Identifying Objects in the Night Sky and Effect of Light Pollution

Identifying Objects in the Night Sky

Stars are pinpoints of light that twinkle and tend to maintain a constant relative position to each other. They move across the sky due to Earth’s rotation.
Planets do not twinkle and noticeably move against the backdrop of stars over time. The visible planets include Mercury, Venus, Mars, Jupiter, and Saturn.
Constellations are patterns identified among stars. Recognising these can assist in finding certain stars or celestial events.
The Moon, Earth’s natural satellite, changes its shape or phase over the course of a month, and at certain times is not visible.
Artificial satellites, such as the International Space Station, move predictably across the sky and do not twinkle.
Comets appear as a fuzzy point of light with a distinctive tail pointing away from the Sun.
Meteors or ‘shooting stars’ are brief streaks of light caused by small particles entering Earth’s atmosphere at high speeds. They typically occur randomly but can be more frequent during a meteor shower.
Asterisms are recognizable patterns of stars that are part of an official constellation or made up of stars from several constellations. The Big Dipper or Plough is a well-known asterism.

Light pollution is the brightening of the night sky caused by artificial light sources which obscures the visibility of celestial objects.
Light pollution primarily impacts urban and suburban areas where outdoor lighting is prevalent.
The increased artificial light makes it difficult to see faint stars, nebulae, the Milky Way and other galaxies.
Skyglow is a type of light pollution that is caused by scattered light in the atmosphere, diminishing the contrast between stars and night sky.
Glare is excessive brightness that causes visual discomfort and can obscure the view of celestial objects.
To mitigate the effects of light pollution, astronomers often use filters, or perform observations away from city lights, in places known as ‘dark sky preserves’.
Light pollution not only affects astronomers, but it also disrupts ecosystems and has adverse health effects on humans and wildlife.
International Dark-Sky Association (IDA) works to help reduce light pollution and has designated certain areas as International Dark Sky Places.
Astronomy software can help predict the impact of light pollution on celestial observations, and there are maps available that show light pollution levels worldwide.

Star Magnitude is a term used to describe the apparent brightness of a celestial object, with magnitude 1 being the brightest and each increase in number signifying a decline in brightness.
Light pollution affects visibility of stars of different magnitudes. In areas with high light pollution, only stars of lower magnitudes (brighter stars) may be visible.
In an ideal situation away from all artificial light, an individual can see stars up to the 6th magnitude.
The Naked Eye Limit (NEL) refers to the faintest star visible to the naked eye under optimal conditions, usually taken to be 6th magnitude.