I apologize, upon further reflection I do not feel comfortable advising students to directly observe the sun without appropriate safety equipment. Looking directly at the sun can cause permanent eye damage.

2. A. Choose the letter of the best answer.
For numbers 1 to 3, use the table below that
presents information about stars A, B, C, and D.
Star Color
A Red
B Yellow
C White
D Blue

3. 1. Which star is the hottest?
a. A b. B c. C d. D
2. Which star is very similar to our sun?
a. A b. B c. C d. D

4. 3. How do stars appear to move in the night
sky?
a. From East to West
b. From North to South
c. From East to West
d. From South to North

5. 4. Stars appear to move in the sky
because
a. The Earth is rotating on its axis.
b. The universe is expanding.
c. The night sky is rotating.
d. New galaxies are formed.

6. 5. If you are located at the North Pole,
where will you see the Polaris?
a. Overhead
b. Just above the horizon
c. Around 45⁰ from the horizon
d. Polaris will not be seen in the North Pole

7. 6. Which constellation is prominently
seen in the sky during summer?
a. Orion
b. Pegasus
c. Hercules
d. Virgo

8. 7. Based on apparent magnitude,
which of the following stars is the
brightest?
a. Alpha centauri
b. Betelgeuse
c. Rigel
d. Sirius

9. 8. Why do stars have colors?
a. It is because of the presence of
oxygen.
b. It is because of the presence of
carbon dioxide.
c. It is because of varied temperatures.
d. It is because of the different
locations.

10. 9. Stars can be found in large groups
throughout the universe. What are
these groups called?
a. Solar system
b. Comets
c. Constellations
d. Asteroids

11. 10. The star Algol is estimated to be as bright
as the star Aldebaran and have approximately
the same temperature as the star Rigel.
Which of the following statement is correct?
a. Algol and Rigel have same color.
b. Algol and Rigel have the same brightness.
c. Allgol and Aldebaran have the same in size.
d. Algol and Rigel have the same brightness
and color.

12. Rigel
Sirius

13. Definition of terms:
 Star – is a swirling, glowing ball of gases.
 Constellation – is a group of stars that has a
shape resembling that of an animal, a
mythological character, or some other
object.
 Galaxy – is a large constellation or large
groups of gases, dust and stars in space held
together by gravity. Type: Elliptical galaxy,
spiral galaxy and irregular galaxy.

14. When we look at the night sky, we
see thousands of stars. In reality,
there are approximately 400 billion
stars in our galaxy, and there are
about 170 billion galaxies. A person
can see only about 3,000 stars on
the average.

15. Characteristics of Stars
Color and Temperature
Brightness and Magnitude of Stars
Sizes of Stars
Distances of Stars
Composition of Stars

16. Characteristics of Stars
Color & Temperature
- Star color ranges from red to blue. The
color of the star indicates its surface
temperature.
- The coolest star is about 2800⁰C at the
surface. These star appear red. The
temperature of the hottest star is about 28
000⁰C or higher. These star appear blue.

17.  Sun – Yellowish, 5500⁰C
Stars that are cooler appear
orange, stars that are hotter than
the sun appear white.

18. Table 1. Color and Temperature of Selected Stars
Star Color Surface
Temperature in
Celsius
Sun Yellow 5,700
Proxima Cantuari Red 2,300
Epsilon Iridani Orange 4,600
Vega White 9,900
Sirius White 10,000
Alnilam Blue 27,000

20. Figure 2 shows the size of the Sun, the closest
star to Earth, as compared to some other
stars that we see at night. As we can see, the
Sun is so small compared to other nearby
stars. Also, Sirius, which appear bigger than
Rigel, is actually very small compared to
Rigel. It appears larger only because it is
closer to us.

21. Characteristic of Star
 Brightness
- The brightness of a star as seen from the
Earth depends on two factors: distance and
the actual brightness (or absolute
brightness) of the star. The star’s
brightness as seen from Earth is its
apparent brightness, apparent brightness
depends on how far away a star is from the
Earth.

22.  Astronomers consider the star’s absolute
brightness when comparing stars. A star’s
absolute brightness is the brightness the
star would have if all stars were the same
standard distance from Earth.

23. Characteristics of Stars
 Sizes of Stars
- Stars varies in size, from huge to supergiants
to tiny neutron stars.
- Astronomers group stars in to five types:
neutron stars, white dwarfs, medium-
sized stars, giants and supergiants.

24.  Neutron stars are the smallest, it has a
diameter of about 16 km.
 White dwarf is about 7300 km, slightly
greater than that of the Earth.
 Medium-sized star is about one-tenth the
diameter of the sun. Sun has 1.35 million
km in diameter.
 Giant star is 10 to 100 times that of the sun.
 Supergiant stars is up to 1000 times the
diameter of the sun.

25. Characteristics of Stars
 Distances of Stars
- Scientist use parallax to determine how far
away a star is from Earth. A parallax is an
apparent change in the position of an object
caused by a change in the position of the
observer.
- The closer a star is to Earth, the greater its
apparent change of position. Very distant
stars seem not to shift position at all.

26.  Scientists express distances between stars in
light years. A light year is the distance that
light travels in one year at a speed of 300 000
km per second (kps). A light year is about
9.5 trillion km or 9 500 000 000 000 km.
 The closest star is Proxima Centauri, 4.2
light years from Earth. Other stars are
hundred of light years away.

27. Characteristics of Stars
 Composition of Stars
- Using spectroscope, astronomers have found that
almost all stars have the same general chemical
make-up. The most element in stars is hydrogen,
the lightest element that makes up 60% to 80% of
the total mass of a star. The second element is
helium, combination of H and He make up about
96% to 99% of stars mass.
- Other elements are oxygen, neon, carbon and
nitrogen.

28. The Polaris
 Polaris, commonly known as North Star, is the
brightest star in the constellation Ursa Minor (Little
Dipper). It is very close to the north celestial pole,
making it the current northern pole star. Because it
lies nearly in a direct line with the axis of the Earth's
rotation "above" the North Pole, Polaris stands almost
motionless in the sky, and all the stars of the Northern
sky appear to rotate around it. In Figure 3, Polaris and
the star trail are seen. Star trail is a type of
photograph that utilizes long-exposure times to
capture the apparent motion of stars in the night sky
due to the rotation of the Earth.

29. Fig. 3 Polaris and
the Star Trail over
Mt. Pulag

30.  In Metro Manila, when you face North,
Polaris, which is 11.3⁰ from the horizon, is
seen at around 15° due to atmospheric
refraction. In some parts of the country (i.e.
Southern Philippines), it would be very
difficult to locate Polaris since star lights
near the horizon are washed out by lights
lit by men, and /or obstructed by man-
made or topographical structures and/or
trees.

31. Fig. 4 Polaris as viewed from the Philippines (Quezon City). To locate
Polaris, face North and locate the Big Dipper. Two stars (Merak &
Dubhe) in the Big Dipper are called pointer stars because they seem to
point to Polaris.

32. Constellation for a certain month:
March Night Sky 9pm

33. June Night Sky 9pm

34. September Night Sky 9pm

35. December Night Sky 9pm

36.  An observer from Earth will be able to see the
stars that are on the night side. The stars on the
same side as the sun cannot be seen because
sunlight overpowers all the star lights.
 During summer in the Philippines, the
constellations of Orion and Taurus are not visible
at night. They will be visible again as the cold
season begins. During this time, Scorpius will not
be seen in the night sky.
 As the Earth revolves around its orbit, the stars
that were concealed by the bright light of the Sun
in the previous months will appear in the night
sky.

38. How Early People Used the Constellations
 While constellations were associated with religion,
they also have practical uses. Before the calendars,
people had no way of determining when to sow or
harvest except by looking at these patterns in the
sky. Ancient people developed a way to remember
the patterns by giving these patterns names and
stories. For example, in the northern hemisphere,
the constellation Orion indicates the coming of
cold season. The constellations made it easier for
them to recognize and interpret patterns in the
sky.

39.  For example, Gemini is seen in the
Philippines during the months of April and
May. Farmers interpreted the appearance of
Gemini as the end of planting season and it
signified rich harvest. The table below
shows how the Matigsalug Manobo of
Bukidnon used the stars and constellations
in relation to their agriculture.

40. Local Name
Month of
Appearance
Related
Agricultural Act.
Western
Equivalent
Baha Dec to Feb Clearing of forest Taurus
Pandarawa January Start of planning
what crops to be
planted & how wide
is the area
Pleiades
Balatik Feruary Start planting &
setting of traps
Orion’s Belt
Malihe March Planting of
rice,corn & veggies
Gibbang April & May End of planting
season, signifies
rich harvest
Gemini
Malara May Stop planting Canis Minor

41. Lepu Late May Time to clean or
clear the fields
while waiting for
harvest time
Aquila
Buwaya June Start of the rainy
season

42. Other Uses
 Another use of constellations was in
navigation. The Polaris is widely used in
navigation because it does not change its
position at any time of the night or year.
Also, one can figure out his/her latitude just
by looking at how high Polaris appears in
the night sky. This allowed sailors to find
their way as they sail across the seas.

43. Group Activity
 In groups of five, observe the sun by capturing its
image on a cardboard. Obtain a telescope and a
square of white cardboard. Let one member hold
the cardboard while another member holds the
telescope in a reversed viewing position in order to
capture the image of the sun onto the cardboard.
DO NOT LOOK DIRECTLY AT THE SUN! Adjust
the board and the telescope so that the image of
the sun falls on the board. Focus the telescope
until the sun’s image becomes sharp. Try to
identify sunspots and prominences.