The Sun and Moon look the same size by coincidence
The Sun is about 400 times wider than the Moon and about 400 times farther away, so both appear about half a degree across in our sky.
Total eclipses will eventually stop
The Moon drifts away from the Earth by about 3.8 cm a year. NASA estimates that in roughly 650 million years it will look too small to cover the Sun completely.
There is a total eclipse somewhere about every 17 months
In the century from 1926 to 2025 we count 72 total solar eclipses, an average of one every 17 months. Most paths cross oceans or remote land, which is why they feel so rare.
The longest totality of the last century lasted just over seven minutes
It happened on 20 June 1955, with the path crossing Sri Lanka, India, Myanmar, Thailand, Cambodia, Laos, Vietnam, Philippines. No total eclipse can last much more than about seven and a half minutes at a fixed spot on the ground, and the 2027 eclipse, at a little over six minutes, is the longest over land this century.
Concorde stretched totality to 74 minutes
On 30 June 1973, Concorde 001 took off from Las Palmas in the Canary Islands and flew under the Moon’s shadow at twice the speed of sound, keeping a team of astronomers in totality for 74 minutes before landing in Chad.
Some years have 5 solar eclipses
Every year has at least two solar eclipses. In our catalogue from 1926 to 2035, 1935 has 5, the most possible in one calendar year.
One path crossed 17 countries
The path of the total eclipse of 20 May 1947 crossed 17 countries, from Chile to Tanzania. By our calculation, no total eclipse between 1926 and 2035 crossed more.
The 2027 eclipse is the 2009 eclipse coming back
Eclipses repeat every 18 years, 11 days and 8 hours, a cycle called the saros. The total eclipse of 2 August 2027 is the next in the same series as the long eclipse of 22 July 2009 over India and China.
Cairo is outside the 2027 path
Many travel articles say the 2027 eclipse is total over the pyramids. It is not: Cairo sees a partial eclipse with about 94.8% of the Sun covered, while Luxor, about 500 km to the south, gets 6m 25s of totality.
The corona is hotter than the Sun’s surface
The visible surface of the Sun is about 5,500°C, but the corona seen during totality is over a million degrees. Why it is so hot is still one of the big open questions in solar physics.
Helium was found in the Sun before it was found on Earth
A bright yellow line seen in the Sun’s spectrum during the eclipse of 18 August 1868 led to the discovery of helium, named after the Greek word for the Sun. It was isolated on Earth in 1895.
An eclipse helped prove Einstein right
Star positions photographed during the total eclipse of 29 May 1919, from Príncipe and from Sobral in Brazil, showed starlight bending around the Sun as general relativity predicted. The results were announced on 6 November 1919.
The first photo of totality took 84 seconds
Johann Julius Friedrich Berkowski made the first successful photograph of a total eclipse on 28 July 1851 in Königsberg, using a daguerreotype exposed for 84 seconds.
An eclipse may have stopped a war
Herodotus wrote that a battle between the Lydians and the Medes stopped when day suddenly turned to night, and the two sides made peace. The eclipse of 28 May 585 BCE is the usual match, though historians debate the story.
Solar and lunar eclipses come in pairs
Both kinds need the Sun, Earth and Moon to line up near the Moon’s nodes, so a solar eclipse is often followed or preceded by a lunar eclipse about two weeks apart, in the same eclipse season.
Annular eclipses never get dark
Even at the peak of a ring of fire, the remaining sliver of Sun keeps the sky bright, and you need eclipse glasses throughout. Only totality is safe to view with the naked eye.