Total eclipse of the Sun in Western Australia

BY RACHEL RAYNER (CSIRO)

On 20 April, a very small part of Australia –Ningaloo Reef in Western Australia – was privileged to witness a rare hybrid solar eclipse.

The limited viewing access did not hamper the rest of Western Australia from celebrating this rare phenomenon, with astronomy events encouraging young and old to look up. CSIRO was a sponsor for both Astrotourism WA’s Eclipse Discovery Tour, where regional communities held stargazing events featuring speakers from the field of astronomy (including SKAO and CSIRO staff), and for the inaugural Ancient Lands Under Brilliant Skies festival, held across two days in the lead up to the eclipse, where CSIRO and SKAO staff met local people and visitors to the region.

A hybrid solar eclipse involves both a total eclipse and annular eclipse. An annular eclipse is where a narrow bright ring forms around the Moon when it covers the Sun. This is often called the “ring of fire”. In a total eclipse, the Moon appears to completely block the Sun so that only the solar corona (the “crown” of light that is emitted by the Sun) is visible. In April, this all happened over a very short period of time, with the hybrid process taking about a minute. Although most of the country saw only a partial eclipse, this was the first time a solar eclipse of any sort had been visible in Australia since 2012.

The eclipse’s path of totality was nearly 800 km away from Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radioastronomy Observatory, home to the SKA-Low telescope and one of its precursors, CSIRO’s ASKAP radio telescope.

The ASKAP team took the opportunity to explore interplanetary scintillation during the eclipse. The partial coverage of the Sun visible on Wajarri Country allowed the telescope to better observe how solar winds can cause distant galaxies to twinkle, distorting the signal. By analysing the solar wind more closely, researchers can get more accurate data on distance galaxies.