In 2018, skywatchers in a few select locations on Earth will have three opportunities to see a solar eclipse, a celestial event in which the moon briefly appears to take a bite out of the sun.
A solar eclipse occurs when the disk of the moon appears to cross in front of the disk of the sun. A total solar eclipse — like the one that took place on Aug. 21, 2017 — occurs when the disk of the moon blocks 100 percent of the solar disk. A partial eclipse occurs when the moon covers only part of the sun.
Only partial eclipses will occur in 2018. The first solar eclipse of 2018 took place on Feb. 15 and was visible only from parts of Antarctica, the Atlantic Ocean and southern South America. The second partial eclipse of 2018 will take place on July 13 and will be visible primarily over the ocean between Australia and Antarctica. The third solar eclipse of the year will take place on Aug. 11 and will swing over the North Pole. It will be visible from northern Europe, northern Asia and parts of eastern Asia. [Solar Eclipses: An Observer's Guide (Infographic)]
You can see a complete list of the upcoming solar eclipses on NASA's website, which provides information about solar eclipses, including detailed maps of each eclipse path.
Partial solar eclipse coming July 13
The partial solar eclipse of July 13, 2018, will take place almost entirely over open water. Because the eclipse will arrive during the Southern Hemisphere's winter, most of Antarctica will be experiencing "polar nights." During these periods, the sun does not rise for days, weeks or months at a time. But the partial solar eclipse will briefly pass over the illuminated edge of the continent that lies just south of Australia. Skywatchers on the very southern coasts of Australia and New Zealand might catch brief views of the eclipse.
This partial eclipse will begin at 9:48 p.m. EDT on July 13 (0148 GMT on July 12), reaching its maximum magnitude of 0.3367 at 11:01 p.m. EDT (0301 GMT). Eclipse magnitude is what fraction of the sun's diameter is covered by the moon.
In a partial eclipse, the center of the moon's shadow "misses" the Earth — this is why there's no region of totality. As a result, a quirk of partial eclipses is that the sun is closest to the horizon at the point of the greatest eclipse. This is also why the areas where you can see a partial eclipse occur tend to be near the poles. The phenomenon differs from the partial solar eclipses visible from areas outside the zone of totality, when total solar eclipses occur somewhere on Earth — for example, during the August 2017 eclipse — because, in this case, there is no point where the center of the moon's shadow touches the Earth at all.
Another partial solar eclipse on Aug. 11
The eclipse will start out over the North Atlantic Ocean and Greenland, moving north and east so that the shadow simultaneously moves toward Iceland, northern Europe and the northern polar regions. Continuing its path over the top of the planet, the shadow will be wide enough to cover most of northern Russia from east to west. It will then dip down into Mongolia, China and surrounding areas.
It will officially begin when the moon first appears to make contact with the sun's disk at 4:02 a.m. EDT (0802 GMT). Maximum eclipse will happen at 5:46 a.m. EDT (0946 GMT), when the eclipse is at magnitude 0.7361.
Partial solar eclipse of Feb. 15
The partial solar eclipse of Feb. 15, 2018, began over Antarctica and the surrounding ocean. It moved up and over South America, including Argentina and Chile, with some visibility as far north as Uruguay, Paraguay and Brazil. This animation shows the eclipse's full path.
The February eclipse had a magnitude of 0.599 at its maximum. The point of maximum eclipse — where observers could see the most coverage of the face of the sun — was on the coast of Antarctica, east of the Antarctic Peninsula, where the nearest inhabited areas are research bases.
More accessible was South America, another region of partial eclipse visibility. The farther south you go, the larger the covered portion of the sun was. Observers in Montevideo, Uruguay, for example, could see an eclipse of magnitude 0.181, with a maximum of 8.8 percent of the sun's face covered, according to timeanddate.com. Uruguayans saw the moon touch the sun's edge at 6:34 p.m. local time, and the eclipse reached its maximum at 7:11 p.m.
In Buenos Aires, the eclipse was at magnitude 0.166, with a coverage of about 7.7 percent. The eclipse will start at 6:36 p.m. local time and will reach a maximum at 7:12 p.m. Here, too, the sun set at 7:46 p.m., before the eclipse was over.
To see the whole eclipse before sunset, you have to go farther south; one of the larger cities in the southern reaches of Argentina is Río Gallegos, which will see 22 percent of the sun covered. The eclipse will begin at 5:45 p.m. local time, will reach maximum at 6:41 p.m. and will end at 7:33 p.m.
More adventurous or determined eclipse chasers could go to Stanley, a town in the Falkland Islands, where a magnitude 0.398 eclipse occurred, meaning 28 percent of the sun was obscured by the moon. Falkland Islanders saw the eclipse start at 5:46 p.m. local time and reach maximum at 6:42 p.m. before the eclipse ended at 7:34 p.m.
Other kinds of solar eclipses
In addition to total and partial solar eclipses, skywatchers may want to try to see an annular eclipse, which occurs when the moon passes over the center of the sun's face but a sliver of the sun's disk remains visible. That sliver creates a bright ring around the moon, which is why an annular eclipse is also known as a "ring of fire" eclipse. The next annular eclipse will occur on Dec. 26, 2019, and will be visible in Saudi Arabia, India, Sumatra and Borneo.
No total solar eclipses will take place in 2018. The next total solar eclipse will occur on July 2, 2019, and will be visible in the South Pacific, Chile and Argentina.
Both annular and total eclipses occur, on average, every 18 months.
How to view the sun safely
WARNING: Looking directly at the sun, even during an annular eclipse, can lead to blindness and other forms of permanent eye damage if you aren't wearing proper eye protection.
To safely observe the sun or watch an eclipse, you need special protective eyewear or eclipse glasses. Basic sunglasses, even those with UV protection, will not sufficiently protect your eyes. If you're planning to document the eclipse with any photo equipment, there are special solar filters you can add to make sure the remaining ring of sunlight doesn't take a toll on your vision.
The safest way to observe an eclipse is indirectly, using a pinhole camera that you can make easily at home.
If you must document one of these events, a simple, wide-angle snap should capture the moment, even if you're using your smartphone camera.