New Page 1

On this page I would like to talk about some of the basics the beginner needs to know.

MAGNITUDE

How bright are the objects in the sky? The method astronomers use to assign a brightness to the objects in the sky is called "magnitudes". This system was developed in the second century BC by the Greek astronomer Hipparchus. The brightest stars have an apparent magnitude of 1 and the faintest that can be seen have an apparent magnitude of 6. The rest of the stars are scattered somewhere in between. Objects that are brighter than magnitude 1 are rated in fractions and negative numbers such as the full moon with a magnitude -13 and the sun with a magnitude of -27. The reason you need to know about magnitudes is so you will be able to determine if the objects you want to view in your telescope are within your range.

DEEP-SKY OBJECTS

The things you will want to look at first with your new telescope will be the moon and planets. But eventually you will want to look at deep-sky objects. Deep sky-objects are stars, nebulae, star clusters, galaxies and basically all things outside of the solar system. The best ones to start with are the 110 Messier Objects (M1 through M110). The list was composed in the late 1700's by the French astronomer Charles Messier who spent his life hunting for comets. The way to find a comet is to look for a fuzzy object in the sky and then check the same object later to see if it has moved. This is what Messier did, but to keep from viewing the same non-comet objects over and over, he made a list of objects to avoid. He had hoped to be remembered by history for the comets he discovered but became more famous for his list of objects to avoid.

LEARN THE SKY

About the only things you can find without knowing your way around the sky are the sun and moon. For all other objects you need to know the basics. The first thing you need to learn is the major stars and constellations. If you buy a telescope on an equatorial mount you have to know Polaris, the north star. If you can find the big dipper, the two stars that form the front of the cup point to the north star. One thing that makes the north star easy to spot is there no other bright stars near it. After finding the north star, use it as a reference point to start finding the constellations. There is a book by the National Audubon Society called "field Guide to the night sky" that is a great aid for learning the constellations. It gives you diagrams of the sky at different times of the year and even gives you the pronunciation of the constellations. This book is also great for teaching all the things someone new to astronomy needs to know. It is also inexpensive.

There is a computer program called "SkyChart III" that has a free demo download. It is an excellent program, especially for the beginner. It uses the time and date of your computer to give you a current view of the sky so you know what's available for viewing. It's also a great tool for learning the sky.

COORDINATES

If the earth was made of glass with a big light inside it and the longitudes and latitudes were drawn with big dark lines, turn the light on and the lines reflected on the sky would be the celestial coordinates. The north-south coordinates, which would be the same as latitude on earth, are called declination which are measured in degrees, minutes and seconds. Above the equator the degrees begin with a N or + and below the equator the begin with a S or -. The east-west coordinates, which is like earth's longitude, are called right ascension and are measured in hours, minutes and seconds instead of degrees west or degrees east. Since the earth is divided into 360 degrees, one hour would equal 15 degrees.

The celestial meridian is a line that goes from the north overhead to the south and divides the east and west.. the right ascension coordinate that is passing through the celestial meridian at any given time is known as the sidereal time. The tracking motors on telescopes are set to sidereal time which is very similar to our 24 hour clock except, 24 hours in sidereal time is about 3.9 minutes shorter than a regular clock. This is because of the earths orbit around the sun. The earth has to turn 3.9 minutes more than one rotation in order to catch up to the sun. 24 hours in sidereal time is exactly one rotation of the earth.