First, the Owens Valley Observatory uses radio waves to illuminate the solar eclipse’s „ring of fire.”

The Owens Valley Radio Observatory used their improved long-wavelength array to capture a unique „radio eclipse” image during the Oct. 14 solar event, revealing detailed insights into the Sun’s corona and related phenomena.

A New Look at Solar Eclipses

As most Californians were treated to a partial solar eclipse on Oct. 14 (see lower right „visible” image showing the crescent moon peeking out from behind the moon), researchers at the Owens Valley Radio Observatory (OVRO) took a different view. Using OVRO’s Long Wavelength Array (OVRO-LWA), they measured radio wavelengths between 20 and 88 megahertz (MHz) to create an image of the „radio eclipse.”

In the images and video below, the dotted lines show the location of the Moon and the solid lines the limbs of the Sun. The distortions in the video are caused by the Sun’s ionosphere. Radio waves that extend beyond the edge of the Sun are emitted from its corona, creating a „ring of fire” effect that can be seen even outside the path of a total annular eclipse.

Nearing the maximum eclipse of the October 14 solar eclipse, recorded by the Owens Valley Radio Observatory – Long Wave Array (OVRO-LWA). The visible solar disk and occult lunar limb are outlined by solid and dotted circles, respectively. The radio sun is occasionally distorted by the refraction of radio waves by the fluctuating ionosphere, reminiscent of viewing the sun on a rippled water surface. Such distortions are especially evident in the early moments, when the video begins at sunrise. Credit: CG Yu

Technical intelligence and importance

„Scientifically, this is a unique opportunity to study the Sun’s extended corona with the highest possible resolution at these wavelengths, using the Moon’s limbs as a moving 'knife tip’ to increase the effective angular resolution,” says Bin Chen, solar astrophysicist and associate professor. New Jersey Institute of TechnologyCo-leads OVRO-LWA’s research on the Sun.

The October 14 solar eclipse recorded by the Owens Valley Radio Observatory is approaching maximum eclipse. Credit: Sijie Yu/NJIT

Advances in OVRO-LWA

OVRO-LWA completed a major upgrade this year with funding from the National Science Foundation. The telescope can now scan the sky faster than other radio telescopes operating at frequencies below 100 MHz. Managed by OVRO Director and Caltech Professor of Astronomy Greg Hallinan, the OVRO-LWA project involves collaboration with several institutions. The array continuously detects radio waves in the sky, monitors coronal mass ejections from nearby stars, searches for the magnetic fields of exoplanets and conducts multispectral studies of our Sun, providing insights into the early universe.