The "Slow" 2019 Whale Season and the Meteor Airburst in Southern Australia

Direct Migration Path: In May, Southern Right Whales are actively moving from the sub-Antarctic feeding grounds (40°S–60°S) toward the coastal nurseries of Warrnambool (Logans Beach) and the Great Australian Bight. The May 21 airburst happened exactly when the lead females would have been approaching the coast.

The "Adelaide Fireball".

2019, May 21. Large Airburst. Time: ~10:30 PM local time, 13:12UT. Energy/Size: It was estimated the object was roughly the size of a small car, weighing in at between 20 to 40 tonnes. Altitude: 31.5 km. Velocity: 11.5 km/s. Impacted 440km south of Adelaide in Great Australian Bight or 430 km east of Warrnambool in Victoria. It was 260 km from the nearest coastline in South Australia. Energy: e (Radiated Energy in Joules) = 65.6e10. Impact yield 1.6 kt or equivalent to 1,600,000 kg of TNT. CCTV from Safety Beach on Victoria's Mornington Peninsula showed a huge ball of light falling from the sky and illuminating Port Phillip Bay. It was also caught on dashcam from Adelaide. At Horsham it was described as “a huge bright white light”. CNEOS data and infrasound arrays recorded a significant atmospheric disruption. The meteor moved from north to south, flaring green and then orange. It was visible from Adelaide (SA) all the way to the Gippsland coast (VIC). Acoustic Impact: Residents across South Australia and Western Victoria reported a "massive boom" that made houses and the earth "shake visibly." This indicates a low-altitude airburst or a significant sonic boom from a large fragment.

Because stony meteorites are more likely to explode violently in the mid-to-lower atmosphere, they release their kinetic energy as a massive pressure wave (infrasound) all at once. If the airburst occurred over the shelf or near the coastline (fragments were suspected to have landed in the ocean), the resulting infrasound would have been intense. For a species that relies on low-frequency sound for navigation and social cohesion, a 1.6 kt-equivalent "thump" could have acted as an acoustic deterrent. Geographic Mapping of the bolide's trajectory (North to South over SA/VIC) means the pressure wave would have propagated directly into the Great Australian Bight and the Bonney Upwelling (a major whale corridor).

In 2018 South Australia recorded 789 individuals. In 2019, the year of this major bolide, the numbers dropped to 577. This ~27% drop in sightings is often attributed to natural "calving cycles," but the presence of a car-sized meteor exploding over the migration corridor just as it started provides a strong physical alternative. It suggests the whales didn't just "fail to show up"—they were likely deterred or disoriented by the acoustic impact.

The Southern Right Whale population has still not recovered from this event.

There was a large airburst in 2014 off Antarctica, one in 2015 in the migration corridor (SRW population plateaued), two in 2017, before the 2019 event. Humpbacks go where they want when they want; they adapt, SRW do not. These whales are more fragile and favour routine and regular habitats far more than humpbacks.