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Here are a few of the more common astronomical terms you'll come across, just to get you started. There are many more defined in the Glossary .
Planet
Just like the Earth! A planet is a sphere of either rock or gas that orbits the Sun. There are nine planets in our Solar System, and the Earth is the third planet out from the Sun. There is a diagram in the book that gives a good overview. There are also a number (actually tens of thousands) of 'minor planets' that move around the Sun, mostly between the orbits of Mars and Jupiter. The Moon and all the planets we see in the sky do not glow in their own right. They are only visible because of reflected sunlight.
Star
Just like the Sun! A star is an enormous sphere of glowing gas that gives off tremendous amounts of light and heat. They shine by their own light caused by nuclear reactions going on deep inside them. It's a testament to the enormous distances between the stars when you realise that the Sun is a relatively average star, while some stars visible in the night sky are tens or hundreds of times larger and brighter, yet in our sky look so faint.
Time
The times used in Part I are in Australian Eastern Standard Time (AEST). AEST is the mean solar time on the meridian of longitude of 150 degrees East. For Australian Central Standard Time (ACST) subtract 30 minutes from the times given. For other time zones make the appropriate adjustments. No adjustments have been made in this book for Daylight Saving, also known as 'Summer Time'. When daylight saving is in force, the time is one hour ahead of AEST. For example, any rise / set time for an object in this book will need to have one hour added to it to get daylight saving time.
Magnitude
The brightness of a star or a planet in the night sky is described as its magnitude (sometimes abbreviated to 'mag.'). The numbers work backwards. The faintest star you're likely to see with the naked eye is about 6.0 magnitude, while the brightest stars are -1.0 magnitude. Planets can be much brighter. Venus, for example, can be as bright as -4.0 magnitude, the full Moon, -12 magnitude!
Twilight
Twilight does not really end until the Sun is 18 degrees below the horizon; this is called 'astronomical twilight'. This happens about 90 minutes after sunset (or before sunrise) and is different from what people would normally call the end of twilight. This would be Civil twilight, which begins or ends when the Sun is 6 degrees below the horizon (about 30 minutes before sunrise or after sunset). Only when astronomical twilight has ended, is the sky considered truly dark (assuming the Moon isn't above the horizon!). But keep in mind that many celestial features can be seen even during twilight; binoculars can also help. The actual time between sunset and end of twilight (and the beginning of dawn and sunrise) does vary with latitude. The further south, the longer the time of twilight. Compare the times of twilights and rise/sets in Part II between Darwin and Hobart.
Culmination
When an object culminates it has reached its highest point in the sky and is generally considered to be the best time to observe it. For the planets, this is normally when they are due north.