Some Useful Definitions

There are a few terms which we use a lot when trying to understand the sky:

Latitude is a way of describing where you are on the Earth between the equator and the poles. If you're latitude is 45° North, then you are halfway between the equator (latitude = 0°) and the north pole (latitude=90°).

The horizon is the plane which defines the half of the sky that you can see.

Altitude is the angle between the object you are looking at and your horizon.

The ecliptic can refer to many slightly different ideas which all relate to the Earth's orbit. The plane in which the Earth goes around the Sun is called the ecliptic. The ecliptic is also an imaginary line in the sky along which the Sun appears to travel as the Earth goes around the Sun. The path of the ecliptic determines the zodiacal constellations; they are all constellations through which the Sun appears to move as the Earth goes around the Sun.

You might also be interested in:

Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Native American Astronomy

People from Asia crossed the Bering Strait into North America. These people were first in this new land and so they are known as Native Americans. Over time, these people broke into tribes (as seen on...more

Archeoastronomy

"The movements of the heavenly bodies are an admirable thing, well known and manifest to all peoples. There are no people, no matter how barbaric and primitive, that do not raise up their eyes, take note,...more

The Stones of Carnac

The stones of Carnac, France, are probably the most famous stones markings outside of those found at Stonehenge in England. There are many, many stones at Carnac. And these stones are very old too, the...more

The Cairns of Clava

Not too far from Loch Ness, there lies three giant tombs made of stones. They are called the Balnuaran of Clava. The Balnuaran of Clava, giant tombs encased in stone, can be found close to Inverness in...more

Cuzco

Cuzco is located in Southern Peru. It is the ancient capital of the Inca Empire. It is the oldest, continuously occupied city in the Americas. In ancient times, Cuzco was the ceremonial capital and hub...more

The Stones of Fossa

The stone structures of England and France are very famous. In Italy, you'll also find standing stones, stone rings, and stone tombs. An example of these stone structures is in Fossa, Abruzzo, in Italy....more

Kepler's 2nd Law: The Speeds of Planets

Kepler's second law he again discovered by trial and error. Kepler realized that the line connecting the planet and the Sun sweeps out equal area in equal time. Look at the diagram to the left. What Kepler...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA