What was the first thing scientists discovered? A historian makes the case for Babylonian astronomy

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What was the first thing scientists discovered? – Jacob, age 9, Santiago, Panama

All societies have had ways of understanding nature based on their experiences of it. For example, farmers need to understand the seasons and weather to know when to plant and harvest their crops. Hunters need to understand the lives of animals to know how to hunt them.

This kind of understanding of the natural world isn’t quite the same as science though. Science typically refers to knowledge that’s more organized and formal than that. It’s not just an explanation, but a system that uses observations and experiments to build theories that are recorded, passed on to others and built on.

With that idea in mind, as a historian of science, my best answer to the question of what the first scientists discovered is Babylonian astronomy.

The Babylonians lived from about 2,500 to 4,000 years ago in the area that’s now Iraq. What makes Babylonian astronomy stand out as being especially scientific is the careful, organized way in which Babylonian scribes – their keepers of knowledge – observed, recorded and eventually mathematically predicted the ways that the Sun, Moon, stars and planets move in the skies.

Babylonian astronomy was uniquely scientific

Before clocks, observing the sky was how people knew the time. During the day you can see the Sun, and at night you can see the stars. Many calendars are based on the skies too. A month is about how long it takes the Moon to go through its phases. A year is one full revolution of the Earth around the Sun.

But keeping track of time wasn’t the only way the Babylonians used astronomy. Like today’s world, Babylonia could be both predictable and chaotic. The weather changed with the seasons; crops were planted and harvested; festivals were celebrated; people were born, aged and died, all predictably. But a bad harvest might cause high prices for grains and starvation; a king might die young, causing political upheaval; a disease might kill thousands, all unpredictably.

The stars and planets can seem like that, too. The stars are always in the same places in relation to one another, so you can identify constellations, and those constellations rise and set at regular times over the course of a year. But the planets move around – they’re not always in the same places, and sometimes they even seem to stop and move backward in their paths. Sometimes even more spectacular events occur, such as eclipses.

For the Babylonians, those ideas were linked. They saw changes in the motions of the planets or rare events such as eclipses as signs – omens – about what was going to happen on Earth. For example, they might think the shadow of the Earth moving over the Moon in a certain way during a lunar eclipse meant that a flood would also happen.

The scribes kept a book called Enūma Anu Enlil listing omens and their meanings. So if the seemingly changing motions of the heavens could be predicted, maybe earthly events could be, too. This led the scribes to study astronomy.

How Babylonian astronomy worked

The foundation of Babylonian astronomy was kept in a book called MUL.APIN, meaning “The Plough Star,” the name of a constellation. It recorded the positions of the stars, when in the year they would first be visible, the paths of the Sun and Moon, the periods when the planets would be visible in the night sky, and other fundamental astronomical knowledge.

Later, Babylonian scribes began to keep their Astronomical Diaries, which contained detailed records of the positions of the Moon and planets along with events on Earth such as the weather and the price of grain. In other words, they recorded their observations of both astronomical omens and the events they might have predicted.

This kind of careful observation and record-keeping is a major part of science. The Astronomical Diaries were kept for over 700 years, making them maybe the longest-running scientific project ever.

The records in the Astronomical Diaries helped Babylonian scribes take another scientific step: predicting astronomical events. One part of this was computing what the Babylonians called goal-years: the number of years it took for a planet to return to the same place on the same day. For example, they computed that the period for Venus was eight Babylonian years. So if Venus was somewhere on a particular day, it would be in the same place on the same day eight years later.

By around the fourth century B.C.E., the scribes developed this knowledge into a system of mathematically predicting astronomical events. They made tables called ephemerides that showed when these events would happen in the future. So Babylonian scribes succeeded in their project: They made the motions of the Sun, Moon and planets predictable.

Babylonian astronomy and you

MUL.APIN, the Astronomical Diaries, the ephemerides and all of Babylonian astronomy had a major impact on later astronomers, one that continues to today. Greek astronomers used Babylonian observations to make geometric models of planetary motions, part of the long path toward modern astronomy. The ephemerides were the ancestors of astronomical tables, which still exist. For example, NASA has a table of eclipses online that goes to the year 3000.

But the most familiar thing that comes from Babylonian astronomy is how we tell time. The Babylonians didn’t use a decimal system with units of 10 like we do. Instead, they used a sexagesimal system, with units of 60. Babylonian observations were so important that later people kept Babylonian units for astronomy, even though they used a base 10 system for other things.

So if you’ve ever wondered why an hour has 60 minutes, and a minute has 60 seconds, it’s because we’ve kept that way of measuring from Babylonian astronomy. Whenever you tell the time, you’re using some of the very oldest science.

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This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: James Byrne, University of Colorado Boulder

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James Byrne does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.