Tag: Magnetism

The Magnetic Depths

The emerging sub-genre of public service announcements about geological surveys—apparently offered not just due to FAA regulations, but to quell the growth of potential conspiracy theories—continues with this heads-up about a “low-flying airplane” over parts of Virginia and North Carolina.

[Image: USGS map of eastern Virginia, altered by BLDGBLOG.]

Of course, beyond the idea of simply preempting the development of new conspiracy theories, the work being done by the project is fascinating in and of itself: “Instruments on the airplane will measure variations in the Earth’s magnetic field and natural low-level radiation created by different rock types near and up to several miles beneath the surface. This information will help researchers develop geologic maps of the area that will be used to better understand sand resources and underground faults in the region.”

While we’re on the topic of the Virginia/North Carolina border region, I’m reminded of why there’s a strange “notch” in the state line, a story “that mostly involves collecting taxes and avoiding swamps”: “The rough and rowdy inhabitants living close to the border told North Carolina tax collectors they lived in Virginia, [Gates County historian Linda Hofler] said. When the Virginia tax man came, they said North Carolina was their home.”

In any case, check out the USGS for more on the low-flying geomagnetic airplane and The Virginian-Pilot for more on VA/NC border history.

(Related: Geomedia, or What Lies Below.)

Tone Fields Larger Than Stars

[Image: From “Probing Cosmic-Ray Transport with Radio Synchrotron Harps in the Galactic Center,” by Timon Thomas, Christoph Pfrommer, and Torsten Enßlin.]

The above image, as described by Susanna Kohler over at AAS Nova, depicts an ultra-large-scale magnetic “harp” near the center of our galaxy, emitting radio waves. The black lines apparently “span several light-years.”

As Kohler writes, where the parenthetical comments are her own, “a team of scientists argues that this cosmic music is caused by a massive star or a pulsar (a magnetized neutron star) plunging through an ordered magnetic field in the galactic center. As the star crosses (moving upward, in the image above) bundles of field lines, it discharges high-energy cosmic rays that travel in either direction along the bundles, emitting radio waves.”

It’s a kind of cosmic theremin—an instrument where the “musician controls volume and pitch using her hands to interfere with electromagnetic fields generated by the device”—a huge and ancient instrument playing itself in space.