The make-up and temperature of Uranus’s rings


Pioneer cover

From the press release: From the moment he is handed a possibility of making the first alien contact, Saunders Maxwell decides he will do it, even if doing so takes him through hell and back.

 
Unfortunately, that is exactly where that journey takes him.

 
The vision that Zimmerman paints of vibrant human colonies on the Moon, Mars, the asteroids, and beyond, indomitably fighting the harsh lifeless environment of space to build new societies, captures perfectly the emerging space race we see today.


He also captures in Pioneer the heart of the human spirit, willing to push forward no matter the odds, no matter the cost. It is that spirit that will make the exploration of the heavens possible, forever, into the never-ending future.

 
Available everywhere for $3.99 (before discount) at amazon, Barnes & Noble, all ebook vendors, or direct from the ebook publisher, ebookit.
 

The rings of Uranus

New radio images taken by the ground-based telescopes by the ALMA and VLT telescopes in Chile have allowed scientists to better determine the make-up and temperature of the rings of Uranus.

The image above is from their paper. From the caption:

Images of the Uranian ring system at 3.1 mm (ALMA Band 3; 97.5 GHz), 2.1 mm (ALMA Band 4; 144 GHz), 1.3 mm (ALMA Band 6; 233 GHz), and 18.7 μm (VLT VISIR; 100 THz)…The planet itself is masked since it is very bright compared to the rings.

From the article above:

The new images taken by the Atacama Large Millimeter/submillimeter Array (ALMA) and the Very Large Telescope (VLT) allowed the team for the first time to measure the temperature of the rings: a cool 77 Kelvin, or 77 degrees above absolute zero — the boiling temperature of liquid nitrogen and equivalent to 320 degrees below zero Fahrenheit.

The observations also confirm that Uranus’s brightest and densest ring, called the epsilon ring, differs from the other known ring systems within our solar system, in particular the spectacularly beautiful rings of Saturn.

“Saturn’s mainly icy rings are broad, bright and have a range of particle sizes, from micron-sized dust in the innermost D ring, to tens of meters in size in the main rings,” said Imke de Pater, a UC Berkeley professor of astronomy. “The small end is missing in the main rings of Uranus; the brightest ring, epsilon, is composed of golf ball-sized and larger rocks.” [emphasis mine]

The mystery is why this ring has no dust, something not seen with any other ring system in the solar system, including the inner rings of Uranus itself..

Readers!
 

Every July, to celebrate the anniversary of the start of Behind the Black in 2010, I hold a month-long fund-raising campaign to make it possible for me to continue my work here for another year.
 

This year's fund-raising drive however is more significant in that it is also the 10th anniversary of this website's founding. It is hard to believe, but I have been doing this for a full decade, during which I have written more than 22,000 posts, of which more than 1,000 were essays and almost 2,600 were evening pauses.
 

This year's fund drive is also more important because of the growing intolerance of free speech and dissent in American culture. Increasingly people who don't like what they read are blatantly acting to blackball sites like mine. I have tried to insulate myself from this tyrannical effort by not depending on Google advertising or cross-posts Facebook or Twitter. Though this prevents them from having a hold on me, it also acts to limit my exposure.
 

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