Coordinate Systems

There are different coordinate system used in astromomy.

The  main one's - for finding things in the night sky

 are  Altitude / Azimuth

and

Right Asenction / Declination

Altitude and Azimuth system

This is the most basic system for finding objects in the night sky

You locate objects in the night sky by using alitude and azimuth angles.

Altitude is the measure of how many degrees an object is above the horizon. Azimuth is a measure in degrees how far along the horizion  from true north the object is.

For example if the planet jupiter is at 45 degrees Altitude and 200 degrees Azimuth, then

Look for the north star called polaris, then look for the horizon below it. Then  measure 200 degrees around the horizon and stop. You then look 45 degrees above the horizon. If you did everything ok, you would spot jupiter. It can be trick to locate stuff this way

A guide on measuring the degrees around the horizon.

Facing North is 0 degrees Azimuth

If you face north, then south or 180 degrees Azimuth is behind you.

Facing north , east is on your right shoulder, and is a 90 degrees Azimuth

 Facing north, west is on your left shoulder, and is 270 degrees Azimuth.

A guide for altitude

The horizon is 0 degrees altitude.

Standing up, 90 degrees Altitude is the area of sky, right over your head.

So then 45 degrees Altitude is halfway between the area of sky over your head, and the horizon.

Right Ascention and Declination

This is a system of measurement found on a telescope with an equatorial mount.

It's 0 degrees or 0 Hours Right Asenction ( R.A ) is the point where the sun cross the celestial equator in the spring. Right Ascention is a measure of angles starting at that point around the night sky until, it reaches that point again.

Declination is the measurement of angles from the celestial equator to the north or south poles.. The celestial equator, is the imaginary line that pass through earth's equator into the night sky above it. The north or south poles are the area of sky above the earth's ploes.

In order to use the right ascention and declination system, you have to align your telescope with the area of sky near polaris.

Other coordinate systems