Sept. 23-24, 1846
Author: Kelli Mars
Publish Year: 2021
Neptune, the eighth planet circling the Sun, was found by astronomers on the nights of September 23 and 24, 1846. Utilizing mathematical computations of its expected position as a result of observable changes in the trajectory of the planet Uranus, the discovery was made. Neptune is too faint to be seen with the human eye due to its immense distance from the Sun, and thus the discovery was performed using a telescope. A moon surrounding Neptune was quickly found by astronomers, but it took over a century to find a second one. The scientific discoveries made during Voyager 2’s flyby of Neptune in 1989, including the establishment of dark rings around the planet and the finding of five more moons, dramatically expanded our understanding of distant Neptune.
| ASTRONOMER URBAIN LE VERRIER | ASTRONOMER URBAIN LE VERRIER | PHOTOGRAPH OF JOHANN GOTTFRIED GALLE |
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MIDDLE: A PORTRAIT OF ASTRONOMER URBAIN LE VERRIER, WHO DETERMINED NEPTUNE’S LOCATION INDEPENDENTLY.
RIGHT: A PHOTOGRAPH OF JOHANN GOTTFRIED GALLE TAKEN IN 1890. GALLE WAS THE FIRST TO RECOGNISE NEPTUNE AS THE EIGHTH PLANET.
The solar system currently has seven known planets after Uranus was discovered in 1781. Astronomers kept spotting abnormalities in the newly discovered planet’s orbit that Newton’s law of universal gravitation was unable to adequately account for. But these anomalies might be explained by the gravitational effects of a planet that is farther away. Astronomers Urbain Jean-Joseph Le Verrier in Paris and John Couch Adams in Cambridge, England, independently determined the location of this hypothetical planet by 1845, when Uranus had nearly completed one full circuit around the Sun.
Astronomer Johann Gottfried Galle made the first observations of the new planet on the night of September 23–24, 1846, using the Fraunhofer telescope at the Berlin Observatory, only 1 degree off Le Verrier’s estimated position. In retrospect, after Neptune’s official discovery, it was discovered that other astronomers, beginning with Galileo Galilei in 1612, had also noticed it but had failed to identify it as a planet due to its sluggish motion in relation to the background stars.
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Triton was found by astronomer William Lassell, who is pictured on the right.
Using a self-built telescope, astronomer William Lassell found a moon orbiting Neptune on October 10, 1846, barely 17 days after the planet’s discovery. A second moon, Nereid, was discovered in 1949, but it wasn’t until then that the moon was given the formal name Triton. In 1981, a third moon was found after a fruitless hunt for rings around the earth. Beyond some fundamental knowledge, much of Neptune remained a mystery due to its extreme distance from the Sun—roughly 30 times that of the Earth. Neptune was known to be the 4th biggest planet in the solar system and, like the other gas giants, had large hydrogen and helium-based atmosphere. Its cloud tops were thought to have been about 55 Kelvin, or minus 361 degrees Fahrenheit. On average, Neptune had a 16-hour day.
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Triton, the moon of Neptune, as seen in a Voyager 2 photograph. Middle: A photo taken by Voyager 2 of Neptune’s hazy rings. Below: Three days after making its closest approach to the planet, Voyager 2 captured this image of a backlit Neptune, top, and Triton.
Voyager 2 passed 3,408 miles above Neptune’s north pole on August 25, 1989, when it came the closest to any planet since it first left Earth in 1977. The spacecraft returned more than 9,000 images of the planet, its moons, and its rings during its four-month observation period, along with a wealth of scientific data. The Great Dark Spot, a huge storm, and clouds in the planet’s upper atmosphere were captured on camera by Voyager 2. The satellite saw clouds and haze in the atmosphere of the 840-mile-wide moon Triton and discovered geyser-like phenomena in its northern cap.
Voyager 2 confirmed that a pair of dark rings surrounds the planet and found five more inner moons. A 14th moon was found in 2013 in photographs from the Hubble Space Telescope obtained in 2009, while five additional minor moons were found in 2001 using a big ground-based telescope.
World historical events in 1846:
February 19 – Austin is where the Texas state government is formally constituted.
February 26 – Philadelphia’s Liberty Bell makes a cracking noise when rung on George Washington’s birthday.
June 15 – The 49th parallel is the border in between United States and Canada according to the Oregon Treaty.
June 28 – Antoine-Joseph “Adolfe” Saxe obtained a patent for the saxophone.
August 3 – Illinois’ Abraham Lincoln wins a seat in the U.S. House of Representatives.
August 10 – The Smithsonian Institution is founded by the US Congress.
September 10 – The first sewing machine patent in the United States is given to Elias Howe.
September 30 – William Morton, a dentist from the United States, uses ether anaesthetic for the first time.
Source: nasa.gov
Author Credits:
John Uri
NASA Johnson Space Center
Last Updated: Sep 24, 2021
Editor: Kelli Mars
NASA History, Voyager
Latest News: 22.09.2022. Source: nasa.gov
Webb Image Captures New The most crystal clear view of Neptune’s rings in decades
With its first image of Neptune, NASA’s James Webb Space Telescope displays its capabilities closer to home. In addition to providing the best glimpse of the planet’s rings in more than 30 years, Webb’s cameras also shed new insight on the ice giant.
The clarity of the planet’s rings, some of which have not been seen since NASA’s Voyager 2 became the first spacecraft to examine Neptune during its approach in 1989, is what stands out most in Webb’s latest photograph. The Webb image vividly displays Neptune’s fainter dust bands in addition to many brilliant, narrow rings.