Studying the Skies

Constellations and Coordinate Systems

When we look at the night sky, we see more than just points of light.
We see patterns, and we have a natural tendency to organize things.
We don't like chaos, so we try to make order out of disorder.
Therefore, the constellations emerge, at least in our minds, as
patterns of stars in the night sky resembling animals, people, or objects.

To view your sky's stars now, or to view your sky tonight, go to John Walker's Your Sky - you choose the location and time.

See Downloads for star charts you can install on your computer.

1. What are Constellations?
2. Movements in the sky
3. Stellar
   Coordinate Systems
4. The Ecliptic (& its significance)
5. Distances in space
6. Examples of Constellations
7. Tests

 Outline Page

The Movement of things in the Sky

Watch the constellations throughout the night. What do you see them do?

They seem to move from east to west
                       (as does the sun through the day),

WHY? Because...

The earth is rotating on its axis, once every day,

and so rotating under the stars.
 

...... from our perspective, they are what moves, not us,
just like the sun moves all the way from east to west each day,

but, the reality is that we are moving under them.

One of the things you need to know how to do is to find stars and other celestial objects consistently and easily.

Go to this page on Coordinate Systems to read a tutorial on how to refer to where celestial objects are to be found.

Also on this page is a special link to the use of a Planisphere, an easy-to-use star chart that can be adjusted for any time and date.

Then, be sure to come back to this page to continue, or take the Coordinate Systems test before you take the Constellations test, if you prefer.

The Ecliptic

What is the ecliptic?

You will see this term from time to time.

Note that it is a different word than

Eclipse, which refers to the covering of a celestial object by the shadow of another (usually for us a Solar or Lunar eclipse), and

ellipse, which refers to an oval (not quite circular) shape, especially referring to the shape of the orbits of the planets around the sun.

The ecliptic is, most simply, the path the Sun takes through the sky from our point of view on Earth, or the plane of the Earth's orbit around the sun, which is the same path.

WHAT IS THE SIGNIFICANCE OF THE ECLIPTIC?

During the day you can't see much other than the sun in the sky, but if you were an ancient sky watcher, you watched what constellations were present where the sun was soon to rise in the morning, and you watched what constellations were present near where the sun had set at night.

Over time, you would have noticed that the particular constellations changed, but that after a year they were the same again.

These particular constellations became the Zodiac. The constellations of the zodiac, therefore, are those the sun moves through, and therefore are those that lie on the ecliptic.

Why did you care?

Because, you also noticed that certain stars or constellations were prominent at planting time, and at harvest, and during religiously significant times. EVERY year, like clockwork! That's why you became powerful!

Information is power, and you had information that meant life or death!

Links for Ecliptic

• Tutorials for Astronomy

•  "From Stargazers to Starships"

• Cornell U.

• Orbits and the Ecliptic Plane-Georgia State U.

• Mayan Astronomy

How Far Away are the Stars?

Let's look at the Big Dipper and Orion for a start. How far away are the stars really that make them up?

Go HERE (then scroll down) to note the relative distances to stars in the Big Dipper, and HERE (click on 2.2 and scroll down to note the relative distances to stars in Orion. I think this is the clearer of the two).

Now go to the Star Distances page, then come BACK here to continue.

Visit:

• The Constellations and Their Stars
• CONSTELLATION PHOTOS
• Classic Star Atlases
• Research the History of the constellations.

Examples of Constellations...