A total solar eclipse has plunged parts of Mexico into darkness.
At the point of totality, the Moon perfectly blocks the Sun.
It lasts for about four minutes.
Crowds are gathered across North American cities that lie in the path of the eclipse.
It will sweep north and east across 13 US states and finish in Canada.
This event is rare as it will cover several densely populated cities, with some 31.5m people able to see it, Nasa says.
The space agency will be conducting experiments, flying planes and rockets to study the Sun's atmosphere.
To enjoy the phenomenon safely, never look at the Sun with the naked eye, even with sunglasses on - wear solar eclipse glasses.
“I’ve been waiting for this for 12 years,” Cesar Picazo says.
“Ever since I found out it would be happening here.”