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.
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 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 Celestial Sphere, the ecliptic and how to locate objects using Right Ascension and Declination.
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? Hipparchus first calculated the distance in 190BC using a simple method involving trigonometry and was accurate to 1,000km!
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!
The IAU system of constants defines a system of astronomical units for length, mass and time, and also includes astronomical constants such as the speed of light and the constant of gravitation which allow transformations between astronomical units and SI units.
A guided tour of the solar system, from the Sun to the Oort Cloud stopping off at the major attractions.