Download May - RASC St. John`s Centre

ADDING CONSTELLATIONS AND THEIR MYTHOLOGY
TO YOUR STAR-GAZING PLEASURE
Familiar to everyone, the Big Dipper is the most prominent
asterism (distinctive grouping of several stars) in the northern
sky, and it can be used as a convenient guide to several
constellations that surround it.
Four stars form its bowl and
three its curved handle. The
two stars that form the front
edge of the “dipper” point
towards Polaris, the North
Star, about 28º away – this
provides a check of distance
approximation. The Big Dipper’s
orientation in the sky changes
during the night and through the
year, but it is circumpolar and its
position relative to nearby
constellations remains the same as it
revolves around Polaris, which is very
near the Celestial North Pole and
remains in a fixed position.
The Big Dipper is part of the
constellation Ursa Major, the Great Bear.
Its other stars which make up the bear’s
head and legs are much fainter but still
quite visible to the unaided eye on a
clear, dark night. Polaris is the brightest
(alpha) star in Ursa Minor, the Little
Bear. It marks the end of the handle of
what is commonly called the Little
Dipper, which curves around to face
the upper part of the Big Dipper.
The story of the two bears involves
Zeus, king of the Olympian gods. He
loved a nymph named Callisto who
lived in the mountains and liked to hunt.
The goddess Hera, Zeus’s wife, was jealous
of Callisto and turned her into a bear, although
inside she remained a person. One day her son Arcas was out
hunting and spotted a bear. Not knowing it was his mother, he
was about to kill the bear with his spear. Zeus, however, was
looking down from Mount Olympus and saved Callisto by
turning Arcas into a bear as well. He then grabbed both by their
tails and lifted them into the heavens, stretching their tails in the
process. This is why Ursa Major (Callisto) and Ursa Minor
(Arcas) have much longer tails than normal bears.
Tracing the arc of the Big Dipper’s handle for about 30º will
find Arcturus the alpha star in Boötes, The Herdsman. Arcturus is
one of the very bright stars in our sky but others in this
constellation are faint. The story has Dionysus, the god of wine,
visiting Icarius, a mortal, and being so pleased with his host that
he thanked him by teaching him how to grow grapes and make
wine. Icarius traveled the country to teach others, bringing wine
for them to taste. He met some shepherds and gave them some
wine cautioning them to mix it with water before drinking. This
they failed to do and got so sick they thought Icarius had tried to
If it is above our southern horizon, extending the arc onward
from Arcturus another 30º will locate Spica in Virgo, The Virgin.
This constellation honors Persephone, the beautiful daughter of
Zeus and his sister Demeter, who was abducted by Hades, brother
of Zeus and god of the Underworld, who wanted her as his wife.
Virgo is one of the 12 zodiac constellations which encircle the
sky along the ecliptic, the Sun’s apparent path through the stars
marking the Earth-Sun orbital plane.
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The two stars forming the back edge of the Big Dipper
adjacent to the handle point upward in the sky towards two other
very bright stars about 60º away. One is Vega in Lyra, The Lyre,
which Appolo, the god of music as well as the Sun, gave his son
Orpheus with which he played the most enchanting
music. Arcing slightly in the direction of Polaris
along this line finds Deneb in Cygnus, The
Swan, also known as the Northern Cross.
These two form the base of the Summer
Triangle, the third is Altair another
bright star 30º away in Aquila, The
Eagle. In the opposite direction these
same two stars of the dipper’s back
edge point to Regulus 40º away in
Leo, The Lion, another of the
zodiac constellations.
May - Mid June
Shawn Martin, RASC, St. John’s Centre
PLANETS
Venus (magnitude –3.9) the bright Evening Star shining in
the west-northwest during and after twilight.
Mars (magnitude +0.5) high in the west during evening in
the constellation Cancer.
Jupiter (magnitude –2.2) is low in the dawn. Look for it
above the eastern horizon.
Saturn (magnitude +0.7) is high in the southwest during
evening, in the constellation Virgo.
Uranus (magnitude 5.9) is in the background of Jupiter at
dawn, in the constellation of Pisces.
Neptune (magnitude 7.9) is viewable just before dawn well
to Jupiter's upper right. On the Aquarius-Capricornus
border.
The diagonal line from
the star where the handle
joins the bowl of the Big
Dipper to the bottom star
of the front edge points to
Gemini, The Twins
(Castor and Pollux),
another of the zodiac
constellations 45º away.
The two stars forming
the top edge of the bowl
point away from the
handle to Capella, another
of the sky’s very bright stars, in
Auriga, The Charioteer, some 50º
away.
WARNING! When using a telescope or binoculars, always be sure NEVER TO LOOK
AT THE SUN! This can cause serious and permanent eye damage. To be safe, always make
sure the Sun is fully set below the horizon before going outside with your telescope or
binoculars.
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In the same way, the first star in
the handle of the Big Dipper
aligned with Polaris points to
Cassiopeia, The Queen, 25º beyond. The
three middle stars of this W-shaped constellation
can be used to find two other well-known
constellations. The central star and the star forming
the bottom of the W in the direction of Capella point
to Perseus, The Hero, 15º away. The central and the
other of the W’s bottom stars point to the Great
Square of Pegasus, The Winged Horse, 35º away.
All of the very bright stars mentioned above,
along with many of the other brighter ones in each
constellation, are more obvious and easier to locate
during twilight, before all the fainter stars
surrounding them become visible as well. These
won’t all be above the horizon at any one time, but
once you’ve learned to find a few of them,
constellation charts make it easy to find many others.
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It will be useful first to become
familiar with a simple way to
approximate “apparent” distance between
the stars. This is expressed in degrees
representing an arc of the great celestial sphere
overhead. At arm’s length and with fingers spread fully, the tips
of the thumb and little finger span about 25º across the sky
beyond. Similarly, the tips of the little and index fingers span 15º,
the knuckles of the fist 10o, the tips of the three middle fingers
5º, and the tip of the little finger 1o.
poison them. The shepherds chased after Icarius and killed him.
When Dionysus found out he punished the shepherds by placing
a plague upon their land. Icarius was raised to the sky and
honored as the constellation Boötes.
The constellations that can be found so readily using
the Big Dipper as a guide, and being able to recognize
even just a few of the constellations and knowing some of
their stories make the night sky all the more fascinating. In a
way it allows us to connect with ancient ancestors whose lives
were so powerfully affected by what they saw in the sky.
Jerry Ennis RASC, St. John’s Centre
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Point this month’s star
chart toward North and
match the stars with
those in the real sky.
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On a clear, dark night, for anyone
who takes the time to gaze for just a
short while even, the stars overhead
provide a magnificent light show. This
article is intended as a starting point.
ACTIVITIES
1. Look in the newspaper for names of objects that have the
same names as objects in the sky.
2. Check the weather map in The Telegram for a night when it
would be good to search the night skies.
3. Are there any articles in The Telegram that make any
reference to what we may find in the night sky.
You can contact the Royal Astronomical Society of Canada,
St. John’s Centre, at www.rasc.ca/stjohns/
Newspaper In Education
THE TELEGRAM