On Tuesday, a total solar eclipse will stretch across South America. The path of totality, where the moon visibly blocks the sun, will span parts of Chile and Argentina. Outside the path of totality, a partial solar eclipse will be visible.
The umbral shadow -- the area in which the sun will appear completely covered by the moon -- will pass over the Pacific Ocean, Chile and Argentina, according to NASA.
Depending on where you are, the spectacle could last up to four minutes and three seconds, the space agency said.
The total solar eclipse will appear in the sky over the city of La Serena, Chile, at 4.38 p.m. ET and travel across the Andes mountain range before ending near Buenos Aires, Argentina, at 4.44 p.m. ET.
To see "totality," in which the moon completely blocks the sun, you will need to be inside the narrow swath -- about 90 miles wide -- of the moon's shadow. But weather may be the next biggest obstacle for those within the path of totality. Cloudy skies could block the view of the total solar eclipse.
Outside of this path, a partial solar eclipse will be visible in Argentina and Chile, as well as Ecuador, Peru, Bolivia, Paraguay, Uruguay and parts of Colombia, Brazil, Venezuela and Panama, according to NASA.
"The July 2nd eclipse is the first total solar eclipse since the transcontinental total solar eclipse in summer of 2017," said Paige Godfrey in a statement, astrophysicist at the Slooh Community Observatory which has a location in Chile."That was almost two years ago now, and people are still talking about it as the greatest celestial event of their lifetimes. That event has had a lasting effect that has heightened excitement for many of these to come."
But this eclipse won't be easy to spot as the 2017 eclipse, which moved diagonally from west to east across North America.
"The 2019 South American solar eclipse is not an easy event to capture," said Paul Cox, Slooh's chief astronomical officer. "Unlike the 2017 eclipse, and except for a tiny uninhabited South Pacific island, the path of totality -- the 90-mile wide path of the Moon's umbral shadow -- only makes landfall across a narrow stretch of Chile and Argentina. Having raced across the Pacific Ocean at over 6,000 mph, by the time the Moon's shadow reaches the west coast of Chile, the Sun will be low to the horizon, with the partial eclipse phases occurring just as the Sun is setting."
If you can't watch the eclipse from your location, there are several options to watch online. NASA is partnering with Exploratorium in San Francisco to present live views from Chile between 3 and 6 p.m. ET. Slooh will share a live stream between 3:15 p.m. and 5:50 p.m. ET. The European Southern Observatory , based in Chile, will also share a live view.
If you miss Tuesday's eclipse and you're eclipse chaser who doesn't mind globetrotting, you can also catch these total solar eclipses around the world in the coming years:
- 2020: South Pacific, Chile, Argentina, South Atlantic
- 2021: Antarctica
- 2024: North America
- 2026: the Arctic, Greenland, Iceland, Spain
- 2027: Morocco, Spain, Algeria, Libya, Egypt, Saudi Arabia, Yemen, Somalia
- 2028: Australia, New Zealand
- 2030: Botswana, South Africa, Australia
How to safely watch the eclipse
Wherever you are in the path of the eclipse, you're going to want to look up, and that's OK. Every astronomer will tell you to enjoy this rare opportunity. No matter what superstitions you've heard, there is no risk to your health due to simply being outside during a total solar eclipse.
But there's one thing you shouldn't do, and that's look at the sun with your naked eye.
Don't do it. Really.
The only time you can look at the sun with your naked eye is A) if you're in the path of totality, where the sun will be completely covered by the moon, and B) during those two minutes or less when the sun is completely covered.
During those brief and geographically constrained moments, the brightness of the sun is reduced to that of a full moon, which can be viewed safely without anything over your eyes.
Otherwise, any glimpse of the sun's brightness is not only uncomfortable, it's dangerous.
Looking directly at the powerful brightness of the sun can cause damage to the retina, the light-sensitive part of the eye.
"When you look directly at the sun, the intensity of the light and the focus of the light is so great on the retina that it can cook it," said Dr. Christopher Quinn, president of the American Optometric Association. "If the exposure is great enough, that can and will lead to permanent reduction in vision and even blindness."
The retina may translate light into an electrical impulse that the brain understands, but one thing it can't translate to your brain is pain. So even if you're excited about the eclipse and think one brief glimpse at the sun before it completely hides behind the moon is worth it -- it's not. There's no internal trigger that is going to let you know that you've looked at the sun for too long. Any amount of looking at it is too long.
Even the smallest amount of exposure can cause blurry vision or temporary blindness. The problem is, you won't know whether it's temporary.
"It's really impossible for people, when they're in the moment, to make a judgment over brief versus prolonged exposure," Quinn said. "It's never a good idea to view the eclipse without the protection."
When the total solar eclipse happened across America in 2017, a young woman sustained permanent eye damage from viewing the eclipse without proper eye protection.
No matter how cute or fancy they may be, wearing your favorite pair of sunglasses -- or a whole stack of sunglasses, for any MacGyver wannabes out there -- won't help. You'll need eclipse glasses, which are regulated by an international safety standard.
Astronomers Without Borders sent recycled eclipse glasses from around the US to different schools, astronomy clubs and organizations in South America.