Stuart Eves Credits William Herschel With Uranian Epsilon Ring in 1789

Summary: Surrey Satellite Technology Limited’s Stuart Eves suggests William Herschel saw Uranian epsilon ring in 1789, in a new look at Herschel’s notes.

Uranus and the planet's outermost ring, the epsilon ring; computerized summation of six images obtained Nov. 28, 1985, by spacecraft Voyager 2’s ISS (Imaging Science Subsystem) narrow-angle camera (NAC) from a range of 72.3 million kilometers (44.9 million miles); NASA ID ARC-1985-A86-7001; image credit NASA / JPL-Caltech: Generally not subject to copyright in the United States, via NASA Image and Video Library

Surrey Satellite Technology Limited’s Stuart Eves suggests William Herschel saw the Uranian epsilon ring in 1789, according to the astrophysicist and space safety expert’s new look at the German-British astronomer’s observations.

Dr. Stuart Eves officially presented his new look at Uranian ring observations made by William Herschel (Nov. 15, 1738-Aug. 25, 1822) at the 2007 National Astronomy Meeting. The Royal Astronomical Society (RAS) held the prestigious annual conference from Monday, April 16, to Friday, April 20, 2007, at the University of Central Lancashire’s (UCLan) Centre for Astrophysics in Preston, North West England.

William Herschel (Nov. 15, 1738-Aug. 25, 1822) shared findings from his 10-year search for a Uranian ring system at the Royal Society of London’s Dec. 14, 1797, meeting. He reported ringed and ringless observations.

Herschel extensively described ringed views that he obtained on March 16, 1789. “The ring is short, not like that of Saturn . . . . It is remarkable that the two annae seem of a colour a little inclined to red . . . .” (page 68).

In his “Remarks Upon the Foregoing Observations,” however, Herschel cited a ringless view as critical to his assessment of a ringless system. “Placing therefore great confidence on the observation of March 5, 1792, supported by my late views of the planet, I venture to affirm, that it has no ring in the least resembling that, or rather those, of Saturn” (page 70).

Yet, in a post-1792 observation, he had noted: “Dec. 4, 1793. 7-feet reflector, power 287. The Georgian planet is not so well defined as, from the extraordinary distinctness of my present 7-feet telescope, it ought to be. There is a suspicion of some apparatus about the planet” (page 69).

In a re-evaluation of Herschel’s annular observations, Dr. Eves finds a consistent rightness of details with the Uranian system’s now-known epsilon (ε) ring.

In an April 16, 2007, press release, Royal Astronomical Society press officers Robert Massey and Anita Heward reveal: “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 color, a fact only recently confirmed by the Keck telescope, and Herschel mentions this in his paper.”

Dr. Eves offers several explanations for the lack of observations of the Uranian ring system in the 190 years between Herschel’s discernments, which date back, at least, to March 4, 1787, and the serendipitous detection of at least five rings on March 10,1977, via the Kuiper Airborne Observatory. The planet’s extremely tilted axial geometry greatly limits the opportunities for Earth-based observations of the Uranian ring system.

Also, Dr. Eves references the Cassini-Huygens spacecraft’s observations of the darkening of the Saturnian ring system as a process that might also affect the Uranian ring system. The unknown brightening-darkening phenomena could have operated to brighten the Uranian ring system in the late 18th century.

“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,” notes the Royal Astronomical Society’s press release.

Earth’s atmosphere could also interfere with the ring system’s observability, according to BBC News science reporter Paul Rincon’s April 18, 2007, article on Dr. Eves’ presentation. The light pollution and smog created by the Industrial Revolution, which approximately began in the last half of the 18th century, have disturbed the clarity of the night sky environment.

The takeaway for Surrey Satellite Technology Limited’s Stuart Eve’s suggestion that William Herschel could have seen the Uranian epsilon ring is that the astrophysicist and space security expert’s new look at Herschel’s 1797 report of ringed and ringless views of Uranus finds details in the German-British astronomer’s descriptions that accord with the Uranian ring system.

high-resolution image of Uranian system’s bright outer ring, the epsilon ring, obtained Jan. 23, 1986, from a distance of 1.12 million kilometers (690,000 miles) by Voyager 2’s ISS (Imaging Science Subsystem) narrow-angle camera (NAC); the approximate width of 100 kilometers (60 miles) at this section of the epsilon ring shows structural variations of a broad, bright outer component, approximately 40 kilometers (25 miles) wide; a comparably wide, darker middle region; and a narrow, brighter inner strip, approximately 15 kilometers (9 miles) in width; NASA ID PIA01983; ARC-1986-A86-7022; P-2950BW; NASA ID PIA01983; image addition date 1999-06-30; image credit NASA / JPL: May be used for any purpose without prior permission, via NASA JPL Photojournal

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Uranus and the planet's outermost ring, the epsilon ring; computerized summation of six images obtained Nov. 28, 1985, by spacecraft Voyager 2’s ISS (Imaging Science Subsystem) narrow-angle camera (NAC) from a range of 72.3 million kilometers (44.9 million miles); NASA ID ARC-1985-A86-7001; image credit NASA / JPL-Caltech: Generally not subject to copyright in the United States; may use this material for educational or informational purposes, including photo collections, textbooks, public exhibits, computer graphical simulations and Internet Web pages; general permission extends to personal Web pages, via NASA Image and Video Library @ https://images.nasa.gov/details-ARC-1985-A86-7001

high-resolution image of Uranian system’s bright outer ring, the epsilon ring, obtained Jan. 23, 1986, from a distance of 1.12 million kilometers (690,000 miles) by Voyager 2’s ISS (Imaging Science Subsystem) narrow-angle camera (NAC); the approximate width of 100 kilometers (60 miles) at this section of the epsilon ring shows structural variations of a broad, bright outer component, approximately 40 kilometers (25 miles) wide; a comparably wide, darker middle region; and a narrow, brighter inner strip, approximately 15 kilometers (9 miles) in width; NASA ID PIA01983; ARC-1986-A86-7022; P-2950BW; NASA ID PIA01983; image addition date 1999-06-30; image credit NASA / JPL: May be used for any purpose without prior permission, via NASA JPL Photojournal @ https://photojournal.jpl.nasa.gov/catalog/PIA01983;
Generally not subject to copyright in the United States; may use this material for educational or informational purposes, including photo collections, textbooks, public exhibits, computer graphical simulations and Internet Web pages; general permission extends to personal Web pages, via NASA Image and Video Library @ https://images.nasa.gov/details-PIA01983

For further information:

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Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/49109920
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SM Dana Centre ‏@DanaCentre. “Have been reading about William Herschel in 'The Age of Wonder'. Looking forward to Stuart Eves' talk on him tonight http://budurl.com/lsf5.” Twitter. Oct. 19, 2010.
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