Download Benchmark lesson

Name
Date
Benchmark Mini-Lessons
Chapter 16, Lesson 1
What is the history of astronomy?
Many ancient civilizations tracked the motions of objects in the
sky. They used the predictable movements to track time. Over the years,
people began to make tools to help them study the planets and stars.
As technology got better, the tools people used to study astronomy got
better too.
One of the most important tools invented to study the sky was
the telescope. Galileo Galilei (1564–1642) was the first to use a
telescope to study the sky. Over time, as telescopes became a lot
larger and much more powerful, scientists could see deeper and
deeper into space.
Over the years, scientists were able to see far more than
Galileo ever did, but they wanted to see more. Eventually, scientists
could not make new telescopes that could give them a better view
of space than what they saw with the telescopes they had already
developed. The reason was simple—Earth’s atmosphere. The atmosphere
distorts, or changes, the way things look. That is why scientists around
the word wanted to put a telescope in space. The images formed by the
space telescope would not be distorted by Earth’s atmosphere.
The scientists’ dream came true when the Hubble Space Telescope
was sent into space from Cape Canaveral, Florida, in 1990. It remains
in space today, traveling about 600 kilometers (380 miles) above Earth.
It continues to send impressive images to scientists.
What problems does Earth’s atmosphere cause for scientists trying to
study space?
Florida Science Benchmark: SC.H.3.2.1 Annually Assessed Benchmark
The student understands that people, alone or in groups, invent new tools to solve problems and do work
that affects aspects of life outside of science.
62 Chapter 16 • Lesson 1
FCAT Benchmark Mini-Lessons
© Pearson Education, Inc. 5
1
Name
Date
Benchmark Mini-Lessons
Chapter 16, Lesson 2
What is a star?
Most people living in Florida know that the Sun constantly gives off
a lot of energy. Its energy comes from reaction between the hydrogen
gas and the helium gas that makes up the Sun. During the reaction,
called nuclear fusion, large amounts of energy are given off in the form
of light and heat. Many schools and community buildings in Florida use
this energy to heat water. The energy from the heated water is used to
make electricity.
Compared with the Earth, the Sun is huge. A single sunspot on the
Sun’s surface may be larger than the entire planet we live on. However,
when compared to other stars, our Sun is not very large or very hot.
It is an average star. Some stars are much smaller than the Sun while
other stars can be more than 100 times larger.
The light from our Sun reaches Earth in about eight minutes. The
light from the next closest star to us takes more than four years to reach
Earth. The light from more distant stars may take billions of years to
reach our planet. Because distances in space are so great, scientists
measure the distances between stars in light-years. A light-year is the
distance that light travels in one year. When we look at distant stars,
we are looking billions of years into the past because we are seeing
light that came from the stars long ago.
Nearest Stars
© Pearson Education, Inc. 5
2
Star
Distance (light-years)
Proxima Centauri
4.2
Alpha Centauri
4.3
Barnard’s Star
6.0
Why is our view of the stars a look into the past?
A
B
C
D
As the Earth turns, we lose track of time.
The light from the Sun blocks out the light from other stars.
It takes many years for the light of distant stars to reach us.
There are many other galaxies besides the Milky Way.
Florida Science Benchmark: SC.E.2.2.1
The student knows that, in addition to the Sun, there are many other stars that are far away.
FCAT Benchmark Mini-Lessons
Chapter 16 • Lesson 2
63
Name
Date
Benchmark Mini-Lessons
Chapter 16, Lesson 3
How are stars grouped together?
Did you ever look into the sky and
imagine that the stars made a picture? Many
ancient people thought they saw patterns
in the stars. They named the stars after the
patterns they saw—animals or other figures
that had special meanings to them. These
groups of stars are called constellations. One
constellation you might be familiar with is
Ursa Major. It contains the stars that make up
the Big Dipper.
Different constellations can be seen in
different parts of the world. For example,
Crux, which is also known as the Southern
Cross, cannot be seen from most places in
Ursa Major
the Northern Hemisphere. The Florida Keys
is one of the few places north of the equator where you can see the
Southern Cross. Early explorers in the Southern Hemisphere used this
constellation to help them find their way.
The stars we see in the sky are part of the Milky Way galaxy. A
galaxy is a huge system or stars, planets, dust, and gas held together
by gravity. Earth and its solar system are part of the Milky Way galaxy.
The Milky Way is only one of the billions of galaxies in the universe.
The Milky Way galaxy is a spiral galaxy. Spiral galaxies have a thick
middle. They have spiral arms that spin out from the center. Other
galaxies are elliptical or oval in shape. Some galaxies are irregular
in shape.
What type of galaxy is the Milky Way?
F
G
H
I
© Pearson Education, Inc. 5
3
constellation
spiral
elliptical
irregular
Florida Science Benchmark: SC.E.2.2.1
The student knows that, in addition to the Sun, there are many other stars that are far away.
64
Chapter 16 • Lesson 3
FCAT Benchmark Mini-Lessons