Deep Space Objects
OBJECTIVES:
1. Students will be able to locate
nebulas, double stars, clusters, variable stars, and galaxies (in the StarLab).
2. Students will be able to describe
nebulas, double stars, clusters, variable stars, and galaxies.
3. Students will be able to describe
the location of “Mizar and Alcor” (a double star pair).
RELATION TO MISSOURI FRAMEWORKS:
9-12: VA2 Stars appear to go through a cycle
of birth, development, and death.
9-12: VA3 Because of the vast distances between objects in the universe, light may take billions of years to reach Earth.
9-12: VB1 Newton’s conception of the universe established the idea that the laws, which apply to processes that occur on the Earth, also apply to the universe.
9-12: VC1 Space
exploration has expanded our knowledge of the universe and advanced the
technological sophistication of our society.
CONTEXT:
Group
of 15-25 for StarLab presentation
PREREQUISITE:
The students should have an understanding of stars and
constellations.
MATERIALS:
Starfield
and Deep Space Objects Cylinders
Arrow pointers
Red Flashlight for reading text
PROCEDURE:
1. When
all students are seated, begin to ask questions to gauge their previous
knowledge as their eyes get used to the darkness. “What are stars?” “What
are constellations?” “Can anyone name a
constellation?” “Can anyone find a
constellation in the night sky?”
2.
As the questions are
asked and answered begin to turn up the StarLab lamp with the Starfield
Cylinder in place. “This is a
simulation of the night sky if it is viewed away from the city.” “What are we viewing?” [Stars]
“Who can pick out any constellations here?” (Pass the pointer to a volunteer.)
3.
“Let’s change cylinders
to get a different view of the night sky.”
Turn down the lights and change to the Deep Sky Objects Cylinder. As you bring up the lamplight, “You just
indicated that we were looking at stars in the night sky. What do you see now?”
4.
Indicate to the students
that the symbols stand for different objects in the universe, many of which are
outside of our galaxy, or are just too far away to be seen without binoculars
or a telescope. The star shapes
represent nebulae, diamond shapes are variable stars, triangles are double
stars, rectangular boxes are galaxies, and square shaped objects represent
clusters. [Point out the location of one or two during the explanation of
symbols.
5.
Explain what each of the
objects is and how studying it has helped in furthering understanding in the field of Astronomy.
Nebulae: An accumulation of gas and dust. Usually about 90% Hydrogen, 8% Helium and 2%
other elements. Studying Nebulae have increased astronomers understanding of
the life cycle of stars. These are the
birthplace of stars. Gravity pulls the
gasses together until the added pressure causes fusion. Nebulae can also be related to the death of
stars. As stars lose mass, its
gravitational pull is reduced and gases are lost to the surrounding space.
Double Stars:
Even though we normally see one point of light with our eyes, more than half of
the stars in the Milky Way Galaxy are actually twins. That makes our sun part of a galactic minority. These double stars appear to revolve around
each other, but in reality orbit a common center of mass between them.
One of the best known and easiest to find pairs are
“Mizar” and “Alcor.” These two stars
make up the “second star” in the handle of the Big Dipper.
Variable Stars: Though most stars give off a relatively
constant amount of energy (light), some appear to change brightness on a
regular basis. Some change brightness
because of mutual eclipses of double stars.
Others are stars, which actually change in size and temperature. These stars are thought to be near the end
of their life cycle and vary in brightness because their fuel is nearly
exhausted.
Clusters:
Because they form from nebulae, stars seldom form alone. Instead, they form in groups, associations,
and clusters. Gravity is the deciding
factor for all clusters. If the gravitational
force is weak, the stars drift apart forming an open cluster. [The Big Dipper
of Ursa Major is an association of stars (open cluster) that is drifting
apart.] There are two types of clusters, open clusters that are thought to be
relatively young on the cosmic time scale, and globular clusters, which are
thought to be the oldest stars in the galaxy.
Galaxies: All
the stars, clusters, and nebulae seen with the unaided eye are part of the
Milky Way Galaxy. The Milky Way is just
one of millions or perhaps billions of galaxies in the universe. The locations of many of these galaxies have
been known for decades. When we leave,
you will receive a handout that will show the locations of many galaxies that
are visible with binoculars.
6.
“Why can’t the Andromeda
Galaxy or other Deep Sky Objects be viewed with the naked eye?” [Because of
their great distances, they are too dim to be seen.]
7.
“Who can point out and
describe a nebula; double star; variable star; cluster; galaxy?”
8.
Let’s go outside where
you will have a short evaluation and get your “Sky Map” so you can look for
some of these objects at home. [Bring up the side lamps and turn down the
projection lamp so students may exit the StarLab.]
REFERENCE:
1. The
Talcott Mountain Science Center, “A Look at the Deep Sky Cylinder,” Astronomy
and More: Activities for the StarLab Portable Planetarium.
2.
Kratzer, Gary D., “Deep
Sky Objects: Activity 1,” Astronomy and More: Activities for the StarLab
Portable Planetarium.
3.
Anonymous,
“Celestial Objects: Northern Hemisphere, July, 2000,” 2 pages. Available: http:www.skymaps.com/store [July
27, 2000]
EXTENSIONS AND/OR ADAPTATIONS:
Upon completion of the evaluation sheet, pass a list
of Deep Sky Objects and Sky Maps to the students. Ask them to try to find any of the objects listed in the sky this
evening. (Remember, most require
binoculars or a telescope.)
CONTENT BACKGROUND:
Because of the vast distances between objects in the
universe, our view of the night sky is limited by sensitivity of our
sensors. When viewing the sky with our
eyes, we are limited in our ability to gather and focus light. Because of these limitations, humans can
only see the celestial objects, which appear bright. These objects usually appear bright because they are close. Every star like object we can see with
the unaided eye is in our own Milky Way Galaxy. There is a vast universe beyond The Milky Way, as well as faint
objects within the Milky Way that are normally too dim to see without
magnification. Objects such as Nebulae,
Double Stars, Clusters, Variable Stars and other Galaxies.
APPENDIX:
1.
Post activity evaluation
sheet.
2.
Sky Map for the
month with the celestial objects listed.
WEB SITES:
www.britannica.com/bcom/eb/article - (online
encyclopedia)
www.sciam.com/1998/1098issue/1098laham.html - (online
periodical)
www.cobweb.nl/bertyvon/index.html - (Images and
descriptions of Deep Sky Objects)
www.skymaps.com/store (Monthly maps of the night sky
with glossary)
Provide an
accurate description for each of the
following Deep Sky Objects. As a bonus,
how has the study of any of the those objects increased mankind’s knowledge
of star life cycles and/or star masses.
Nebulae
Double Stars
Clusters
Variable Stars
Galaxies
What are “Mizar” and “Alcor” and where can they be
found in the night sky?