On This Day: Neptune found using math!, but is there a Planet Nine?? - Sep. 23, 1846
(edited from Wikipedia)
"
The planet Neptune was mathematically predicted before it was directly observed. With a prediction by Urbain Le Verrier, telescopic observations confirming the existence of a major planet were made on the night of September 23–24, 1846, at the Berlin Observatory, by astronomer Johann Gottfried Galle (assisted by Heinrich Louis d'Arrest), working from Le Verrier's calculations. It was a sensational moment of 19th-century science, and dramatic confirmation of Newtonian gravitational theory. In François Arago's apt phrase, Le Verrier had discovered a planet "with the point of his pen".
In retrospect, after it was discovered, it turned out it had been observed many times before but not recognized, and there were others who made various calculations about its location which did not lead to its observation. By 1846, the planet Uranus had completed nearly one full orbit since its discovery by William Herschel in 1781, and astronomers had detected a series of irregularities in its path that could not be entirely explained by Newton's law of universal gravitation. These irregularities could, however, be resolved if the gravity of a farther, unknown planet were disturbing its path around the Sun. In 1845, astronomers Urbain Le Verrier in Paris and John Couch Adams in Cambridge separately began calculations to determine the nature and position of such a planet. Le Verrier's success also led to a tense international dispute over priority.
The conventional wisdom that Neptune's discovery should be "credited to both Adams and Le Verrier" has recently been challenged putting in doubt the accounts of Airy, Challis and Adams in 1846. A later Scientific American article by Sheehan, Kollerstrom and Waff claimed more boldly "The Brits Stole Neptune" and concluded "The achievement was Le Verrier's alone."
The discovery of Neptune led to the discovery of its moon, Triton, by William Lassell just seventeen days later.
Even before Neptune's discovery, some speculated that one planet alone was not enough to explain the discrepancy in Uranus' orbit. [It was postulated] that another planet, of roughly 12 Earth masses, must exist beyond Neptune.
As of 2022, no large planet has been found beyond Neptune that would explain any alleged discrepancy, despite the discovery of trans-Neptunian objects (most notably, Pluto). While the astronomical community widely agrees that "Planet X", as originally envisioned, does not exist, the concept of an as-yet-unobserved planet has been revived by a number of astronomers to explain other anomalies observed in the outer Solar System.
"
https://en.wikipedia.org/wiki/Discovery_of_Neptune
(edited from article)
"
Searching for Planet Nine
03.11.22 Science Update
The Solar System has eight planets. In 2006, astronomers reclassified Pluto as a dwarf planet, the same class as contains Eris, Sedna, Quaoar, Ceres and perhaps many more solar system small bodies. These are defined approximately as bodies that orbit the Sun but that are not massive enough (unlike regular planets) to gravitationally dominate their environments by clearing away material. Astronomers wonder, though, whether there might not really be a ninth planet previously undiscovered but lurking in the outer reaches of the solar system, perhaps in the giant Oort cloud of objects that begins hundreds of astronomical units (au) from the Sun and extends outward.
The notion that there may be a ninth massive planet in the outer solar system has taken on new appeal with recent data that show that the orbital parameters of some small bodies beyond Neptune (their inclinations, perihelions, and retrograde motions) seem to behave as though they had been influenced by the gravity of a massive object in the outer solar system.
Although these data suffer from observational biases and statistical uncertainties, they have triggered renewed interest in the idea of the presence of another planet. This speculative "Planet 9," according to estimates, would be about 5-10 Earth-masses in size and orbit about 400-800 au from the Sun. A planet at this distance would be extremely difficult to spot in normal optical sky searches because of its faintness, even to telescopes like PanSTARRS and LSST.
The study has been advanced by a team of researchers led by Sigurd Naess of the Institute of Theoretical Astrophysics at the University of Oslo, as a part of the Atacama Cosmology Telescope (ACT) collaboration led by Principal Investigator, Professor Suzanne Staggs of Princeton University. Their search found many tentative candidate sources (about 3500 of them) but none could be confirmed, and there were no statistically significant detections. The results cover only about 10-20% of the possibilities, but other sensitive millimeter facilities are coming online and should be able to complete this search for Planet 9 as hypothesized.
"
https://www.cfa.harvard.edu/news/searching-planet-nine
---------------------------------------------------------
On This Day: S.J. Moore joins this long list of presidential assassination plots - Sep. 22, 1975
https://www.democraticunderground.com/1016364070
On This Day: Defense of Marriage Act signed into law, later Biden signs its repeal - Sep. 21, 1996
https://www.democraticunderground.com/1016363991
On This Day: Lenape tribe land in PA swindled; no relief from 21st century courts - Sep. 20, 1737
https://www.democraticunderground.com/1016363877
On This Day: Jamestown burned, followed later by harsher slavery and race laws - September 19, 1676
https://www.democraticunderground.com/1016363789
On This Day: Sep. 18 death prophecy comes true. Seer's life spared. - in the year 96
https://www.democraticunderground.com/1016363670
= new reply since forum marked as read
