The Discovery of Neptune

Discoveries in science happen in very different ways. No two stories of discoveries are the same. Today, let us learn about the interesting story behind the discovery of Neptune.

Neptune was first discovered theoretically. Its existence was predicted by the mathematician Urbain Le Verrier, and his results were sent to the Berlin Observatory on September 23, 1846. Actually, two scientists can be credited with the discovery, namely Le Verrier, and the British John Couch Adams of Cambridge. 

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Neptune (Credits: NASA)

Early observation

Neptune has been observed many times before 1846, but it was always overlooked. John Herschel almost discovered it the same way his father, William Herschel, discovered Uranus. Still, it was not regarded as a planet. It was all the times mistook with a star. 

Indeed, there is evidence to show that Galileo identified something strange about the blue dot in the sky. He was aware of the fact that he had discovered something unusual about ”Neptune”, but didn’t have enough data to continue the research on the subject, and so he never came back to the problem again.

Also Read: All the articles of Basics of Astrophysics series

Coming closer 

The planet’s existence began to be considered around 1800. Observations of Uranus’ orbit made astronomers hypothesizing some perturbing body. Another planet should have been there. 

One of the first to study the irregularities in Uranus’ orbit was John Adams, who was an undergraduate when he first learned about them. After finishing his degree, he got elected as a fellow of his college, and he started studying the problem the problem deeply. By September 1845, he completed a lot of calculations. Still, they were not recognized at their real value, and his conclusions were doubted. 

Urbain Le Verrier, unaware of Adams’ research, began one of his own, concluding with the presentation of his work at the Academy of Sciences, on November 10th, 1945. His work sparked interest to the British scientists, who immediately recognized the similarity between Adams’ and Le Verrier’s studies. Adams’ work, previously seen as a scientific “curiosity”, was now declared an “urgent” subject for observation. 

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Le Verrier (Credits: PBS)

The day we saw Neptune (or realized it was Neptune)

As Le Verrier couldn’t get the attention of the French scientists, he sent his results to the Berlin Observatory. Johann Gottfried Galle, a scientist from Berlin, received Le Verrier’s letter on 23 September, and immediately set to work on the problem. 

The discovery came very fast. Just after midnight, on September 24, Galle saw Neptune, following Le Verrier’s calculations.

The thing is, we can't credit either Le Verrier, or Galle, or Adams with the discovery of Neptune. First, because neither of them really saw it first, and second, because Le Verrier and Adams both have succeeded in calculating the position of Neptune, proving its existence.

Also Read: The difference between Astronomy, Astrophysics and Cosmology.

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