Photo, above: An image from a NASA animation showing 'tides' on Titan raised by Saturn's gravity, as detected by NASA's Cassini spacecraft. The fact that Titan gets squeezed and stretched depending on its orbit around Saturn suggests the presence of an ocean beneath its surface, a recent study has found. (NASA)

If confirmed, it would catapult Titan into an elite class of solar system moons harboring water, an essential ingredient for life. Titan boasts methane-filled seas at the poles and a possible lake near the equator. And it's long been speculated that Titan contains a hidden liquid layer, based on mathematical modeling and electric field measurements made by the Huygens spacecraft that landed on the surface in 2005. The latest evidence is still indirect, but outside scientists said it's probably the best that can be obtained short of sending a spacecraft to drill into the surface — a costly endeavor that won't happen anytime soon.

JOHN BATCHELOR SHOW

Hour One

Saturday 4 August  2013 / Hour 1, Block A: Ken Croswell, Science magazine, in re: ScienceShot: Reconstructing Galactic History  How did our galaxy form and evolve? To find out, astronomers try to ascertain the ages of the Milky Way's oldest components. Especially useful are globular clusters, old, tight-packed stellar gatherings that serve as time capsules preserving conditions from the Milky Way's youth. Now, as astronomers report online today in Nature, Hubble observations of white dwarf stars have nailed down the age of the great globular cluster 47 Tucanae (shown). Located 15,000 light-years from Earth, this cluster is the second brightest globular in the sky, after Omega Centauri. The new data reveal that 47 Tucanae is 9.9 billion years old, plus or minus 700 million years. For a globular, the cluster is metal-rich—its iron-to-hydrogen ratio is a fifth of the sun's—and is 2 billion years younger than a metal-poor globular dated with the same technique. Metal-poor and metal-rich globulars belong to two different components of the Milky Way, so these ages help reconstruct galactic history. Metal-poor globulars are part of the ancient stellar halo surrounding the Milky Way's disk, while metal-rich globulars reside in the galaxy's bulge and thick disk; therefore, the difference in age means that billions of years elapsed from the formation of the stellar halo to the birth of the thick disk.

Saturday 4 August  2013 / Hour 1, Block B:  Ken Croswell, Science magazine, in re: ScienceShot: New Moon Over Neptune It's not just Pluto that's getting new moons. The same spacecraft—in fact, the same scientist—that discovered two new moons orbiting Pluto has now spotted a new satellite around Neptune, boosting its total retinue of known moons to 14 and further proving the power of the Hubble Space Telescope. Astronomers glimpsed Neptune's first and largest satellite, Triton, shortly after the planet's 1846 discovery, but more than a century elapsed before they sighted its second. In 1989, the Voyager 2 spacecraft flew past Neptune and quadrupled the number known, so during the 1990s the eighth planet from the sun had eight known satellites. Searches during the 21st century raised the figure further. Despite the new discovery (circled in yellow), Neptune's moon count lags the other giant planets, but that may simply be because it's farther and its moons are harder to see. The new satellite is the smallest ever seen around Neptune, but surely the greatest question confronting scientists: Will William Shatner succeed in getting this one named Vulcan?

Tides control the geysers of Enceladus  The water geysers of Enceladus spew the most material when the small moon ventures farthest from Saturn, planetary scientists in the US have found. This discovery confirms a prediction of a theory that says the geysers' strength depends on Saturn's tide.  Discovered by the German-born English astronomer William Herschel in 1789, eight years after he spotted the planet Uranus, Enceladus is the sixth largest of Saturn's 62 known satellites. The small moon is 238,000 km from Saturn's centre, about two-thirds of the distance from the Earth to the Moon. Because Saturn is so massive, though, its gravity forces Enceladus to circle it every 1.37 days.  With a diameter of just 500 km, Enceladus is only one-seventh the size of the Earth's Moon so has far fewer radioactive elements, which heat the Earth's interior. This makes it an unlikely world for geysers or any other geological activity.

    Icy spray  In 1980 and 1981 NASA's Voyager 1 and 2 spacecraft flew past the ringed planet and found Enceladus's surface unusually smooth. This suggested that something was erasing its craters. Then in 2005 the Cassini spacecraft discovered water vapour around Enceladus. Cassini soon found the surprising source: geysers around the moon's south pole shoot water vapour and ice particles hundreds of kilometres above the surface. Some of this material settles on the surface of the moon, covering its craters.  Now planetary scientist Matthew Hedman of Cornell University and his colleagues have examined 252 near-infrared images from Cassini. "The brightness of the plume varied quite a bit," says Hedman, who found it four times brighter when Enceladus is farthest from Saturn than when closest. These observations agree with a prediction made in a paper published in 2007 by Terry Hurford of the Goddard Space Science Center in Maryland, who had calculated how Enceladus would respond to Saturn's tide.  Tides arise when gravity pulls on an extended object. For example, lunar gravity tugs strongest on the side of the Earth facing the Moon, lifting the sea. Likewise, on the opposite side of the Earth, the Moon's gravity pulls our planet's centre out from under the sea, producing a high tide on the far side as well. Elsewhere, tides from Jupiter power the fiery moon Io, which sports active volcanoes, and melt ice beneath the surface of the moon Europa.

     Tiger stripes   Saturnian tides are . . .  [more]

Saturday 4 August  2013 / Hour 1, Block C:  The Lucky Ones: One Family and the Extraordinary Invention of Chinese America by Mae Ngai (1 of 2) 

Saturday 4 August  2013 / Hour 1, Block D: The Lucky Ones: One Family and the Extraordinary Invention of Chinese America by Mae Ngai  (2 of 2)

Hour Two

Saturday 4 August  2013 / Hour 2, Block A:  Deep Future: The Next 100,000 Years of Life on Earth by Curt Stager (1 of 2)

Saturday 4 August  2013 / Hour 2, Block B: Deep Future: The Next 100,000 Years of Life on Earth by Curt Stager (2 of 2)

Saturday 4 August  2013 / Hour 2, Block C: Sid Perkins, Sciece magazine, in re: ScienceShot: Honey, I Shrank the Horse | Science/AAAS | News  . . . these "protohorses" became even smaller, shrinking to the size of a house cat . . .

Saturday 4 August  2013 / Hour 2, Block D: Carl Zimmer, NYT, in re: canine pals.

Dogs - From Fearsome Predator to Man's Best Friend - NYTimes.com  Dogs may have evolved from wolves, but the  . . .

Hour Three

Saturday 4 August  2013 / Hour 3, Block A: The Black Count: Glory, Revolution, Betrayal, and the Real Count of Monte Cristo by Tom Reiss  (1 of 4)

Saturday 4 August  2013 / Hour 3, Block B: The Black Count: Glory, Revolution, Betrayal, and the Real Count of Monte Cristo by Tom Reiss  (2 of 4)

Saturday 4 August  2013 / Hour 3, Block C: The Black Count: Glory, Revolution, Betrayal, and the Real Count of Monte Cristo by Tom Reiss  (3 of 4) 

Saturday 4 August  2013 / Hour 3, Block D: The Black Count: Glory, Revolution, Betrayal, and the Real Count of Monte Cristo by Tom Reiss  (4 of 4)

Hour Four

Saturday 4 August  2013 / Hour 4, Block A: The Race for What's Left: The Global Scramble for the World's Last Resources by Michael T. Klare (1 of 2) 

Saturday 4 August  2013 / Hour 4, Block B: The Race for What's Left: The Global Scramble for the World's Last Resources by Michael T. Klare (2 of 2)

Saturday 4 August  2013 / Hour 4, Block C: Ken Croswell, Science magazine, in re: ScienceShot: Reconstructing Galactic History  How did our galaxy form and evolve? To find out, astronomers try to ascertain the ages of the Milky Way's oldest components. Especially useful are globular clusters, old, tight-packed stellar gatherings that serve as time capsules preserving conditions from the Milky Way's youth. Now, as astronomers report online today in Nature, Hubble observations of white dwarf stars have nailed down the age of the great globular cluster 47 Tucanae (shown). Located 15,000 light-years from Earth, this cluster is the second brightest globular in the sky, after Omega Centauri. The new data reveal that 47 Tucanae is 9.9 billion years old, plus or minus 700 million years. For a globular, the cluster is metal-rich—its iron-to-hydrogen ratio is a fifth of the sun's—and is 2 billion years younger than a metal-poor globular dated with the same technique. Metal-poor and metal-rich globulars belong to two different components of the Milky Way, so these ages help reconstruct galactic history. Metal-poor globulars are part of the ancient stellar halo surrounding the Milky Way's disk, while metal-rich globulars reside in the galaxy's bulge and thick disk; therefore, the difference in age means that billions of years elapsed from the formation of the stellar halo to the birth of the thick disk.

Saturday 4 August  2013 / Hour 4, Block D: Ken Croswell, Science magazine, in re: ScienceShot: New Moon Over Neptune It's not just Pluto that's getting new moons. The same spacecraft—in fact, the same scientist—that discovered two new moons orbiting Pluto has now spotted a new satellite around Neptune, boosting its total retinue of known moons to 14 and further proving the power of the Hubble Space Telescope. Astronomers glimpsed Neptune's first and largest satellite, Triton, shortly after the planet's 1846 discovery, but more than a century elapsed before they sighted its second. In 1989, the Voyager 2 spacecraft flew past Neptune and quadrupled the number known, so during the 1990s the eighth planet from the sun had eight known satellites. Searches during the 21st century raised the figure further. Despite the new discovery (circled in yellow), Neptune's moon count lags the other giant planets, but that may simply be because it's farther and its moons are harder to see. The new satellite is the smallest ever seen around Neptune, but surely the greatest question confronting scientists: Will William Shatner succeed in getting this one named Vulcan?

Tides control the geysers of Enceladus  The water geysers of Enceladus spew the most material when the small moon ventures farthest from Saturn, planetary scientists in the US have found. This discovery confirms a prediction of a theory that says the geysers' strength depends on Saturn's tide.  Discovered by the German-born English astronomer William Herschel in 1789, eight years after he spotted the planet Uranus, Enceladus is the sixth largest of Saturn's 62 known satellites. The small moon is 238,000 km from Saturn's centre, about two-thirds of the distance from the Earth to the Moon. Because Saturn is so massive, though, its gravity forces Enceladus to circle it every 1.37 days.  With a diameter of just 500 km, Enceladus is only one-seventh the size of the Earth's Moon so has far fewer radioactive elements, which heat the Earth's interior. This makes it an unlikely world for geysers or any other geological activity.

    Icy spray  In 1980 and 1981 NASA's Voyager 1 and 2 spacecraft flew past the ringed planet and found Enceladus's surface unusually smooth. This suggested that something was erasing its craters. Then in 2005 the Cassini spacecraft discovered water vapour around Enceladus. Cassini soon found the surprising source: geysers around the moon's south pole shoot water vapour and ice particles hundreds of kilometres above the surface. Some of this material settles on the surface of the moon, covering its craters.  Now planetary scientist Matthew Hedman of Cornell University and his colleagues have examined 252 near-infrared images from Cassini. "The brightness of the plume varied quite a bit," says Hedman, who found it four times brighter when Enceladus is farthest from Saturn than when closest. These observations agree with a prediction made in a paper published in 2007 by Terry Hurford of the Goddard Space Science Center in Maryland, who had calculated how Enceladus would respond to Saturn's tide.  Tides arise when gravity pulls on an extended object. For example, lunar gravity tugs strongest on the side of the Earth facing the Moon, lifting the sea. Likewise, on the opposite side of the Earth, the Moon's gravity pulls our planet's centre out from under the sea, producing a high tide on the far side as well. Elsewhere, tides from Jupiter power the fiery moon Io, which sports active volcanoes, and melt ice beneath the surface of the moon Europa.

     Tiger stripes   Saturnian tides are . . .  [more]

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Music

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