The Canadian Space Agency described the initial glimpses of the first total solar eclipse to cross the US, from Oregon to South Carolina, in 99 years as "Beautiful!" as Americans watched in wonder through telescopes, cameras and protective glasses.
US President Donald Trump watched from the Whitehouse alongside First Lady Melania while his daughter Ivanka and rock star Bruce Springsteen were among the excited big names who had tweeted advice that watchers should remember to wear their glasses when looking at the spectacle.
They saw the moon blot out the sun, cause a drop in temperature and turn daylight into twilight. It is expected to be the most observed and most photographed eclipse in history.
Totality, when the sun is completely obscured by the moon, lasted for around two minutes in each location along the narrow corridor stretching across the US heartland to Charleston, South Carolina.
Nasa Moon, NASA's official Twitter account about Earth's Moon, said: "HA HA HA I've blocked the Sun! Make way for the Moon. #SolarEclipse2017" while Hopkinsville Police in Kentucky, which saw solar enthusiasts descend on the town, tweeted "Please DO NOT call 911 just because your Wi-Fi service is not working."
Dr Francisco Diego of University College London described each eclipse is "unique", saying that it "steals your soul and it happens in complete silence".
He told BBC News: "You cannot anticipate how spectacular this is.
"You are going to be in a landscape in a normal day and suddenly in a matter of minutes in the last part of the approach, a matter of seconds, this shadow of the moon is going to cover the entire landscape and you are being plunged into darkness. You can see planets like Venus and Mercury and bright stars, there is twilight all around you and that happens so quickly. "
People were treated to the extraordinary image of what he described as a cosmic flower in the sky or the solar corona as darkness fell.
He described the diamond ring which happens at the end of the eclipse as "one of the most spectacular things to see" when the sun begins to reappear.
Gloomy skies scuppered the chances of many Britons who wanted to see a partial solareclipse on Monday evening.
The movement of the moon between the Earth and sun produced a dramatic event in the US but Britons had hoped to see the moon appear to take a "bite" out of the sun just before sunset.
Devon, Cornwall and the south coast of Dorset may have got a glimpse of the partial eclipse as about 5% of the sun was covered, according to Met Office forecaster Luke Miall.
He said: "The only place that had seen the partial eclipse was on the south coast of Weymouth which had a good show, but for the the majority of the country it was too cloudy."
Big names shared their excitement about the eclipse on social media.
Lady Gaga joked she was enjoying "Total eclipse vibes" in an Instagram photo showing her sitting on a rooftop with "Take me to your planet" written on her palms.
Former US president George HW Bush appeared in a family photograph with the message: "Four generations of family taking in the partial eclipse today. Already looking forward to the next one in Texas in 2024!"
Hollywood actresses Candice Bergen, Mary Steenburgen, Jane Fonda and Diane Keaton appeared together in an Instagram shot saying they were taking a break from book club to catch the eclipse, while model Gigi Hadid shared a message of peace in a post including the words "May the shadow of the moon fall on a world at peace".