Did William Herschel Discover The Rings Of Uranus In The 18th Century?

April 16, 2007

In a paper presented at the National Astronomy Meeting in Preston from 16 – 20 April, Dr Stuart Eves of Surrey Satellite Technology Limited will challenge the orthodox view that the rings around the planet Uranus were first detected during an occultation experiment in 1977.

Remarkably, a paper presented to the Royal Society in December 1797 by the then King's Astronomer, Sir William Herschel, (who had discovered Uranus in 1781), includes a description of a possible ring around the planet. Dr Eves believes this is the first observation of the rings that were not seen again for almost two hundred years.

Even Herschel was unable to confirm his possible sightings, and they were not repeated by several generations of astronomers who came after him. (Prior to 1977, when astronomers thought that Uranus lacked rings, Herschel’s claims were dismissed as “clearly erroneous”. And even after 1977, when the existence of the rings was finally established, it was suggested that the rings were far too dim to have been detected by Herschel’s telescopes, and so his claim to priority was ignored).

However, a recent re-evaluation of Herschel’s 1797 paper by Dr Stuart Eves of Surrey Satellite Technology Limited, suggests that Herschel’s claim to have seen one of the rings may well have been correct.

“Herschel got a lot of things right”, notes Dr Eves, “He has a ring of roughly the correct size relative to the planet, and he also has the orientation of this ring in the right direction. In addition, he accurately describes the way the appearance of the ring changes as Uranus moves around the Sun, and he even gets its colour right. Uranus’s Epsilon ring is somewhat red in colour, a fact only recently confirmed by the Keck telescope, and Herschel mentions this in his paper.”

But if Herschel could see the Epsilon ring in the late 1700’s, why did no-one else follow up his observations in subsequent years as the telescopes astronomers used improved? “There are several mechanisms that could account for this”, suggests Dr Eves, “The current Cassini satellite mission to Saturn is telling us that its rings are becoming darker and also expanding, (becoming more diffuse), over time.

If these same mechanisms are also operating at Uranus, then the appearance of its rings could have changed quite markedly over 200 years, making them much harder to detect.” Herschel’s observations could thus be proof that planetary ring systems in our solar system are far more dynamic than has previously been supposed.

Source: Royal Astronomical Society

Explore further: In 40 million years, Mars may have a ring (and one fewer moon)

Related Stories

Finding new worlds with a play of light and shadow

October 31, 2015

Astronomers have used many different methods to discover planets beyond the solar system, but the most successful by far is transit photometry, which measures changes in a star's brightness caused by a mini-eclipse. When ...

Saturn's "Yin-Yang" moon Iapetus

October 29, 2015

Thanks to the Cassini mission, a great many things have been learned about the Saturn system in recent years. In addition to information on Saturn's atmosphere, rotation and its beautiful and extensive ring system, many revelations ...

The Lords of the Rings among centaurs

September 14, 2015

(Phys.org)—Chariklo, the largest known centaur object, orbiting in a region between Saturn and Uranus, is a very intriguing celestial body that surprised astronomers last year. This remote minor planet has unveiled the ...

The gas (and ice) giant Neptune

September 14, 2015

Neptune is the eight planet from our Sun, one of the four gas giants, and one of the four outer planets in our Solar System. Since the "demotion" of Pluto by the IAU to the status of a dwarf planet – and/or Plutoid and ...

The moons of Neptune

September 9, 2015

Neptune, that icy gas giant that is the eight planet from our Sun, was discovered in 1846 by two astronomers – Urbain Le Verrier and Johann Galle. In keeping with the convention of planetary nomenclature, Neptune was named ...

Recommended for you

Aging star's weight loss secret revealed

November 25, 2015

A team of astronomers using ESO's Very Large Telescope has captured the most detailed images ever of the hypergiant star VY Canis Majoris. These observations show how the unexpectedly large size of the particles of dust surrounding ...

Scientists detect stellar streams around Magellanic Clouds

November 23, 2015

(Phys.org)—Astronomers from the University of Cambridge, U.K., have detected a number of narrow streams and diffuse debris clouds around two nearby irregular dwarf galaxies called the Magellanic Clouds. The research also ...

NASA images: A day on Pluto, a day on Charon

November 20, 2015

Pluto's day is 6.4 Earth days long. The images were taken by the Long Range Reconnaissance Imager (LORRI) and the Ralph/Multispectral Visible Imaging Camera as the distance between New Horizons and Pluto decreased from 5 ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.