Week 1 - Part 1 Flashcards
Astronomy is defined as the study of the ………….. that lie beyond our planet Earth and the ………….. by which these ………… interact with one another.
objects / processes / objects
Science is not merely a body of knowledge, but a …………. by which we attempt to understand nature and how it behaves. This ……………… begins with many observations over a period of time.
method
From the trends found through observations, scientists can ……… the particular phenomena we want to understand. Such …………. are always approximations of nature, subject to further testing.
model
ancient astronomers constructed a model (partly from observations and partly from philosophical beliefs) that Earth was the center of the universe and everything moved around it in circular orbits. At first, our available observations of the Sun, Moon, and planets did fit this model; however, after further observations, the model had to be updated by adding circle after circle to represent the movements of the planets around Earth at the center. As the centuries passed and improved instruments were developed for keeping track of objects in the sky, the old model (even with a huge number of circles) could no longer explain all the observed facts.
what can astronomers do when our laboratory is the universe? It’s impossible to put a group of stars into a test tube or to order another comet from a scientific supply company.
As a result, astronomy is sometimes called an …………. science;
- observational*
- we often make our tests by observing many samples of the kind of object we want to study and noting carefully how different samples vary.*
Much of astronomy is also a …………… science—meaning that what we observe has already happened in the universe and we can do nothing to change it.
historical
how many kilometers are there in a light-year?
Light travels at the amazing pace of ………….. kilometers per second (km/s),
which makes a light-year ………….. kilometers.
3 × 105
9.46 × 1012
We begin at home with Earth, a nearly spherical planet about ………….. kilometers in diameter
13,000
The Moon’s distance from Earth is about ……… times Earth’s diameter, or approximately ………….. kilometers, and it takes about a month for the Moon to revolve around Earth. The Moon’s diameter is ………….. kilometers, about one fourth the size of Earth.
30 / 384,000 / 3476
Light (or radio waves) takes ………… seconds to travel between Earth and the Moon. If you’ve seen videos of the Apollo flights to the Moon, you may recall that there was a delay of about ……. seconds between the time Mission Control asked a question and the time the astronauts responded. This was not because the astronauts were thinking slowly, but rather because it took the radio waves almost ……… seconds to make the round trip.
1.3 / 3 / 3
Earth revolves around our star, the Sun, which is about …….. ……….. kilometers away—approximately
150 million
We call the average Earth–Sun distance an ……….. ………. because, in the early days of astronomy, it was the most important measuring standard. Light takes slightly more than 8 minutes to travel 1 ………… ………..,
astronomical unit (AU)
the Sun is about …….. ……….. kilometers;
1.5 million
It takes Earth 1 year (3 × 107 seconds) to go around the Sun at our distance; to make it around, we must travel at approximately ………. ………… per hour.
110,000 kilometers
A planet is defined as a body of ………… ………… that orbits a star and does not produce its own light.
significant size
List the 8 Planet in our solar system in order
- Mercury
- Venus
- Earth
- Mars
- Jupiter
- Saturn
- Uranus
- Neptune
