The Cosmic Explorer
(600-2409) Operation Faxback Doc. # 33044
HOW TO SET UP THE COSMIC EXPLORER FOR ANY GIVEN DATE:
As you know, the 3-D Star Map on the Cosmic Explorer shows you the nearby
stars visible from our region of the Orion spiral arm of the Home Galaxy.
The Star Seeker represents you, somewhere on Earth. The stars, galaxies,
star clusters, and nebula we see from Earth seem to stay in place for
years. Planets, however, are constantly moving so you will have to refer
to the planet charts to find where they are in the sky.
Let's say you want to see what stars are up on the night of July 10. Let's
also say you live at about 25 degrees N.
1. Pick up the Star Ball and look at the Sky Calendar as you rotate the
ball to the left. As you do this, the months of the year progress
normally. Find July 10.
2. Set the Star Ball on the Power Base so that July 10 is just above the
West horizon. Keep the equator aligned with the two arrows on the
E and W cardinal points. You will see the words "EQUATOR HERE"
printed on the horizon Ring.
3. Now you are set up for sunset on July 10. Notice how far North the
sun sets at that time of year! The Sky is still too bright to see any
stars. You will have to wait about 2 hours before the sky is dark
enough to observe. By then, the Sky will rotate westward by 30 degrees.
To adjust your Star Ball for 2 hours after sunset, turn the ball to the
left so that the hour increments on the EQUATOR move from 8^h to 10^h.
The Sky rotates at 15 degrees/hr.
4. Look at the Star Ball and you will see that Corona Borealis and
Hercules are near the zenith. Leo is setting the West, while the three
constellations whose brightest starts make up the super star pattern
called the summer Triangle: are high in NE part of the sky. These
constellations are Lyra, Cygnus and Aquila.
5. To keep track with the constantly rotating sky, use the hour markers
on the Equator as references. The time of sunset depends on your
attitude. For the observer at 25 degrees N latitude, as shown in
Figure 8 and 9, sunset comes early at about 6:50 p.m. (1850). For an
observer at 54 degrees N, sunset comes at about 8:30 p.m. (2030). In
any case, note the time of sunset and look at the Star Ball to see
which hour of RA is on the western horizon. For July 10, we saw that
the 8^h is on the western horizon. To keep track of the turning sky,
simply advance the Star Ball westward for every hour change on your
clock. Remember, RA hours are broken into 60^m increments if you want
to make smaller adjustments.
As you can see, this is a very simple process. The more you use it, the
easier the process becomes and your understanding and knowledge of the
sky, its inhabitants and its motions, will increase greatly.
PLOTTING PLANETARY POSITIONS
The visible planets - (Mercury; Venus; Mars; Jupiter; and Saturn) - can be
seen to move compared to the stars, which seem fixed in space. That is
why we cannot print the planet positions on the Star Ball. Here is how to
use the information in the Planet Position Table to locate the planets up
to the year 2001. Let's stay with July 10 and let's pick 19993 as the
year for our observation.
The Planet Position Table shows the following information for July 1, 1993.
(The planets will not change position much between July 1 to July 10 except
for Mercury and Venus.)
July 1, 1993: 8/7.9^h, -18 degrees (Mercury) 4/3.6^h, + 16 degrees (Venus)
11/10.5^h,+11 degrees (Mars) 12/12.4^h, - 1 degree (Jupiter) 22/22.2^h, -13
degrees (Saturn)
Look at the coordinates for Mercury:
Rounded off RA: 8 (8/7.9^h, -18 degrees) More precise RA: 7.9^h
Declination: 18 degrees, South of equator (- means South, + means North)
If you are not a telescope owner and just want to find the planets in the
sky, use the rounded off RA value, 8^h in this case.
Pick up the Star Ball and find 8l^hk on the equator; it is just to the
right of Canis Minor. Mercury is on that hour circle, but where? Simple,
the planets are always found near the Ecliptic on which the Sky Calendar
is printed. So, if you look northward from the 8^h to the Ecliptic you
will see that the planet Mercury would be between Gemini and Cancer on
July 1, 1993. Where will you find Venus, Mars, Jupiter, and Saturn on the
same night?
Venus, at 4^h, is in Taurus and will be visible before dawn
Mars, at 11^h, is in Leo, low in the west at first dark
Jupiter, at 12^h, is Virgo, high in the west at first dark
Saturn, at 22^h, is in Aquarius, very low in the east at first dark,
but it will be in the sky all night! You need 30x in order to see its
ring system.
You may have to interpolate a bit for the faster moving planets (Mercury
and Venus), but that is simple to do. Once again, with a little practice
and patience you will become an expert planet plotter.
OBSERVING OUTSIDE WITH THE COSMIC EXPLORER:
Let's say you take the Cosmic Explorer outside on July 10. Set it up so
that the W on the horizon Ring is pointed west (about 23 degrees south of
the sunset point on July 10). Now, the other cardinal points will be
correctly oriented; N with North, E with East, and so on. As the Sky
darkens, rotate the Star Ball westward, as we described previously, to
compensate for the Earth's rotation. Watch carefully for emerging bright
stars and planets as the sky darkens. Soon, you will be able to trace out
the dimmer stars and the constellations will become recognizable.
Red Filter Use:
Put the Red Filter over the light lens so that it is completely covered
with the red light shining into the Star Ball. You will have enough light
to see the constellation names, stars, and other printed information
without degrading your night vision. You will have enough light to see
the constellation names, stars, and other printed information without
degrading your nights vision. You will see far more stars after about
20 minutes sitting under the darkening sky than when you walk from a
brightly lit home into a dark night. Relax and enjoy the pleasures of
cosmic exploration.
Phosphorescent Stars:
About 170 of the more than 850 stars printed on your Star Ball have been
hand painted with a safe but bright phosphorescent acrylic paint. Use the
white power light for a few seconds to excite the "phosphostars". With
the lights out, indoors or out you can enjoy your personal glow-in-the-dark
cosmos.
BASIC ASTRONOMICAL DATA:
Much is known about heavenly objects near us. By near, we mean out to
about 1,000 Light Years. Each Light Year equals about 6 trillion
(6 x 10^12) miles or about 63,240 Astronomical Units. Each Astronomical
Unit is about 149,600,000 km or 93,000,000 miles. One final unit should
be mentioned. It is very commonly used by astronomers and you may see it
as you read more about the subject. It is called a parsec (pc) and it
equals 3.26 Light Years. There are KPC (1,000 pc) and MPC (1,000,000 pc)
and MPC (1,000,000 pc) units also.
Miles and Astronomical Units are used for distances within the Solar
System. Light Years and parsecs are used for distances out to 1,000 Light
Years or about 300 pc.
For distances to other galaxies, you will see KPC's or LY's used.
EXPLANATION OF TERMS USED IN STAR TABLES
Names:
The visible NEAREST stars have common Greek and Arabic names, as do all of
the 20 BRIGHTEST stars. Those stars with an apparent brightness number
greater than 5 are not bright enough to have been given names. Those
stars with names or letters followed by numbers are named for their
discoverers (i.e. Barnard's*) or for the special star catalog they are
found in (BD + 43 degrees 44).
RA and DEC:
As discussed previously, these coordinates are used to locate objects in
the sky. The following section describes how to use the Degree Scale with
the Star Ball to find the position of RA and DEC coordinates on the Star
Ball.
D: This is the Distance of the star from our solar system in light years.
Spectral Type:
The stars are very hot masses of luminous gas, mostly Hydrogen and Helium
with a sprinkling of other elements. By examining their light after
passing it through a prism or diffraction grating, astronomers can
determine the color and energy balance of the spectrum, plus the pattern
of absorption bands in the spectra. They then arrange the stars on a
temperature scale, as indicated by their spectra. The scheme, once
alphabetical, has been reorganized to look like this:
O B A F G K M
Hottest................Coolest
Bluest.................Reddest
Youngest...............Oldest
Luminosity Class:
The Luminosity Class of stars is generally used as a descriptor to
Spectral Class. The reason is that there are many kinds of stars of very
similar Spectral Type. For example, consider Star #19 or the Brightest
Stars (Betelgeuse) and Star #20 or the Nearest Stars (CD-36 degrees 1593).
They are both M2 spectral types, but look at their respective Mv's.
Betelgeuse is a -5.6 and the other is a +9.6. The difference in magnitude
is about 15. Each increment of magnitude equals a change of 2.512 times
itself 15 times, or (2.512)^15. That is about a 1,000,000 times
difference in luminosity or power output. Since both stars are the same
temperature, the difference in power output must be due to -SIZE!
Betelgeuse must be gigantic compared to the red, dwarfish CD-36 degrees
1593. And it is!
The Luminosity Class Scheme is shown below:
Ia: Most Luminous Supergiants
Ib: Less Luminous Supergiants
II: Bright Giants
III: Normal Giants
IV: Subgiants
V: Main Sequence Stars, including Dwarfs, but not white Dwarfs (D)
Radial Velocity:
This is the velocity at which the star and our sun are approaching or
receding relative to each other. A+ sign indicates the star is moving
away from us, relatively speaking; a - sign indicates an approaching star.
Apparent Brightness:(V)
This stands for visual magnitude, or how bright the stars appear to be at
their different distances from Earth. The higher the V of a star, the less
bright it is. That means that a star with a V of 8 is less bright than a
star with a V of 5. The V scale was established more than 100 years ago.
Its zero point equals the brightness of the next brightest stars after the
Sun, Sirius, Canopus, and Arcturus. Some stars have negative visual
magnitudes. That is because they are brighter than most visible at night.
The brightest sky objects, because they are so close, are the Sun and
Moon, followed by the nearer planets. If a small letter v follows the
value of the star's brightness, that means the star varies in brightness.
Factors that affect the apparent magnitude (or brightness) of a given star
are its power output (luminosity); the transparency of space through which
its light travels; and its color. Though space is usually thought of as
empty, it is actually a dusty and gaseous region, especially in our part
of the galaxy.
Absolute Magnitude (Mv):
This is the star's absolute visual magnitude. Astronomers need to compare
stars to each other in terms of a standardized unit of distance. This
distance is selected as equal to 10 parallax seconds of arc or 10 parsecs
10 pc, for short. At that standardized distance, the difference in a
star's brightness or magnitude would be due primarily to its power output,
or luminosity. Like apparent magnitude, the smaller the magnitude number,
the brighter the star.
Look at the MY column in Tables 3 and 4. You may be surprised to see that
some of the stars that look the brightest (with the smallest Mv) are not
very powerful sources of energy compared to less bright stars that are
very much further away.
USING THE DEGREE SCALE AND RA ON EQUATOR TO LOCATE POSITIONS ON THE
COSMIC EXPLORER:
There are 41,253 square degrees on the Star Ball. We have printed about
868 stars plus several non-stellar objects. You can quickly locate a star
or object by using the RA and DEC coordinates.
Let's say you want to find the star Procyon, which is listed on the 20
nearest and the 20 brightest stars. Its coordinates are: 07h 39^m +5
degree.
Start by picking up the Star Ball and looking along the Equator to find
the 7^h. See it, just east of Orion. Next, estimate where the 39m mark
would be between 7^h and 8^h. You can figure it is about 2/3 of the way
to the 8^h increment. Now align the -0 degree mark on the degree scale
with the center of the Equator. Do this so that the right edge of the
Degree Scale is at the 7^h 39^m point. Next, look at the 5 degrees mark
on the Degree Scale. It should be right on, or very close to, the star
Procyon. Remember, most of the brightest stars are phosphopainted-another
helpful clue.
Try this method for several other stars and non-stellar objects. You will
soon find it a very simple and quick procedure. You can also use this
method to find any comets, novas, or supernovas which may appear from time
to time in news reports. The coordinates are often given too. Now you
have a way to locate them on the Cosmic Explorer and then in the night
sky. Knowledge is Power!
Table 2
Bright non-stellar objects visible from earth that are printed on the star
ball: (See Faxback Doc. # 33320 for Tables 2 through 6)
(BR/EB 5/10/96)
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