Observing the Sky: The Birth of Astronomy

In modern times, like state boundaries on a map, the sky is separated into ___ carefully delineated areas called _______.

88; constellations

What is the celestial sphere?

A useful mental model for understanding how the stars move through the sky.

If the star directly above you stays fixed all night and the stars do not rise or set, where are you?

At one of the poles

What causes the stars to move in circles across the night sky over the course of a night?

Because the Earth is constantly rotating the stars appear to rotate around it in the opposite direction.

Which planets (other than Earth) can be seen using only the naked eye?

Mercury, Venus, Mars, Jupiter, and Saturn.

Why do stars appear to twinkle when we look at them from Earth?

The air in Earth's atmosphere is unstable and changes the direction of the light that passes through it several times per second. As a result, we on the surface see changes in brightness that we call twinkling.

Why is it that some stars appear to have color while other simply appear to be white?

The color receptors in our eyes are not sensitive enough to detect color in fainter stars and as a result only the brightest stars in the sky appear to have color.

Why do some stars appear brighter than others as seen from the same spot on Earth?

The inherent brightness of each individual star differs. Some stars are closer to the Earth than others.

Why do the planets not appear to twinkle like stars do?

They are closer to Earth and as a result appear larger, meaning their light is not as distorted as it passes through the atmosphere.

Light pollution has negative effects not only on stargazing but also on the behaviors of certain bugs and other animals. What action is necessary to decrease light pollution in a city?

Use a different type of lighting that directs light towards the ground.