color comes from the presence of hydrogen throughout the layer.
After totality, the sun will slowly peek out from behind the moon again — another partial eclipse that will last the same amount of time as the first one. The moon will recede until the sun is back to normal brightness in our sky.
In general, avoid looking directly at the sun without special equipment to protect your eyes. Inexpensive options for watching the eclipse include paper solar viewers and glasses. If you are using equipment purchased for a past solar eclipse, make sure to inspect it. Toss anything with scratches or other signs of damage.
According to NASA, it is not safe to look at the sun through any optical device while using paper glasses or viewers. To watch the eclipse through cameras, binoculars or telescopes, buy a special solar filter.
The only time you can view a solar eclipse with the naked eye is during the moments of totality. Once the moon begins to reveal the surface of the sun again, return to watching the event through protective equipment to avoid injury.
