When was the crucifixion? A little eclipse science can help

Whether you’re a Christian recognising Easter this month, or simply enjoying time with friends, family and chocolate, you’ve probably come across one particular part of the Easter story – the crucifixion.

Pick up a copy of the Bible and you’ll come across passages that describe a time when the sun stops shining for several hours after Christ’s crucifixion.

Scientists and historians have long suggested this could be a reference to a historic eclipse.

Finding potential candidates for this event is certainly possible, after more than 5,000 years of solar and lunar eclipses having been calculated by NASA astrophysicist Fred Espenak and astronomer Jean Meeus.

Solar or lunar

A solar eclipse occurs when the Moon passes between the Earth and Sun, casting a shadow on part of the Earth.

A total solar eclipse occurs when the Moon completely blocks out the sun. A similar event is an annular eclipse. Like a total eclipse, annulars occur when the three bodies line up, but due to the Moon being at its farthest point, ground viewers will witness a ‘ring of fire’.

A lunar eclipse, on the other hand, occurs when the Earth moves between the Moon and Sun. This results in the Earth casting a shadow across our rocky satellite. A total lunar eclipse often appears as though the Moon has turned red, due to longer wavelengths of light from the sun passing through our atmosphere and creating a ‘blood moon’ effect. Partial eclipses appear to cast the Moon in a temporary shadow.

Supermoon stage
Phases of a supermoon lunar eclipse. Credit: NASA/Rami Daud

Aligning the heavens with eyewitness accounts

In the present day, astronomers consider the interactions between the gravity of the Earth, Sun and Moon, and the geometry of where each is positioned. This information is fed into computer systems that can be programmed to calculate their positions in space forward and backward in time.

Because of this, it’s possible to know exactly where and when a solar or lunar eclipse will take place centuries into the future, and how they occurred in years past.

It also makes it possible to align historic accounts of eclipses to these precise calculations to land on when particular events might have occurred.

Two descriptions of celestial phenomena around the crucifixion will be familiar to those who commemorate Easter for its religious significance: either the sky turning dark as described in the gospels – potentially a solar eclipse – or of a blood moon consistent with a lunar eclipse described in subsequent books.

And three eclipses could line-up with this event.

Bible scholars often point to April 3, CE33 as the crucifixion date, based on calculations for when a full moon associated with the Jewish Passover feast might have fallen and interpretations of accounts in the gospels.

That falls in line with a lunar eclipse that would have been witnessed by inhabitants in modern-day North America, and between central Europe, East Africa, Asia – including Israel – and the Pacific. In 2011, A Cambridge University physicist and hobbyist Bible scholar published a book which reconciled this event to the date in CE33.

What about solar eclipses?

The most likely solar eclipse candidate in CE33 would have only been partly visible from the east and south coasts of Africa, parts of modern-day India, Sri Lanka and Indonesia, and fully visible to penguins in Antarctica, whereas in 29CE, folks living in Jerusalem and neighbouring countries would have witnessed a partial eclipse.

The last glimmer of the sun is seen as the moon makes its final move over the sun during the total solar eclipse on monday
The last glimmer of the sun is seen as the moon makes its final move over the sun during the total solar eclipse on Monday, August 21, 2017 above Madras, Oregon. Credit: NASA/Aubrey Gemignani

Five millennia of eclipse records

Combining astronomy, history and archaeology, Espenak has gone about listing numerous solar and lunar eclipses which might correspond to phenomena listed in ancient documents and historical texts from the time of Homer’s Odyssey to the present day (though it’s worth noting, this doesn’t validate any of the claims made in the texts).

The trajectory of these events can be viewed using online mapping services. One such tool was developed by French engineer and member of the International Astronomical Union’s working group on solar eclipses, Xavier Jubier.

What you need to get ready for the upcoming solar eclipse and other celestial wonders

Utilising the 5,000-year database, Jubier’s tool allows eclipse enthusiasts to track the path of eclipses as they would be witnessed on the ground at key points in history.

This includes upcoming solar eclipses observable from Australia and South-East Asia in April, and across the Americas in October this year.

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