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.
Significantly more productivity in USP lasers
06.12.2016 | Fraunhofer-Institut für Lasertechnik ILT
Shape matters when light meets atom
05.12.2016 | Centre for Quantum Technologies at the National University of Singapore
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
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07.12.2016 | Health and Medicine
07.12.2016 | Life Sciences
07.12.2016 | Health and Medicine