Download Constellations and Light Pollution

Lab “3”: Constellations and Light Pollution (Lab 8)
Name: _________________________________
Lab Partner(s): _________________________________
Section: _________________________________
WHAT IS LIGHT POLLUTION?
Theft of the Night
Text of a December 1989 National Academy of Sciences Press Release by David L. Crawford
Most Americans are growing up unable to see the stars their grandparents knew so well. They
see the night sky only in pictures or at planetariums. This is true not only in cities, but also in
many suburbs where street lamps and other sources of "light pollution" have obscured our view
of constellations, meteor showers, and planets.
Indeed, many youngsters may now say, after viewing the night sky in a rural area for the first
time, that "it looks just like the planetarium".
Light pollution is not a matter of life and death. Yet it is important nonetheless, profoundly so.
We human beings lose something of ourselves when we can no longer look up and see our place
in the universe. It is like never again hearing the laughter of children; we give up part of what we
are.
Such a loss might be acceptable if light pollution were the inevitable price of progress, but it's
not. Most sky glow, as scientists call it, is unnecessary. The light that obscures our view of the
night sky comes mainly from inefficient lighting sources that do little to increase nighttime
safety, utility, or security. It produces only glare and clutter, costing more than $1 billion
annually in wasted energy in the United States alone.
For science, the impact has been even more tangible and adverse. Astronomers require
observations of extremely faint objects that can be made only with large telescopes at sites free
of air pollution and urban sky glow. For example, scientists interested in how the universe was
formed may study the light of galaxies and quasars at incredibly vast distances from Earth. These
images offer information about faraway corners of the universe, helping us understand how our
own world was formed. Yet, after traveling countless light years, the light from these objects can
be lost at the end of its journey in the glare of our own sky.
Space-based telescopes, such as the Hubble Space Telescope, offer one way around the problem.
However, large telescopes on Earth will always be used, if only because they are accessible, cost
much less than orbiting devices, and can do many jobs more cheaply.
In fact, our experience over the past two decades has shown that space-based astronomy, far
from reducing the need for ground-based observations, actually increases the demand for these
facilities. New telescopes now planned or under construction on Earth will complement the
knowledge we gain from telescopes in space, but only if they are not compromised by
encroaching light pollution, as has occurred at Mount Wilson, near Los Angeles, and several
other older observatories.
Reducing light pollution is not difficult, but it does require that public officials and ordinary
citizens be aware of the problem and act to counter it. Low-pressure sodium lights, for example,
can replace existing fixtures for most streets, parking lots, and other locations. They reduce glare
and save money.
Another fairly painless way to reduce light pollution is with outdoor lighting control ordinances,
over 50 of which have been enacted throughout Arizona and in several key cities and counties in
California and Hawaii. These measures typically require communities to prohibit inefficient,
low-quality lighting. Not only do they help preserve dark skies, but they also enhance energy
efficiency. An outdoor light system recently installed at a prison in Arizona, for example,
improved security and reduced light pollution while cutting energy costs by 50 percent. There is
no reason that all communities should not have such efficient lighting.
On an individual level, people can help reduce sky glow by using night lighting only when
necessary, choosing well shielded fixtures and turning off lights when they are not needed.
Curing light pollution saves money while reducing glare. Unlike other issues involving pollution,
it presents us with a rare case where we should strive to be kept in the dark. The stars above us
are a priceless heritage, not only for scientific knowledge, but also for our identity as human
beings.
More of our children, and their children, should be able to look up at night and see that the Milky
Way isn't only a candy bar.
LAB INSTRUCTIONS:
In this lab, you will observe 6 constellations and one open cluster and record your observations
in the log included. Then you will answer several questions. On a scale of one to four, one being
the most easily visible, six of the eight constellations listed are rated “1” and two are rated “2.”
This indicates that the given constellations have a number of relatively bright stars.
In your sketch of each constellation, indicate the brightness of each star by using different sized
dots. If you can tell that a star is a certain color, please note it beside the star. If a star is named
on your planisphere, then please label it in your sketch. Only draw the stars that you see.
Required Constellations:
Canis Major: The great dog loyally follows its mythical master, Orion, across the southern skies
of winter. The brightest star in Canis Major also is the brightest in the entire night sky —
brilliant Sirius, which is just 8.6 light-years away. That's only twice as far as our closest stellar
neighbor.
From: http://stardate.org/nightsky/constellations/
Taurus and the Pleiades: Taurus is another one of the many animals hunted by Orion, the
Hunter. One of the few first magnitude stars in the sky, the bright Aldebaran sits in the middle of
this constellation. The horns of the bull stretch off to the west, marked by β Tau, traditionally
shared with Auriga, and ζ Tau. In the east of the constellation lies one of the best known open
clusters, easily visible to the eye, the Pleiades (also known as M45 or the Seven Sisters). It is
among the nearest to the Earth of all open clusters, probably the best known. The cluster is
dominated by young, hot stars, up to 14 of which can be seen with the naked eye depending on
local observing conditions. YOUR SKETCH OF TAURUS MUST INCLUDE THE
PLEIADES.
From: http://en.wikipedia.org/wiki/Pleiades_%28star_cluster%29
Gemini: Gemini is easy to find as it glides high overhead in mid-winter, above and to the left of
Orion. It's two brightest stars — Castor and Pollux — represent the mythological twins brothers
of Helen of Troy. Pollux is the brighter of the twins. It's a giant star that's about 35 light-years
from Earth. Castor consists of six stars — a cosmic sextet locked in a gravitational ballet. This
crowded system lies about 50 light-years from Earth.
From: http://stardate.org/nightsky/constellations/
Ursa Major: The great bear is always above the horizon in the northern latitudes, but the best
time to see it is in the spring when its high above the northeastern horizon. Ursa Major is best
known as the home of the Big Dipper. Of all the star patterns in the sky, the Big Dipper is the
most universally recognized. The dipper's seven bright stars form a portion of the great bear. It's
hard to see the rest of the bear, especially from light-polluted cities.
From: http://stardate.org/nightsky/constellations/
Suggested Constellations:
Note: You may choose any constellation that is fully visible – make sure that you choose one
that is not hidden behind trees!
Cassiopeia: Cassiopeia, the Queen, is visible in the Northern Hemisphere all year long.
Cassiopeia is known as the Celestial W when below the pole and the Celestial M when above it.
From: http://www.astronomical.org/portal/
Canis Minor: The little dog is said to represent one of the dogs following Orion the hunter.
Canis Minor is a small constellation mainly consisting of the two stars, Procyon and Gomeisa.
Procyon is the eighth brightest star in the night sky.
http://en.wikipedia.org/wiki/Canis_Minor
Auriga: Auriga, the celestial charioteer, has neither chariot nor horse. Instead, he's drawn as a
man holding the reins in his right hand, with a goat on his left shoulder — the star Capella —
and two baby goats in his left arm. Look for him high in the southern sky in January and
February. Capella is one of the few bright stars that is yellow, like our Sun. The light from
Capella actually comes from two separate stars. Both are yellow, and both lie about 43 lightyears from Earth. Each star emits dozens of times more light than the Sun.
From: http://stardate.org/nightsky/constellations/
Leo: In Greek mythology, this constellation was identified as the Nemean Lion, which was
killed by Herakles during one of his twelve labours, and subsequently put into the sky. Leo
contains many bright stars, such as Regulus, the lion's heart, and Denebola.
From: http://en.wikipedia.org/wiki/Leo
LOG PAGES
Observing conditions (cloud cover, temperature, etc.): __________________________
______________________________________________________________________
Constellation Name: _______________________
Altitude: ___________________ Azimuth: ___________________
Which direction do you face to see the constellation? (circle one) North South
Sketch:
East
West
Constellation Name: _______________________
Altitude: ___________________ Azimuth: ___________________
Which direction do you face to see the constellation? (circle one) North South
East
West
East
West
Sketch:
Constellation Name: _______________________
Altitude: ___________________ Azimuth: ___________________
Which direction do you face to see the constellation? (circle one) North South
Sketch:
Constellation Name: _______________________
Altitude: ___________________ Azimuth: ___________________
Which direction do you face to see the constellation? (circle one) North South
East
West
East
West
Sketch:
Constellation Name: _______________________
Altitude: ___________________ Azimuth: ___________________
Which direction do you face to see the constellation? (circle one) North South
Sketch:
Constellation Name: _______________________
Altitude: ___________________ Azimuth: ___________________
Which direction do you face to see the constellation? (circle one) North South
East
West
East
West
Sketch:
Constellation Name: _______________________
Altitude: ___________________ Azimuth: ___________________
Which direction do you face to see the constellation? (circle one) North South
Sketch:
QUESTIONS
Please complete the following table. Do not include the Pleiades when counting the total
number of stars in Taurus or when counting the number of visible stars in Taurus.
Constellation
Ursa Minor
Altitude Azimuth Direction Total Stars Visible Stars
43
0
North
6
Ratio Visible:Total Stars
6
1.
2.
3.
4.
5.
6.
1. Do you notice a pattern between the ratio of visible to total stars in a given constellation, the
direction faced, and the altitude?
2. What could cause such a pattern?
1