Learn the basics of astronomy with historical background and an introduction to the basic astronomy concepts, details about planets, satellites, asteroids, comets and meteors. Also learn the history of Astronomy from its origins in the religious, mythological, and astrological practices of prehistory through to modern astronomy.


Sidereal Time, Civil Time and Solar Time
17th April 2008Astronomy
There are several different systems for measuring Time. Civil time is the system we are all familiar with, however, astronomers use a different system - sidereal time which is measured with reference to background stars in the sky, as opposed to the Sun.
What is Angular Size?
17th April 2008Astronomy
You may have heard the terms arc-minute and arc-second mentioned on the TV, magazines or other websites. These are the units of measurement for angular size used in modern astronomy. Angular size is used to describe the dimensions of an object as it appears in the sky.
Parallax, Distance and Parsecs
17th April 2008Astronomy
In Astronomy, parallax is a method used to determine the distance to the closest stars. This technique for measuring astronomical distances is very important because it is a geometric method and independent of the object being observed.
The Celestial Sphere - Right Ascension and Declination
4th April 2008Astronomy
The most fundamental property that any astronomer needs to know is our place in the heavens and the position of astronomical objects that lie on the surface of the celestial sphere. We will look at the ecliptic and how to locate objects using Right Ascension and Declination.
Kepler's Laws of Planetary Motion
19th March 2008Astronomy
In 1609, a German mathematician by the name of Johannes Kepler discovered a simple relationship between the distance from the Sun and a planet's orbital period. This relationship became the foundation for Kepler's laws of planetary motion.
How far away is the Moon?
19th March 2008Astronomy
How far away is the Moon? Hipparchus first calculated the distance in 190BC using a simple method involving trigonometry and was accurate to 1,000km!
How Large is the Earth?
19th March 2008Astronomy
How large is the Earth, and how do we know that? It was the Greek mathematician and astronomer Eratosthenes who first calculated the size of the Earth, and he did it in 200 BC with a stick!