Astronomy Ch. 1-A

Of these which is the closest to us?

The Moon

Light travels 3 x 10^5 meters every second. That number in words is

300,000 meters

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

The Moon

Of these, which is the largest?

The Universe

The location of the Earth in the Milky Way Galaxy is

a little less than 30,000 LightYears from the center

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

an atom

The laws of nature (as determined by scientists)

are constructed from many observations, hypotheses, and experiments

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 Astronomical Unit (AU) as defined by astronomers is

the average distance between the Earth and the Sun

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

230 years ago

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

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

a star

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 space 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

The star that provides energy for life on Earth is

the Sun

A light year is

the distance that light travels in one year

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

two or more atoms