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Reading – “The Night Sky”
Read this passage about the night sky and answer the
questions on the back of the page.
THE NIGHT SKY
If you go outside on a clear night and look at the sky, what do you
see? Stars of course. Thousands of them. In fact on a dark
night, you may be able to see about three thousand stars without
the aid of binoculars or a telescope.
WHAT IS A STAR?
Stars are glowing, rotating balls of gas. Even though you may see thousands of stars, you
are only seeing a small fraction of the stars in our universe. Scientists estimate that there are
more than a thousand billion billion stars in our universe! However, almost all of them are
too far away for you to see with your naked eyes. From our perspective on earth, stars
appear as tiny points of light, but of course, they are much, much larger than they seem. A
medium-sized star like our sun could hold more than a million earths inside it! Other stars
such as supergiants may be thousands of times larger than our sun. But the enormous
distance between them and our earth makes tham appear tiny in the night sky.
So what makes a star shine? Hot gases under enormous pressure undergo a process called
nuclear fusion that causes the star to give off energy in the forms of light and heat. Some
stars may reach temperatures of millions of degrees!
STAR COLORS
You can tell the temperature of a star just by noticing its color. Stars with the coolest
surface temperatures are the red. Their temperatures reach about 3,000 degrees Kelvin.
Examples of these are the stars Betelgeuse in the constellation Orion and Antares in the
constellation Scorpio. Yellow stars, such as our sun, are in the middle of the temperature
scale. Our sun reaches 6,000 degrees Kelvin on its surface. Finally, the blue colored stars are
the hottest of them all. Blue stars such as Rigel in the constellation Orion, and Spica in the
constellation Virgo have surface temperatures of up to 25,000 degrees Kelvin.
CONSTELLATIONS
For thousands of years, humans have looked at the night sky and played “connect the
dots.” By connecting stars that appear to be close together, the eighty-eight different
constellations of the night sky have been created. Some famous constellations include
Hercules, the brave son of Zeus, Cassiopeia, the beautiful queen of Ethiopia, Orion, the
brave hunter, and Hydra, the nine-headed serpent. The legends surrounding these
mythological characters are still known to us today.
“The Night Sky” Questions
Directions: Use the
story “The Night Sky”
to answer these
questions.
1. Why can’t you see all the stars in the
universe when you look up at the night
sky?
A. The sky isn’t dark enough.
B. The earth is too big.
C. You could if you could just stay up late enough.
D. Most stars are too far away to be seen with your eyes.
2. What is the process called by which stars create light and
heat?
A. combustion
B. nuclear fusion
C. burning
D. evaporation
3. What is the scale used to determine
the temperature of a star?
A. Celsius
B. Kelvin
C. Fahrenheit
D. heat index
4. Which is the hottest of the stars?
A. a red supergiant
B. a medium-sized yellow star
C. a blue star
D. They are all the same temperature.
5. How many constellations are there in the night sky?
A. 25
B. 68
C. 88
D. 104
Some information taken from Ranger Rick’s NatureScope “Astronomy
Adventures”, McGraw-Hill Publishers, copyright 1989.