CH 1

A star is 230 light years away. The light we see tonight from that star left it

230 years ago

Light travels 3 x 108 meters every second (after rounding). That number in words is

300,000,000 meters

When the authors of our textbook say that astronomers are like police detectives trying to solve crimes, they are explaining that:

Both astronomers and detectives must test their hypotheses against any evidence that they gather

Of these which is the closest to us? Mars The Moon The Sun The center of the Milky Way The closest spiral galaxy

The Moon

Of these, which is the largest? Earth The Solar System Jupiter The Milky Way Galaxy The Universe

The Universe

The location of the Earth in the Milky Way Galaxy is

a little less than 30,000 LY from the center

A large body in space that consistently makes its own light (instead of merely reflecting another body's light) is called

a star

The smallest piece of an element (like gold or lead) that still has all the properties of that element is called

an atom

The way scientists know that a hypothesis in astronomy is a reasonable description of nature is to

do experiments and observations about the predictions of the hypothesis

Even with the best and largest telescopes, we can't see all the stars in the Milky Way Galaxy, even though these same telescopes can show us other galaxies. Why is that?

dust in the spaces between stars builds up over large distances and blocks the light of stars behind the dustier parts of the milky way

By the term universe, astronomers mean

everything that we can observe

You are on a camping trip, far away from city lights. You look up into the dark night sky, and see lots of stars, some brighter, some dimmer. All the stars you see with your unaided eye are

in the Milky Way Galaxy

The laws of nature (as determined by scientists)

more than one of the above a) are constructed from many observations, hypotheses, and experiments b) apply both on Earth and among the stars d) are often written in the language of mathematics

The Astronomical Unit (AU) as defined by astronomers is

the average distance between the Earth and the Sun

A light year is

the distance that light travels in one year

The natural object (not one that humans built) in space that's closest to Earth is

the moon

For scientists, an element (like gold) is defined by

the number of protons in its nucleus

The star that provides energy for life on Earth is

the sun

All molecules (like molecules of water or carbon dioxide) are made up of

two or more atoms

Which of the following is the Earth NOT located in?

we are located in all: the solar system the Milky Way Galaxy the Local Group of galaxies The Virgo supercluster