"The Little Bear"
Mythology: One
story of Ursa Minor links the Little Bear to Ursa Major, the Great Bear,
and to Bootes, the Herdsman. This story
begins with Zeus' infatuation with a beautiful young woman named Callisto
(after which a moon of Jupiter is named), the daughter of King Lycaon of
Arcadia. Callisto was a great hunter and was often in the forest.
As a result, she was a follower of Artemis, Goddess of the Hunt.
As part of her sworn loyalty to Artemis, Callisto took an oath of celibacy.
One day, Zeus learned of the beautiful Callisto and disguised himself as
Artemis to approach her. Upon revealing himself to her, Callisto
struggled against him, but to no avail. Artemis banished Callisto
from the forest and Callisto became pregnant with Zeus' child -- Arcas.
Hera (Zeus' wife) was never pleased
with Zeus' infidelities, and often took her jealousy out on Zeus' "conquests."
Because of this, Hera turned Callisto into a bear.
Later, King Lycaon invited Zeus
to dinner. To test Zeus, Lycaon had Arcas cut up and served as a
meal to the Olympian God. When he realized what had happened, Zeus
killed the sons of Lycaon with his thunderbolts and then turned Lycaon
into a wolf. Zeus gathered the pieces of Arcas and reassembled them.
Arcas was given to the Pleaide Maia to be raised. Later, when Arcas
had grown, he was out hunting and stumbled across the bear that was his
mother, Callisto. The bear ran to the temple of Zeus, with Arcas
following her in an attempt to slay the bear. Upon reaching the temple,
Zeus brought both of them to the sky -- Callisto became Ursa Major, the
Great Bear, and Arcas became the Bear Herder, Bootes. However, in
some versions of the story, Arcas became the Little Bear, circling around
in the night sky with his mother.
The above offers one possible story
for Ursa Minor, and I mentioned it first because it involves other familiar
characters (constellations) with just a slight twist on the ending.
There is another story that involves Ursa Minor, and it is not trivial
(unlike the other constellation descriptions, where I have placed the stories
in order of significance). The following is also a popular story
involving Ursa Minor, and is important because it involves the birth of
Zeus, the leader of the Olympian Gods:
Zeus and the Olympian Gods were
not the first generation Gods on Olympus; they are actually the third.
Zeus himself was the seventh child of the Titan Ruler Cronus (Roman name:
Saturn) and Rhea (Roman: Ops, Cybele). According to prophecy, one
of his children would overthrow him and be the new leader of the Gods.
Cronus dealt with this problem in a rather unusual way -- he ate his children!
Rhea was able to save Zeus by tricking Cronus into eating rocks instead
of the infant Zeus. Zeus was taken to the island of Crete, where
Adrasteia and Ida (two nymphs) raised Zeus in a cave. To further
prevent Cronus from knowing that Zeus was still alive, Cretan Warriors,
called Curetes, stayed outside the cave making a lot of noise to cover
the crying of Zeus.
The prophecy did come true:
Zeus and the Olympian Gods battled for ten years against Cronus for control
of Olympus. Zeus did overthrow Cronus and (it gets worse) forced
Cronus to regurgitate his siblings! These siblings became the Olympian
Gods that we are familiar with. After the war, Zeus and the Olympian
Gods controlled the Universe.
What does all this have to do with
Ursa Minor? The Little Bear is associated with either Ida or Adrasteia,
in honor of them taking care of the infant Zeus. No story explains
how they might have been turned into a bear, nor specifically which nymph
Ursa Minor is.
Other Interesting Sights:
The star Polaris, the first in the tail of Ursa Minor, is unique among
the stars in the night sky -- it is the only one that doesn't seem to move!
That is because it is located on top of the Celestial Sphere, very close
to the North Celestial Pole (where Earth's North Pole and axis of rotation
points.) As a result of its location, as Earth rotates, Polaris appears
to remain in the same location (in actuality, it is off the North Celestial
Pole by about one degree, but our eyes can't discern the difference).
Therefore, Polaris seems to be the center upon which all the other stars
and constellations move around.
The name Polaris is derived from
the Latin Stella Polaris, meaning "Pole Star." Since Polaris
is located almost directly over the North Pole, it serves as an indicator
for the direction North. This was very important to early explorers
and sailors, for it provided them with a fundamental Cardinal Point long
before the compass was invented.
Polaris is the proper name for
this star, but it is often simply called the "North Star." But "North
Star" is more like a title than a name. Consider, for example, the
title "President of the United States;" different people with different
names may occupy that title. Such is the same with the North Star.
As early as 320 BC, the ancient Greeks knew that Polaris did not exactly
mark the North Celestial Pole, but it is actually getting closer and closer:
As Earth spins on its axis, it wobbles, much like a spinning top will carve
out a cone. This phenomenon is called precession. Earth's precession
is 25,000 years; that is, its axis of rotation will carve out a complete
circle every 25,000 years (therefore, the North Celestial Pole is also
constantly moving, and star charts and tables must constantly be adjusted
accordingly). Polaris will actually be nearest the North Celestial
Pole between the years 2105 and 2127.
It must follow that there are other
stars that can be the North Star, and that there are times when no (visible)
star lies at the North Celestial Pole to be the North Star. Before
Polaris, the star Thuban, in Draco (third to the last star in the Dragon's
tail) was the North Star (around 3000 BC). In about 5,000 years,
Alderamin, in Cepheus, will have that role. Then, 7,000 years from
now, Deneb, the bright star in Cygnus, will act as the Pole star, followed
by Vega, in Lyra, 12,000 years from now. It should be stressed that
these stars come close to being a "true North Star," but never lie directly
on Earth's precession circle.
Polaris can be found by lining
up the last two stars in the cup of the Big Dipper, Dubhe and Merak.
These two stars are called "pointer stars" because a line drawn between
them and extended into space will point out Polaris, and Ursa Minor.
Just like with Ursa Major, which
contains the asterism the Big Dipper, Ursa Minor has within it the asterism
of the Little Dipper. In fact, Polaris also acts as the end of the
handle of the Little Dipper.