Translating astronomy jargon for the average everyday stargazer
IN EVERY line of work there is some form of jargon we use to communicate.
In astronomy it’s no different. So what are the meanings, for instance, of dark skies, light pollution, good seeing, twinkling and NGC?
DARK SKIES: Means just that. A night sky not affected by the glow of street, residential and commercial lighting (light pollution) beaming up into the night sky as known over large towns, cities and suburbs.
Dark sky conditions allow one to see the Milky Way band and faint stars clearly. A really dark sky is away from civilisation, where it’s so dark one can hardly see a hand or the ground.
That’s why professional astronomers choose mountain tops for large telescopes to carry out serious research of the cosmos.
The only organisation that is trying to save what dark sky sites we have left is the International Dark Sky Association, a voluntary body of professional astronomers and lighting specialists based in Tucson, Arizona, who for the past 31 years have assessed and awarded more than 100 dark sky awards for parks, reserves, sanctuaries and a community.
The IDA has three levels: gold, silver and bronze.
Each of these are based on a sky quality meter reading of measuring the square arc second of the stars under a dark sky canopy and the faintest star magnitude to be seen with the eye.
From my South Burnett Dark Sky Survey carried out over the past two years, the Bunya Mountains, Boondooma Homestead, BP and Boondooma Dams and Moffatdale fit a gold level, while Murgon, Nanango and Wondai silver and Kingaroy bronze, as the town has too much light pollution to get a higher award.
GOOD SEEING: Is a term used by astronomers on a scale of one to 10 to judge the steadiness and clarity of an image as seen in a telescope.
The higher the number, the steadier the sky is, allowing finer lunar and planetary detail to be seen at high magnification in a telescope and vice versa.
The best time is autumn/ winter when the skies are clearer, stable and colder.
Average seeing in autumn/ winter/spring is eight to nine and summer a seven.
TWINKLING: Is starlight being distorted as it passes through Earth’s atmosphere, bouncing off smoke, dust and water particles.
On those nights it’s not good to do any astro photography or high magnification observations of bright stars, the moon or a bright planet.
NGC: Means New General Catalogue, which is the official listing of thousands of galaxies, nebulas, star clusters and quasars.
Drawn up by John Louis Dryer in 1880, the NGC has been in use since by astronomers and in astro-databases worldwide.
If you want to book a night at the observatory, email [email protected]pond.com, phone 0427 961 391 or visit the website, www.kingaroyobservatory.com.
TERMINOLOGY: Dark sky places, nocturnal ecology and species need to be protected from light pollution.
DARK SKIES JAMES BARCLAY