# Astronomy

Astronomy is an infinitely captivating subject and the oldest of the natural sciences. It is one of the few areas of science that amateurs can assist professionals and directly contribute to science. Astronomy is the scientific study of the contents of entire Universe, stars, planets, comets, asteroids, galaxies, and space and time, as well as its history. If you're starting out in Astronomy and looking at the sky at night, the contents of this site will guide you through what you can see at night as well as equipment advice, observation tips and tutorials. The astronomy articles cover the types of objects you can see and illustrate some basic astronomy concepts which are important to learn. You can also find several astronomy DIY projects which you can build yourself.

Visual magnitude scale measures relative brightness of objects in the night sky. It has many uses, including calculating distance to stars.
- 21st Apr, 2008

Sidereal time is a method astronomers use to locate objects. Using sidereal time its possible to point a telescope to an object in the sky.
- 17th Apr, 2008

Angular size is a geometric concept and a key astronomical metric. We look at how angular size measured and what arcminutes & arcseconds are
- 17th Apr, 2008

A look at the ways which astronomers measure distance in space covering parallax, distance modulus, variable stars, supernova and redshifts.
- 17th Apr, 2008

We will look at how to locate objects using Right Ascension and Declination coordinates and what the Celestial Sphere are ecliptic are.
- 4th Apr, 2008

Johannes Kepler discovered a link between distance from the Sun and a planets orbital period. This became Kepler's Laws of Planetary Motion.
- 19th Mar, 2008

Hipparchus first calculated the how far away is the Moon in 190BC using a simple method involving trigonometry and was accurate to 1,000km!
- 19th Mar, 2008

How large is the Earth, and how do we know that? Greek mathematician Eratosthenes calculated the size of the Earth in 200BC with a stick!
- 19th Mar, 2008

Cosmology is the study of the history, structure, and dynamics of the universe including how the universe started and how it will end.
- 22nd Dec, 2007

The IAU system of constants defines a system of astronomical units for length, mass and time, and also includes astronomical constants.
- 14th Jul, 2007