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

Apr 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: Astronomers see pebbles poised to make planets

Related Stories

Uranus' moon Umbriel

Jun 08, 2015

The 19th century was an auspicious time for astronomers and planet hunters. In addition to the discovery of the Asteroid Belt that rests between Mars and Jupiter – as well as the many minor planets within ...

The solar system and beyond is awash in water

Apr 08, 2015

As NASA missions explore our solar system and search for new worlds, they are finding water in surprising places. Water is but one piece of our search for habitable planets and life beyond Earth, yet it links ...

Recommended for you

Astronomers see pebbles poised to make planets

20 hours ago

A team of astronomers led from St Andrews and Manchester universities today (6 July) announced the discovery of a ring of rocks circling a very young star. This is the first time these 'pebbles', thought ...

Small cosmic 'fish' points to big haul for SKA Pathfinder

21 hours ago

A wisp of cosmic radio waves, emitted before our solar system was born, shows that a new radio telescope will be able to detect galaxies other telescopes can't. The work, led by Dr James Allison of the Commonwealth ...

Gaia produces stellar density map of the Milky Way

21 hours ago

This image, based on housekeeping data from ESA's Gaia satellite, is no ordinary depiction of the heavens. While the image portrays the outline of our Galaxy, the Milky Way, and of its neighbouring Magellanic ...

Hubble view: Wolf-Rayet stars, intense and short-lived

Jul 03, 2015

This NASA/European Space Agency (ESA) Hubble Space Telescope picture shows a galaxy named SBS 1415+437 (also called SDSS CGB 12067.1), located about 45 million light-years from Earth. SBS 1415+437 is a Wolf-Rayet ...

NASA image: Stellar sparklers that last

Jul 03, 2015

While fireworks only last a short time here on Earth, a bundle of cosmic sparklers in a nearby cluster of stars will be going off for a very long time. NGC 1333 is a star cluster populated with many young ...

User comments : 0

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.