Asteroid day leaves an impact
More than 180 years ago, the skies above Tasmania were illuminated by a sight which caused consternation.
On March 10, 1843, the Courier Newspaper reported that, "[T]he inhabitants of Van Diemen's Land ... were astonished on Saturday evening last, soon after sunset, by the phenomenon of a brilliant streak of light, extending several degrees upwards in the western portion of the horizon, for the sudden and beautiful appearance of which everyone was at a loss to conjecture."
Now designated C/1843 D1, the Great Comet of 1843 was rare in that it was bright enough to be visible to the naked eye — the vast majority of comets pass through the solar system inconspicuously and are only observed by astronomers.
With an estimated orbital period of between 600 and 800 years, C/1843 D1 is suspected to be a member of the Kreutz Sungrazers, a family of comets which include the Great Comet of 1882 and Comet Ikeya-Seki, which was first observed in 1965.
The Colonial Times Newspaper of March 14, 1843 reported that: "[M]any people will not believe that it is a comet, the principal reason being this — that if a comet were so close to the earth as this meteor evidently is, we should stand a very good chance of being well roasted."
Captain Walter Synnot was so awestruck by the sight of the Great Comet of 1843, that he painted its appearance over Launceston's Cataract Gorge in a work held by the Allport Library and Museum of Fine Arts.
The Great Comet of 1843 is not Tasmania's only encounter with extraterrestrial space objects.
In 1972, geologist Ramsay Ford discovered a 1.2km-wide suspected meteorite crater in the FranklinGordon Wild Rivers National Park on Tasmania's West Coast.
Ford had been searching for the origins of 'Darwin Glass', an unusual glass material which had been collected over a 410 square kilometre area of the State.
Darwin Glass is suspected to have been formed in the fiery hot temperatures generated by the impact of a meteorite 820,000 years ago.
Organic compounds from plants were trapped in the glass, which some scientists believe could be evidence in favour of panspermia — the theory that life can be distributed from planet to planet.
The Queen Victoria Museum and Art Gallery's Senior Planetarium Officer Chris Arkless said scientists estimated that up to 50,000 tonnes of extra-terrestrial material entered the earth's atmosphere each year.
"Most of this burns up in the atmosphere, but some material — estimated to be over 5000 tonnes per year — reaches the ground as meteorites.
"There are two main classes of objects that are the sources of what we see as meteors flashing across the sky. "
Comets — like the Great Comet of 1843 — are mostly composed of ice, gas and dust that orbit around the sun.
"Asteroids are more solid objects composed of rock and metals.
Both comets and asteroids are leftover from the formation of our solar system, and have had significant impacts to life on Earth such as seen in the Cretaceous - Paleogene extinction event that wiped out the dinosaurs 66 million years ago."
Today marks Asteroid Day, which is observed by the United Nations annually on June 30, and which is designed to educate the public on the risks of asteroid impacts.
Mr Arkless said the QVMAG's Southern Skies exhibition at the Launceston Planetarium contained samples of Darwin Glass and meteorites.
"Along with the long-running Southern Skies exhibition, the Queen Victoria Museum and Art Gallery is currently showing Australia in Space in the former Phenomena Factory area," Mr Arkless said.
"Australia in Space is a fantastic exhibition which explores the unique challenges and opportunities faced by humanity when it comes to operating in space.
"We're also currently upgrading software and hardware in the Launceston Planetarium, which will allow us to link with other Planetaria across Australia and the world, and which will bring some new experiences for people when the Planetarium re-opens to the public next week.
"No matter if you're interested in asteroids, rockets or telescopes the Queen Victoria Museum and Art Gallery has something for you, and I encourage people to come along and check out these wonderful exhibits."
Issued 30 June 2023.