Artist, Javad Soleimanpour
Wednesday, February 28, 2018
Monday, February 26, 2018
White Dwarf Stars and Other Wonders
White dwarf’s inner makeup is mapped for the first time
Tiny changes in a white dwarf’s brightness reveal that the stellar corpse has more oxygen in its core than expected, researchers report online January 8 in Nature. The finding could challenge theories of how stars live and die, and may have implications for measuring the expansion of the universe.
As a star ages, it sheds most of its gas into space until all that remains is a dense core of carbon and oxygen, the ashes of a lifetime of burning helium. That core, plus a thin shellacking of helium, is called a white dwarf.
Luckily, some white dwarfs encode their inner nature on their surface. These stars change their brightness in response to internal vibrations. Astrophysicists can infer a star’s internal structure from the vibrations, similar to how geologists learn about Earth’s interior by measuring seismic waves during an earthquake.
Saturn’s rings, made of countless icy particles, form a translucent veil in this view from NASA’s Cassini spacecraft.
Saturn's moon Titan sports Earth-like features
Using the now-complete Cassini data set, Cornell astronomers have created a new global topographic map of Saturn's moon Titan that has opened new windows into understanding its liquid flows and terrain.
The map revealed several new features on Titan, including new mountains, none higher than 700 meters. The map also provides a global view of the highs and lows of Titan's topography, which enabled the scientists to confirm that two locations in the equatorial region of Titan are in fact depressions that could be either ancient, dried seas or cryovolcanic flows.
The map also revealed that Titan is a little bit flatter -- more oblate -- than was previously known, which suggests there is more variability in the thickness of Titan's crust than previously thought.
Tiny changes in a white dwarf’s brightness reveal that the stellar corpse has more oxygen in its core than expected, researchers report online January 8 in Nature. The finding could challenge theories of how stars live and die, and may have implications for measuring the expansion of the universe.
As a star ages, it sheds most of its gas into space until all that remains is a dense core of carbon and oxygen, the ashes of a lifetime of burning helium. That core, plus a thin shellacking of helium, is called a white dwarf.
Luckily, some white dwarfs encode their inner nature on their surface. These stars change their brightness in response to internal vibrations. Astrophysicists can infer a star’s internal structure from the vibrations, similar to how geologists learn about Earth’s interior by measuring seismic waves during an earthquake.
Using the now-complete Cassini data set, Cornell astronomers have created a new global topographic map of Saturn's moon Titan that has opened new windows into understanding its liquid flows and terrain.
The map revealed several new features on Titan, including new mountains, none higher than 700 meters. The map also provides a global view of the highs and lows of Titan's topography, which enabled the scientists to confirm that two locations in the equatorial region of Titan are in fact depressions that could be either ancient, dried seas or cryovolcanic flows.
The map also revealed that Titan is a little bit flatter -- more oblate -- than was previously known, which suggests there is more variability in the thickness of Titan's crust than previously thought.
Friday, February 23, 2018
Book Review: Into the Fire by Elizabeth Moon
I pick up a new Elizabeth Moon novel
with anticipatory delight. In its pages (or phosphors, for the ebook version),
I will find fascinating characters with skills and intelligence, subtle
conflicts of culture, superbly handled tension and plot twists, and insights
into people who are different from me. Unlike the heroine of Into the Fire (and Moon herself), I have
no military experience whatsoever (30 years of Chinese martial arts
notwithstanding). I was a long-haired, sign-waving war protester. Most military
fiction leaves me looking around for those love beads. But not Moon’s, and a
big part of that (aside from her sheer story-telling skill) is the intelligence
and compassion of her military characters.
In the previous novel, Cold
Welcome, Ky Vatta and an assortment of people under her command and
not-under-her-command manage to survive a shuttle crash into icy waters and
make their way to an abandoned base in a frigid, barren landscape. Their
survival depends not only working together and making the best decisions but a
huge measure of luck. Ky’s training and experience give her a structure to
establish leadership and discern what must be done, and by whom, and in what
order, how to best use the skills of the others, how to resolve conflicts
without squelching initiative. Most of the book centers on how leadership,
delegation protocols, the balance between negotiation and creativity and
obedience, and the skills to construct and carry out strategic planning can
save lives. In fact, there’s very little shoot-‘em-up and a great deal of wow, these people have thought carefully
about how to manage desperate situations. Into the Fire continues that story.
After the grand finale and rescue, Ky might think her ordeal
is over. Ha! Her meticulously collected records of the sabotage go missing and
her people mysteriously disappear, drugged and kept incommunicado by forces
inimical to her family. The focus shifts from physical to political survival.
Sabotage, betrayal, immigration raids, poisoning, and a rescue executed in
typical Ky Vatta style build and sustain tension. Again I was impressed by the
skillfulness with which Ky and her companions make and execute plans, whether
it’s marshalling an academy full of unseasoned cadets to defend the planetary
president or nab the drugged prisoners from several different locations. Ky
didn’t just jump into action, as characters in many other military novels so
often do. She didn’t say, “Trust me, just do what I say” to her subordinates.
She conferred with those with expertise, made plans, revised them, revised them
again, made backup plans and backups to the backups, made sure everyone had the
information they needed to do the best, smartest job. Things went wrong, as of
course they must in fiction. And that’s half the fun of the adventure.
Moon provides enough backstory for Into the Fire to stand on its own, but I recommend reading it
together with Cold Welcome. And I do
recommend it!
Thursday, February 22, 2018
If You Were a Story...
“We are not quite novels.
We are not quite short stories.
In the end, we are collected works.”
― Gabrielle Zevin, The Storied Life of A.J. Fikry
Wednesday, February 21, 2018
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