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Published 8th November 2010 by

Astronomy is an endlessly fascinating field, the oldest of the natural sciences, and one of the few areas of science that amateurs can assist the professionals and contribute to science.
Introduction to Astronomy Series
  1. Introduction to Astronomy
  2. The Celestial Sphere - Right Ascension and Declination
  3. What is Angular Size?
  4. What is the Milky Way Galaxy?
  5. The Astronomical Magnitude Scale
  6. Sidereal Time, Civil Time and Solar Time
  7. Equinoxes and Solstices
  8. Parallax, Distance and Parsecs
  9. Luminosity and Flux of Stars
  10. Kepler's Laws of Planetary Motion
  11. What Are Lagrange Points?
  12. Glossary of Astronomy & Photographic Terms
  13. Astronomical Constants - Some Useful Constants for Astronomy

This tutorial series covers the basics of modern astronomy as a science, including the structure and evolution of planets, stars, galaxies, and the Universe as a whole. We will look at observational astronomy, the magnitude scale, spectroscopy and celestial mechanics.

What is Astronomy?

Astronomy as a science began tens of thousands of years ago by tracking the motion of the Sun, Moon, planets, and stars. It has since developed into a sophisticated study of the fundamental laws of nature governing these phenomena.

The first observations of the heavens were conducted by our early human ancestors. Historical records of astronomical measurements date back as far as Mesopotamia nearly 5000 years ago, with later observations made by the ancient Chinese, Babylonians, and Greeks.

1675 image of a Chinese astronomer with an elaborate armillary sphere.

1675 image of a Chinese astronomer with an elaborate armillary sphere.


Astronomy is more than simply a mapping of stars and planets into outlines of gods and magical creatures. It is the scientific study of the contents of entire Universe, stars, planets, comets, asteroids, galaxies, and space and time, as well as its history.

In the Age of Antiquity, astrometry was the main occupation of astronomers. There was some degree of interest for astronomy from the general public as well, since they believed that the positions of celestial objects influenced events that took place on Earth. Astrology, which is the art of predicting future events based on such observations, was considered a branch of astronomy and formed an integral part of the astronomer's work for several centuries.

Branches of Astronomy

There are two main branches of astronomy - optical astronomy (the study of celestial objects in the visible band) and non-optical astronomy (the use of instruments to study objects in the radio through gamma-ray wavelengths). Non-optical is sorted into wavelength ranges, such as infrared astronomy, gamma-ray astronomy, radio astronomy, and so on.

Within these branches there are many sub-branches of astronomy. These include solar, planetary, stellar, galactic, cosmology to name a few.

Meet a Few Pioneers of Astronomy

Over the centuries there have been countless innovators in astronomy, people who contributed to the development and advancement of the science. Today there are more than 11,000 trained astronomers in the world dedicated to the study of the cosmos.

Where to Start in Astronomy

If you're starting out by simply looking at the sky at night, I have an excellent observational astronomy tutorial series that takes you through what you can see at night, how to observe targets, telecope selection as well as some equipment advice.

In the first tutorial of this series we will look at the celestial sphere and how we locate objects in the sky.

Amateur astronomers also play an important role in research. The most serious amateurs actively participate in the study of variable stars, the discovery of new asteroids or comets, and other exciting astronomical work.

Artists concept of the Milky Way galaxy

Artists concept of the Milky Way galaxy

Nick Risinger

Tutorial Series

This post is part of the series Introduction to Astronomy. Use the links below to advance to the next tutorial in the couse, or go back and see the previous in the tutorial series.

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