The Great American Eclipse (2017)
On 21 August 2017 the Moon’s shadow crossed the United States from coast to coast for the first time in 99 years.
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The story
On 21 August 2017 the shadow of a total solar eclipse touched the coast of Oregon and, about ninety minutes later, left the United States over South Carolina. It was the first time since 1918, 99 years earlier, that the Moon’s shadow had crossed the country from coast to coast, so people called it the Great American Eclipse. The strip where the Sun was fully covered was about 110 km wide, and totality lasted longest near Carbondale, Illinois, at 2 minutes 41 seconds.
It was also an eclipse shared by an enormous number of people. A University of Michigan survey found that 88 percent of American adults watched it, either in person or on a screen. About twelve million people lived inside the path of totality, and millions more travelled into it. The largest city in the path was Nashville, Tennessee, where daytime turned dark as night for about two minutes.
For scientists the day was just as special. The Sun’s activity was winding down at the time, so the corona, the Sun’s outer atmosphere that can only be seen during totality, stretched out mainly along the Sun’s equator. A citizen-science project called Citizen CATE set up 68 telescopes along the path. As the shadow left one site, the next telescope took over, and together they recorded the corona without a break for about ninety minutes.
The interest sparked that day carried over to the total eclipse of 8 April 2024, seven years later. The idea of small towns and national parks welcoming eclipse visitors with festivals also spread widely from 2017. Choosing this eclipse in the sky view replays the two-minute scene over Nashville, with the Sun turned black and the corona showing around it.
Viewing guide — where, when, how
Choose the 2017 eclipse in the sky view’s event list to replay totality over Nashville at about 1:27 pm local time on 21 August. Beside the black Sun, high in the sky, the star Regulus appears very close, with Venus and Jupiter a little farther away. Move the location to Madras, Oregon, or Carbondale, Illinois, and the time and length of totality change.
This eclipse belongs to the family called Saros 145. A saros is a cycle of about eighteen years after which a similar eclipse comes around again. The previous member was the European eclipse of 11 August 1999, and the next is the total eclipse of 2 September 2035 over China, northern Korea and Japan. The orbit view’s event replay shows the Moon’s shadow crossing North America from west to east. The next US total eclipse is on 23 August 2044, and on 12 August 2045 another path crosses the whole continent.
See this for yourself — open that sky at that moment · replay the moment in the orbit view
Why this eclipse is special
The 2017 eclipse is remembered as one in which ordinary people took a big part in science. Besides Citizen CATE, huge numbers of people recorded how much the temperature fell and how animals behaved, and sent in their notes. That experience helped shape the even larger citizen-science plans for the 2024 eclipse.
It was also an important test for the power grid, the network that delivers electricity. By then solar power had grown noticeably in the United States, and when the Moon covers the Sun, solar output drops sharply within minutes. Operators in places with a lot of solar power, such as California, lined up other power plants in advance, and the eclipse passed without major blackouts.
It was the first total eclipse visible from the US mainland since 1979, a gap of 38 years, so for many Americans it was the first they had ever seen. The path of the 2024 eclipse later crossed the 2017 path near Carbondale in southern Illinois, which gave people there two total eclipses only seven years apart.
Background and earlier eclipses
The previous total eclipse to cross the United States from coast to coast was on 8 June 1918. The eclipse of 26 February 1979 touched only the north-west, including Washington, Oregon, Idaho, Montana and North Dakota, and the eclipse of 11 July 1991 crossed Hawaii but missed the mainland.
The shadow’s speed changed along the way. When it reached Oregon it was moving at about 3,900 km/h, but over South Carolina it had slowed to about 2,400 km/h. Earth also spins toward the east, the same way the shadow was moving, so the shadow’s speed across the ground dropped. A slower shadow takes longer to pass any one place, which is why totality grew from about two minutes on the west coast to 2 minutes 41 seconds in the middle of the country.
Observations also came from the air and from space. Astronauts on the International Space Station photographed the Moon’s shadow moving across Earth. Two NASA WB-57 research jets chased the shadow above the clouds and watched the corona for longer than anyone standing in one place on the ground. Meanwhile, after the eclipse, roads in states such as Oregon and Wyoming were jammed with people heading home.
FAQ
How long did totality last?
The longest was 2 minutes 41 seconds near Carbondale, Illinois; in Nashville it lasted about 1 minute 54 seconds.
Why is it called the Great American Eclipse?
It was the first coast-to-coast crossing of the United States in 99 years, and 88 percent of American adults watched it in person or on a screen.
How was it different from the 2024 eclipse?
In 2017 the Sun was growing quieter, so the corona stretched along the equator; in 2024 it was very active and the corona spread in all directions. Totality was also longer in 2024.
When is the next US total eclipse?
On 23 August 2044 over Montana and North Dakota, followed by a coast-to-coast crossing on 12 August 2045; the weather on those days cannot yet be known.
Related
- Total eclipse — across Europe (1999)
- Total solar eclipse of September 2035
- Total eclipse — longest of the century
- The Sun — object index
- The Moon — object index
Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.