Earth’s Inner Core Rotation Slower Than Estimated

Earth’s Inner Core Rotation Slower Than Estimated

“Scientists at the University of Cambridge believe they have achieved the first accurate estimate of how much faster Earth’s core is rotating compared to the rest of the planet. The rate—about one degree every million years—is much slower than previously thought and arises from the complex dynamic between Earth’s inner and outer core, which generates Earth’s geomagnetic field. Without our magnetic field, Earth’s surface would not be protected from charged particles spewing from the Sun, and life would not be able to exist.”

Un degre par million d’annees!

The Moon Has a Fluid Outer Core

slashdot.org: The Moon Has a Fluid Outer Core

The new research confirms the existence of a solid inner core and liquid outer layer, similar to Earth’s. Unlike Earth, the moon also has a partly melted, mushy layer over that.

Seismic Detection of the Lunar Core

Abstract:
Despite recent insight regarding the history and current state of the Moon from satellite sensing and analyses of limited Apollo-era seismic data, deficiencies remain in our understanding of the deep lunar interior. We reanalyzed Apollo lunar seismograms using array processing methods to search for the presence of reflected and converted seismic energy from the core. Our results suggest the presence of a solid inner and fluid outer core, overlain by a partially molten boundary layer. The relative sizes of the inner and outer core suggest that the core is ~60% liquid by volume. Based on phase diagrams of iron alloys and the presence of partial melt, the core likely contains less than 6 weight % of lighter alloying components, which is consistent with a volatile-depleted interior.

Farewell, Pioneer Anomaly?

Cosmic Variance : Farewell, Pioneer Anomaly?

Five years have passed. Using the telemetry data, the two scientists created an extremely elaborate “finite element” 3-D computer model of each Pioneer spacecraft, in which the thermal properties of 100,000 positions on their surfaces are independently tracked for the duration of the 30-year mission.

But according to Toth, “You can take it to the bank that whatever remains of the anomaly after accounting for that thermal acceleration, it will at most be much less than the canonical value of 8.74 x 10-10 m/s2, and then, mind you, all those wonderful numerical coincidences people talk about are destroyed.”