constellation

2.  Stars undergo nuclear reactions
that burn hydrogen in their cores;
planets do not. Stars are more
massive compared to majority of
the planets. Stars are formed when
a gas cloud out in the nebula or
other region of interstellar space
collapses under the influence of
gravity. On the other hand, the
planets are created when materials
in the disk around a pre existing
stars begins to condense around
rock or cycle core.

4. The brightness of a star is
described of MAGNITUDE
and LUMINOSITY.
The MAGNITUDE of a star is
based on a more than 2,000
year old scale which was
devised by Greek astronomer
Hipparchus in 125 BC.
Hipparchus assigned starts
to six groups of brightness
called MAGNITUDES.

5. APPARENT
MAGNITUDE –
The brightness of a
star viewed from
the earth.
ABSOLUTE
MAGNITUDE –
The actual
brightness of a
star.

6. LUMINOSITY – is the
power of a star. It is the
rate at which the star (or
other bright objects)
radiates light energy.
Luminosity depends on
size and temperature; it is
proportional to the surface
area of a star ad the fourth
power of its surface
temperature.

7. In order to calculate how far a
star is, astronomers use the
parallax method. PARALLAX
is the measurement of the
shift of a nearby object
compared to distant objects
when observed from two
different positions. Because of
the earth’s revolution around
the sun, near stars seem to
shift their positions against
the farther stars and this is
called PARALLAX SHIFT.

8. Stars generally appear white in
the sky, but if you will look
carefully, you will notice a range
of colors varying from white,
blue, red, yellow, or eve gold. For
instance, the constellations of
Orion the Hunter displays a
beautiful contrast as the red
Betelgeuse at Orion’s armpit and
the blue Rigel at the leg of Orion
can be observed in the sky.

9. About 90% of all stars are
main sequence stars. Among
these main sequence stars,
the hottest stars generate the
most light and the coolest
generate the least. Our sun is
classified as a main sequence
white dwarf star and it is at
the central part of its
evolution. Main sequence
starts exhibit the fusion of

10. Stars with a mass of about 0.8
to 10 times the solar mass of our
sun are called GIANT STARS.
GIANTS STARS are those with
a mass of more than 10 times
higher than that of our sun and
a luminosity nearly 1,000,000
times as great. Super giants are
tenuous tars and their lifetimes
are probably only a few million
years extremely short on the
scale of stellar evolution.

11. COLOR SURFACE
TEMPERATURE (K)
NAME OF STAR
Red 1,500-3,500 Betelgeuse, Antares
Orange 5,000 Arcturus
Yellow 6,000 Sun, Canopus
White 7,500-11,000 Vega
Bluish-white Over 25,000 Rigel

14.  Look at the image and observe some shapes and figures formed by a group of
stars. You will notice that groups form patterns or figures. These patterns of
starts which are seen in the sky are called CONSTELLATIONS.

15.  As defined by the International
Astronomical Union (IAU) in the early
twentieth century, constellation is an
area of the celestial sphere composed of
stars that appear to be located close
together in the sky. They form
imaginary outlines or patterns that
typically represent inanimate objects,
animals, and mythological creatures.
 The IAU divides the sky into 88
constellations with exact boundaries, so
that every place in the sky belongs
within a constellation. Of these, 48
were already recognized in ancient
times and had been listed by the
astronomer PTOLEMY.
 These 48 constellations were named
based on Greek and Roman Mythology.

16. The star patterns that have been
discovered but have not been
officially identified as
constellation are called
ASTERISM. The most famous
example of asterism is the BIG
DIPPER, a constellation that is
quite common as it was even
featured on the Alaskan state
flag. The reason why it is not
considered a true constellation is
because it is a part of a larger
constellation, called URSA
MAJOR (THE GREAT BEAR).

17. Constellations are groups of bright stars which appear close to
each other on the sky but are actually light years apart in space.
The shapes of the constellations depend on the point view of the
person looking at them from the earth.
Astronomers officially recognize 88 constellations distributed in
the entire space. They can be viewed from the North and South
Hemispheres of the earth. Currently, 14 men and women, nine
birds, two insects, 19 land animals, 10 water creatures, two
centaurs, one head of hair, a serpent, a dragon, a flying horse, a
river, and 29 inanimate objects were named and located in the
night sky.

18. The 88 constellations are divided into two groups
relative to their position from Earth. There are 44
constellations visible in the sky north of the equator and
the remaining 44 constellations can be viewed in the
southern sky. People living in the Northern Hemisphere
see only the constellations in the northern sky. The
people living in the Southern Hemisphere see only the
constellations in the Southern Sky.

19.  The Big Dipper is part of the constellation
Ursa Major. Notice how the front two stars
of the Big Dipper point directly at the star
Polaris. POLARIS, also known as the North
Star, is located at the end of the Little
Dipper; part of the Ursa Minor. Polaris is
almost directly over the Earth’s north pole.
As the earth rotates, you can watch Ursa
Major, Ursa Minor, and other constellations
in the northern sky circle around Polaris.
Because this constellations circle Polaris,
they are called CIRCUMPOLAR
CONSTELLATIONS.
 CIRCUMPOLAR CONSTELLATIONS – are
constellations that move in a
counterclockwise direction. At any given
night, these constellations are visible during
the portion of the circle, while the rest is
traced out when the constellations are

20. ORION – It is the one of the most
prominent stars patterns in the
sky. It is known as
“THE HUNTER” located on the
celestial equator and visible
throughout the world. Its family
includes five constellations;
ORION (The Hunter), CANIS
MAJOR and CANIS MINOR
(Orion’ two Gods), MONOCERES
(The Unicorn), and LEPUS (THE
HARE).

21. URSA MAJOR – it is also
known as “BIG BEAR” and is
one of the most famous
constellations. It can be seen all
year to those who are at the
Northern latitude of the earth.
Its family includes 10
constellations circling the
northern celestial pole; URSA
MAJOR (containing Big
Dipper), URSA MINOR
(containing Polaris, the
northern star), CANES
VENATICI, BOOTES, COMA
BERENICE, CORONA
BOREALIS,

22. CASSIOPEIA – according
to Ian Ridpath’s star
tales, cassiopeia was a
vain and boastful wife of
King Cepheus of Ethiopia
who lives next to her in
the sky they are the only
husband-and-wife couple
among the constellations.
It appears to be one of the
brightest in the Northern
Hemisphere.

23. DRACO – one myth
claims that DRACO is
always visible in the
Northern Hemisphere
but not in the
Southern Hemisphere.
The name Draco “THE
DRAGON” is derived
from the Latin term
DRACONEM meaning
huge serpent.

24. HERCULES – it is a
constellation named after the
Greek hero Herakles, who was
the greatest of the Greek
heroes and was famous for his
12 labors. This constellation
belongs to one of the 48
originals plotted by Ptolemy
and has survived time to
become one of the 88 modern
constellations adopted by the
International Astronimical
Union (IAU).

27. You do not see all the
constellations in one night. Some
of the constellations can be seen
only during certain seasons. The
part of the sky visible at night at
a particular place gradually
changes as the season changes,
also, you should know that in any
one evening, the observers at
different latitudes see different
constellations.

28. Astronomers divided the constellations into three
regions;
1. NORTH CIRCUMPOLAR CONSTELLATIONS – they
are seen by the observer at the Northern Mid-Latitude.
2. SOUTH CIRCUMPOLAR CONSTELLATIONS – they
are seen by the observer at the Southern Mid-Latitude.
3. EQUATORIAL CONSTELLATIONS- they lie on either
of the celestial equator which is the projection of the
earth’s equator to the sky.

29. Every three months, the earth
travels about one-fourth of its
orbit. This, for each season, the
earth is exposed to different
constellations. A different zodiac
constellation also appears every
month. The word ZODIAC means
“CIRCLE OF ANIMALS” in
Greek. There are 13 equatorial
patterns in astronomy. They have
been used as astrological signs
which have 12 signs that actually
match the celestial constellations.

30. The constellations that astronomers
used to identify parts of the sky are
not the same as the zodiac signs used
by astrologers. For example,
OPHIUCHUS is recognized in
astronomy but not as astrological sign.
The zodiac signs were based on the
constellations 2,000 years ago when
their modern (LATIN) names were
first used. The signs are an
astrological convenience, ignoring the
differences between two different types
of solar calendar.
The difference in the two solar
calendars is caused by an astronomical
phenomenon called PRECESSION.

31. STAR SIGNS (TRADITIONAL AND ACTUAL)
CONSTELLATION TRADITIONAL ACTUAL (2011) DAYS
Capricornus Dec.22-Jan.21 Jan.20-Feb.16 28
Aquarius Jan.22-Feb.21 Feb.17-Mar.12 24
Pisces Feb.22-Mar.21 Mar.13-Apr.19 38
Aries Mar.22-Apr.21 Apr.20-May 14 25
Taurus Apr.22-May 21 May 15-June 21 38
Gemini May 22-June 21 June 22-July 21 30
Cancer June 22-July 21 July 22-Aug.11 21
Leo July 22- Aug.21 Aug.12-Sep.17 37
Virgo Aug.22-Sep. 21 Sep.18-Oct.31 44
Libra Sep.22-Oct.21 Nov.1-Nov.22 22
Scorpius Oct.22-Nov.21 Nov.23-Nov.30 8
Ophiuchus Dec.1-Dec.18 18
Sagittarius Nov.22-Dec.21 Dec.19-Jan.20 33