• Germany's news in English
 
app_header_v3

The German astronomer who found Neptune

The Local · 25 Sep 2015, 16:00

Published: 25 Sep 2015 16:00 GMT+02:00

On the night of September 23rd 1846, an astronomer and his assistant were hard at work at the Berlin Observatory.

Earlier that day, Observatory director Johann Franz Encke had received a letter from French mathematician Urbain le Verrier. 

Le Verrier was convinced that there was an eighth planet in the solar system. Something was amiss with Uranus' orbit - and the previous year, le Verrier had proven that no current theories explained the orbit's irregularities.

Something was interfering with Uranus' orbit, le Verrier concluded – and this something was a planet.

By June he had predicted this planet's location, and on 31st August he presented a memoir to the Académie des Sciences in Paris, detailing the predicted mass and orbit of the planet.

Frustratingly, le Verrier couldn't convince any French astronomers to take up the search for his mystery planet. So he sent his findings to Encke, at the Berlin Observatory. 

Encke received the letter on September 23rd. But he had a problem: he was double booked.

The Wilhelm Förster Observatory and Planetarium in Berlin. Photo: Wikipedia.

The night of the discovery

Susanne M. Hoffmann is an astronomer at Wilhelm Förster Observatory and Planetarium in Berlin, and director of the planetarium's Astronomical History research committee.

It was Encke's birthday on September 23rd,  she told The Local - and on that evening in 1846, he had to throw a party for numerous important people across Berlin.

Unable to get out of his own birthday party, Encke was forced to pass the job on to his assistant Galle.

"He couldn't do it himself, but he wanted someone at his observatory to do it," Hoffmann explained.

Encke was more of a mathematician than an observer, Hoffmann said - and this was perhaps the reason he was so comfortable letting Galle take the telescope that evening.

"We don't know for sure, but it seems Encke wasn't so interested in making the observations himself," she said.

Johann Gottfried Galle had worked as Encke's assistant since 1835. Born in Radis, in Saxony-Anhalt, he studied at the Friedrich-Wilhelms-Universität Berlin from 1830 to 1833, then taught maths and physics before the Berlin Observatory's opening in 1935.

After receiving his orders from Encke, Galle set to work straight away, assisted by Berlin University student Heinrich Louis d'Arrest.

Le Verrier had given instructions as to where Neptune should be – and as fortune would have it, astronomers at the Berlin Observatory had recently made charts of that very area of sky.

When d'Arrest suggested the pair get out these charts and compare them with the sky to seek an orbiting planet, it didn't take Galle long at all to hunt Neptune down.

"Galle knew every dot in that area," Hoffmann explained, "and he knew this dot didn't belong in the position it was in."

It was past 11pm by the time Galle began his hunt for the planet – and shortly after midnight on the morning of September 24th, he'd found that dot that didn't fit the charts.

In under an hour, Galle had found an orbiting planet among the stationary stars - less than one degree from where le Verrier had predicted it would be.

Image: NASA

Who really discovered Neptune?

In the aftermath of Neptune's discovery, arguments broke out as to who truly "found" the planet.

Le Verrier wasn't the only person who had predicted Neptune's existence - in 1845, Cambridge astronomer John Couch Adams also set out to calculate the nature and position of the planet which was disrupting Uranus' orbit.

The two astronomers worked entirely separately, unaware of each other's efforts.

At first, Adams' predictions were treated as a curiosity, but when British Astronomer Royal George Airy received news of la Verrier's predictions, he realised the two astronomers were probably hunting down the same planet.

James Challis, director of the Cambridge Observatory, was tasked with finding Neptune before la Verrier.

The British search for Neptune began on July 29th – and only after the Berlin discovery on September 23rd did Challis realise that he had actually spotted Neptune already.

Challis had allegedly observed the planet on August 8th and 12th, but because he lacked an up-to-date star map, he hadn't recognised Neptune as a planet.

Despite bitter arguments between the two countries, Adams himself publicly acknowledged the French astronomer's credit in finding the planet.

A first in the history of science

But where did Galle fit into all of this?

Story continues below…

"Le Verrier was the calculator who made the right assumption, while Galle was the one pointing the telescope," said Hoffmann.

Galle's job wasn't easy, either. "It was a masterpiece, identifying the little dot that was Neptune," she explained.

But le Verrier's remarkable calculations made the discovery on September 24th a true first.

"This was the first time - not just in the history of astronomy but in the history of all science - that something in nature was predicted this accurately," Hoffmann said. "Nobody knew that Neptune was really there"

The discovery was also a testament to Berlin's leading astronomical research facilities.

"Berlin was the centre of astronomical observations at the time," Hoffmann said.

"It was the best observatory in Europe, maybe even the world," she said, adding "all people turned to Berlin when they wanted observations."

And the fact that Berlin astronomers had recently charted out that very area of sky was a definite advantage.

"It was the right time and the right place," Hoffmann concluded.

By Hannah Butler

 

 

For more news from Germany, join us on Facebook and Twitter.

The Local (news@thelocal.de)

Your comments about this article

Today's headlines
Far-right AfD leader injured by flying frozen cake
Jörg Meuthen and a cake. Photo: DPA

The co-leader of the far-right AfD party was attacked with a cake while attending a political event on Monday. But the fact the dessert was frozen made the act "dangerous", according to the politician.

Underwater pensioner hunts boats on famed Bavarian lake
A passenger boat on Lake Starnberg. Photo: DPA

"I love chasing the ships, and what a great feeling it is when they sound the horn!" he gleefully exclaims.

What are Merkel's chances for remaining Chancellor?
Photo: DPA.

She's already held the Chancellery for over a decade, but infighting with political allies as well as a rocky response to her refugee policies may put a damper on Angela Merkel's staying power.

German EU commissioner doubts Brexit will happen
EU Energy Commissioner Günther Oettinger. Photo: EPA.

Germany's EU Commissioner Günther Oettinger raised doubts on Tuesday about whether Britain would leave the bloc, saying he wouldn't bet on "Brexit".

Merkel offers Russia a lifting of sanctions - if it behaves
Angela Merkel. Photo: DPA

Chancellor Angela Merkel said on Monday that she has "the very greatest interest in stopping sanctions" against Russia, Reuters reports.

'Idiot' youth lets regional train drive over him as dare
Photo: DPA

In a stunt police have described as "incomprehensible idiocy," a drunk young man from Munich lay down on the tracks in front of a fast-moving train and let it ride over him.

'Unfriendly' Germans make expat life harder: report
Photo: Pexels.com

Expats in Germany generally find it great for families and starting a career, but were turned off by the language barriers and "unfriendly" Germans upon arrival, according to a new report.

Is German diplomacy getting too chummy with Russia?
Russian President Vladimir Putin meeting German Foreign Minister Frank-Walter Steinmeier. Photo: DPA/AFP Pool.

Critics have been questioning the German Foreign Minister's recent series of comments about working closer with Russia, with some labelling the diplomat a "Russia-sympathizer".

Police investigate after mosque door is bricked shut
The bricked-up door. Photo: Facebook/Netzwerk für Flüchtlinge in Parchim.

Unknown people have bricked up the entrance to a mosque in northeastern Germany and stuck racist flyers to their masonry work.

Vice-Chancellor: TTIP trade deal is dead
Photo: DPA

Vice-Chancellor Sigmar Gabriel said on Sunday that negotiations on a massive trade deal between the European Union and the United States were effectively dead in the water.

Sponsored Article
Why you should attend an international job fair
National
Ouch! Naked swimmer hospitalized after angler hooks his penis
Sponsored Article
Why expats choose international health insurance
National
Six reasons why Berlin is now known as 'the failed city'
National
15 tell-tale signs you’ll never quite master German
Sponsored Article
Why you should attend an international job fair
Culture
7 American habits that make Germans very, very uncomfortable
Sponsored Article
Life in Jordan: 'Undiscovered treasure'
Rhineland
Story of a fugitive cow who outwitted police for weeks before capture
Culture
Eleven famous Germans with surnames that'll make your sides split
Lifestyle
The best ways to get a visa as an American in Germany
Sponsored Article
Why Jordan is the ‘Different’ East
Gallery
Germany's 17 Olympic gold medals in pictures
Sponsored Article
Five things Americans should know about voting abroad
14 facts you never knew about the Brandenburg Gate
Society
Ten times Germans proved they really, really love beer
Sponsored Article
Jordan Pass: your ticket to the experience of a lifetime
Lifestyle
What's on in Germany: events for August 2016
Sponsored Article
Jordan: where history meets adventure
National
Six things you need to know when moving to Germany
Travel
These 10 little-known German towns are a must see
Sponsored Article
6 reasons expats use TransferWise to send money
International
German scientists prove birds can sleep while flying
Sponsored Article
Why you should attend an international job fair
Technology
London v. Berlin: Which is better for startups?
Sponsored Article
Five things Americans should know about voting abroad
Lifestyle
13 mortifying mistakes German learners always make
Sponsored Article
Jordan: where history meets adventure
Travel
Enter if you dare: Berlin's best abandoned haunts
Sponsored Article
6 reasons expats use TransferWise to send money
Lifestyle
10 rookie errors all Brits make when they arrive in Germany
National
How to get German citizenship (or just stay forever)
Technology
Brexit will turn Berlin into 'Europe’s startup capital'
Travel
Six soothing day trips to escape the bustle of Berlin
International
'Germany needs to make UK come to its senses'
Features
Six odd things Germans do in the summer
7,595
jobs available
Toytown Germany
Germany's English-speaking crowd