What is SMAS?
The Southwest Montana Astronomical Society
is a regional astronomy club for amateur and professional astronomers and
anyone who loves the sky. It's members promote interest in astronomy throughout
the state, sponsoring or co-sponsoring a number of public events as well
as astronomy projects.
Membership is open to all members of the public with any interest in astronomy.
Do I need to own a telescope or know a lot
about astronomy to join the club?
Absolutely not! A lot of what drives the society is its social astmosphere
of FUN and LEARNING about the hobby of stargazing. The club provides a variety
of activities for all levels of interest and experience. Families and older
children are welcome!
When and Where does SMAS meet?
The Society meets on the last Friday of each month (January through October)
at 7:30 p.m. at the Museum of the Rockies, and are always open to the public.
The meeting may include a speaker, demonstration, workshop, telescope viewing,
and updates on current club events. In order to avoid conflict with the
holidays, the November-December meetings are combined
into one on the first Friday of December.
What main events does the club sponsor?
Every year SMAS holds two state-wide events. The annual Montana Astro Fair,
which takes place in winter, is an exciting blend of seminars, planetarium
shows, workshops and displays. Daytime and night observing sessions are
part of the activities. Held in conjunction with the Museum of the Rockies,
it is an event well worth attending. During the summer, SMAS hosts the annual
Montana Starwatch, a weekend campout of dark sky observing that features
guest speakers, daytime activities, a BBQ, door prizes and other activities.
Attendees come from all over the country.
Other common activities of SMAS include informal stargazing at the museum
or at dark-sky sites, a winter astronomy lecture series, family campouts,
workshops on choosing, using and making telescopes, observing techniques
seminars, "sidewalk astronomy" events, and technical projects.
How do I become a member of SMAS, and what
are the benefits?
There are dues which are used to cover the cost
of Society functions. For only $15 single or $20 family, a year you can enjoy the following benefits:
* Our expanded quarterly publication, The Star Wrangler.
* Updates (posted on our website) that come out in between newsletter releases
to keep you notified of current meetings and events.
* Free or discounted access to SMAS functions.
* Automatic membership in the Astronomical League.
* Access to the club's telescope loaner program.
* Voting privileges.
* Subscription discounts to Astronomy and/or Sky & Telescope magazine.
NOTE: These are paid in May when SMAS dues are
collected. Current rates: Astronomy = $29.00 (1 yr) or $55.00 (2 yrs), Sky & Telescope = $32.95
What is the telescope loaner program?
Many members of the club have their own telescopes, but if you don't have
one or are thinking about buying one and want to "try some on for size,"
SMAS has a loaner scope program for its members. We have a wide range of
scopes to accommodate everyone from beginners to experts! There are several
telescopes available, of varying apertures, that can be checked out for two weeks (or more) at a time, depending on availability. For more information, call David Binnewies at 994-6891 (Email: dbinnewies@montana.edu).
What telescopes can I check out?
Newsome Scope: This 4" Criterion reflector was donated for club use
by
Bill Newsome, and restored to working order by himself and Don Nisewanger.It
is equatorially mounted, and has a clock drive.
Roby Scope: This 6" reflector on a Dobsonian mount was built in 1946
by Robert Grasmehr, was donated to the club by his sister, Lois Roby. It
was restored and placed on a new mount by SMAS in 1996. A TelRad finder
is included on this tube.
Moss Scope: This is a 10" reflector on a Dobsonian mount, with parts
collected and donated by SMAS, "Night Skies" telescope store,
and the Museum of the Rockies. It was finished by the Moss family in 1997.
Gorski Scope: Wayne Gorski acquired this 13.1" Dobsonian reflector
and has placed it on permanent loan to the club. It was recently rebuilt
by club members Erik Green and Shane Larson into a collapsible truss-tube
structure, to make it easier to transport, but it is still considered "large"!
What is the largest telescope the club has?
SMAS and the Museum of the Rockies were the joint benefactors of a donation
from the Testamentary Trust of Laura D. Pasley in 1997. The estate's gift
is to provide a portable telescope system of large aperture to further astronomy
outreach and education with children in southwest Montana. A 20" Starplitter
II Dobsonian telescope made its public debut at the 1998 Montana Starwatch,
and is being used at special "star parties." While this scope
is not considered a "loaner," club members can have access to
it by completing a short training session and participating in the club's
educational outreach programs.
What if all I want to do is stargazing?
Members are free to pursue whatever services the club offers, even if it's
just to observe. Star parties take place (weather permitting) after each
general club meeting at the Museum of the Rockies, but also at special times
and places announced by the club. Some may be held in other towns around
the area (Three Forks, Big Timber, Belgrade, Livingston, BigSky,Townsend,
etc.) or simply at someone's home.
GENERAL OBSERVING AND ASTRONOMY
F.A.QS.
1. What is meant by "Right Ascension"
and "Declination"?In reading star
maps, coordinate lines are often drawn in and refer to Right Ascension (R.A.)
and Declination (Dec.). These are simply astronomical "buzz-words"
for sky longitude and latitude. They are very much like Earth longitude
and latitude; in fact, they are based on Earth's coordinates. Imagine extending
the equator and poles of the Earth out onto the sky -- if you could mark
them with something visible, you would see the celestial poles and celestial
equator.
2. What do the symbols ( ' ) and ( " ) mean
when measuring angles?Angular measure on the
sky is a useful way of describing how big an object looks or how far apart
two objects may appear. For example, the width of the Moon in the sky subtends
about 1/2 degree as seen by the eye (An aspirin tablet held at arm's length
covers about the same width!). The height of the north star above the northern
horizon is between 45 and 49 degrees for Montana observers.
A degree can be divided into smaller increments,
and comes into play when telescope viewing since the field of view is often
covering only a fraction of a degree. Think in terms of time:
60 minutes of arc (60') = one degree
60 seconds of arc (60") = 1 minute of arc (1')
These units can be used in describing Declination,
but do not confuse the "hours" and "minutes" of Right
Ascension with this. Right Ascension really IS related to time -- specifically,
the rotation of the Earth. If you need to know the angles when reading maps,
the relationship for Right Ascension is:
1 Hour of Right Ascension = 15 degrees
1 Minute of R.A. = 1/4 degree = 15 minutes of arc (15')
3. Why use binoculars?
Even if you have a telescope, binoculars can be
an invaluable aid to locating and viewing sky objects. Their low power combined
with wide field of view makes them the ideal scanning instrument -- things
look right side up and it's easy to find what you point at! Plus you get
to use both eyes, thus your power of resolution and ability to detect faint
objects are dramatically improved. Color perception and contrast are enhanced
as well. Binoculars make an excellent intermediate step between naked eye
and telescope viewing. They can help you locate those small, dim objects
so you know where to point the telescope later. However, keep in mind that
binoculars can show celestial details that many people think require a telescope.
4. What is meant by "averted vision
technique"?
When viewing through binoculars or telescopes,
most deep sky objects look like faint fuzzy blotches of light - at first.
The ability of the human eye to see intricate detail even in faint objects
is truly impressive if one takes the time to develop the needed observing
skills. First and most important is to make sure the observer is DARK ADAPTED.
This means setting
up in a dark-sky site with no white lights (streetlights, car headlights,
porch lights, flashlights) in view. The pupils in the eye take a minimum
of 15 minutes to fully dilate and thus adjust to see faint details in the
dark.
Now you are ready to use AVERTED VISION
to discern fine details on astronomical objects. When viewing through the
eyepiece, look not only directly at the subject but around the edges or
even slightly off to the side. Slowly look back and forth and around it
in this manner, and finer details will seem to flicker in out of the "corner
of your eye"! This is happening because your peripheral vision is more
sensitive to faint light than your direct vision, which is more constantly
used. To preserve your night vision, use a red-filtered flashlight to read
star maps or find your way around.
5. What is a light year?
Its name implies it has to do with time,
but it is actually a measure of distance. Because objects beyond the solar
system are so immensely far away, 'miles' becomes too small a unit. It becomes
necessary to use a larger scale.
The light year is the distance light will
travel in one year. At 186,285 miles per second, a beam of light will travel
nearly 6 trillion miles in one year (5,878,700,000,000 miles to be exact).
With this scale, we would say that the nearest star to our Sun (called Alpha
Centauri) is 4.3 light years away.
Compare this with light-speed distances
to these objects:
Moon 1.3 light seconds
Sun 8 light minutes
Pluto 5.2 light hours
Sirius (brightest star) 8.7 light years
Polaris 652 light years
Center of Milky Way 30,000 light years
Andromeda Galaxy 2.2 million light years
Virgo Cluster of Galaxies 62 million light years
Typical Quasar 3-5 billion light years
Edge of Visible Universe Over 10 billion light years
6. Is it possible to see planets or stars
during the day?
In general, the answer is no. The only
celestial object besides the Sun which is normally visible during the day
with the unaided eye is the Moon, and even that is easy to overlook. But
for several months each year, the next brightest object, Venus, is dazzling
enough to be seen with the unaided eye in broad daylight. However, actually
seeing Venus this way means waiting for the right time and knowing exactly
where to look.
7. What is meant by "magnitude"?
Magnitude refers to the brightness of
an astronomical body. Apparent magnitude 1 is exactly 100 times brighter
than magnitude 6, each magnitude being about 2.5 times brighter than the
next. Magnitudes brighter than 0 are minus figures, thus Sirius is -1.4,
and the sun is -26.8. The faintest objects yet photographed are about magnitude
+29. For simple backyard
observing, see the following chart:
-4 Venus at maximum
-3
-2 Jupiter at maximum
-1
0
+1
+2 Downtown city limit
+3 Limit in suburbs
+4
+5 Limit in rural areas
+6 Naked eye limit under best conditions
+7
+8
+9 7 X 50 binocular limit
+10
+11 4-inch telescope limit
8. What is meant by "open cluster"
and "globular cluster"?
These are physical groupings of stars
in space, moving together as a unit. They were all formed together at the
same time, but there is a big difference between "open" and "globular"
in size, age, numbers and types of stars:
Open clusters are loose gatherings of
stars, usually numbering from the tens to the hundreds. They are usually
quite young, from the tens of millions to hundreds of millions of years.
They may be so young that some of the dust and gas (nebula) that formed
them may still be present. Found in our galaxy's spiral arms (like the sun),
most open clusters dissociate, finding their own indivual orbits about the
center of the Milky Way.
Globular clusters are much larger, spherical
groupings. Numbering in the hundreds of thousands to millions of members,
these clusters contain some of the oldest stars in the galaxy, up to 12
billion years in age. Because of their great numbers, they stay intact as
a cluster their entire lives. Globulars orbit the Milky Way in a spherical
halo around the central bulge of our galaxy, thus they are usually quite
distant from the earth (tens of thousands of light years). Over 160 globulars
are known to exist in our galaxy.
9. What is a nebula?
The Milky Way is not just made of stars.
The space between the stars has gas and dust, and in some places concentrations
of this material can be found in clouds called nebulas. Some clouds that
we see glowing are Emission Nebulae, glowing to fluorescence due the radiation
of nearby stars. Some of those that glow may exhibit an obvious ring or
circular shape, called Planetary Nebulae; these are the leftover remains
of a dying star which has puffed away its outer atmosphere into a shell
of gas. Other clouds, however, emit no light (Dark Nebulae) and can act
as curtains hiding the more distant stars from our sight. In the summer
Milky Way, an
apparent dark lane can be seen dividing its faint band right down the middle.
This is in fact enormous amounts of dark nebulosity hiding the thousands
of stars beyond.
10. What's the difference between "solar
system," "galaxy," and "universe"?
A solar system is just a star (like our
sun) whose gravity holds planets, asteroids, comets and meteoroids in orbit
around itself. Each other star we see in the night sky is potentially another
solar system.
A galaxy is a vast island of hundreds
of billions of stars (solar systems), nebulas and star clusters. Our Milky
Way has over 200 billion stars in a spiral shape, over 100,000 light years
wide.
The universe encompasses all the galaxies
-- billions of them, some coming in clusters of their own. At the edge of
the visible universe we see bizzare, super-energetic objects called Quasars,
the fiercely eruptive cores of young galaxies.
11. Why can I sometimes see the moon in
the daytime?
It is not uncommon for people to be surprised
at the appearance of the moon in the daytime. The moon, in fact, CAN be
seen quite easily at times because it is still sufficiently brighter than
the bright blue sky caused by scattered sunlight. The stars are still there
too, only their
brightness is too low to overcome the skyglow.
The moon is always moving in orbit around
the earth, thus it's constantly changing position in the sky relative to
the sun. At certain periods it will be at a position alongside the sun,
sometimes small and difficult to see (crescent), sometimes almost full (gibbous),
but visible nonetheless if one takes a moment to search.
12. Why does the moon look so big when
it's rising?
Almost everyone has noticed the same effect:
the moon indeed appears larger when it is close to the horizon than when
it is overhead. Yet you can prove to yourself that this is strictly an illusion.
Hold a dime at arm's length in front of the moon. Regardless of the moon's
elevation in the sky, the dime will just cover it.
The "moon illusion," as it is
sometimes called, is entirely conjured up by the human brain. There are
still several explanations for what the actual process might be -- some
contend it's brought about by having terrestrial frames of reference right
near the moon when its rising (trees, houses, telephone poles, etc.), allowing
the brain to "focus" on it more closely.
Another theory says the illusion centers of the human perception of the
sky as an overturned bowl, more distant on the horizon than overhead, which
fools the brain into "correcting" the size of the moon for that
scenario. In any case, here is a final test to prove that it's all in the
mind. When no one is watching and the full moon is near the horizon, bend
over and
look at the moon upside down from between your legs (!). The effect vanishes,
presumably because you have flipped the scene reaching the brain by placing
the horizon above the moon.
13. Why do stars twinkle?
Stars appear to twinkle because they are
pinpoint sources of light. In reality, of course, the stars are far from
tiny, but their enormous distances from earth reduce them to dimensions
so miniscule that even the largest telescopes are unable to reveal them
as disks. They are mere point sources. Thus a beam of light from a star
entering your eye is a fragile thread that is easily rippled by the ever
present turbulence in the earth's atmosphere, which causes the twinkling.
You might notice that planets, on the
other hand, do not twinkle (or at least not nearly as much as the stars).
This is because planets do notappear as pinpoints, they appear as tiny disks
since they are much closer than the stars. The bigger bundle of light from
the planet is less easily disrupted by atmospheric turbulence.
14. When is the best time to look for
the Northern Lights?
On certain occasions, the northern night
sky is alive with dancing, luminous curtains of red, green, purple or yellow
light, swaying and pulsating and sometimes converging near the zenith (overhead).
Experiencing such a display of northern lights, or aurora borealis, is like
standing inside nature's kaleidoscope. Some of the largest displays can
surge trillions of watts through the high atmosphere, creating an unforgettable
experience from a dark sky location.
Dazzling all-sky auroras have been seen
by few people, but lesser displays are visible several times a year from
mid-northern latitudes. The fact is, our indoor television-oriented culture
in combination with modern outdoor lighting mean that many people have never
seen an aurora at all. Some displays can, however, be seen from the city.
Auroras peak and subside in harmony with
the 11-year sunspot cycle. The last sunspot maximum was in 1991, and spectacular
all-sky auroras were visible in March 1989, March 1990 and November 1991.
In between maxima, auroras are less frequent and less intense, although
an impressive show can still occur. Specific predictions are impossible.
There is no favored time of night, although the strongest displays seem
to occur in March, April, September and October. The only way to see an
aurora is simply to go outside every clear night and look for an unusual
brightening in the northern sky.
Ranging from a pale greenish white glow
near the horizon to intense red, green and blue spears and curtains that
fill the sky, auroras magically float among the stars. The phenomenon originates
when eruptions on the sun's surface, called solar flares, liberate vast
amounts of charged particles into space. The charged particles -- actually
just parts of normal atoms -- reach earth, follow our planet's natural magnetic
field and are funnelled into a continent-sized ring around the magnetic
north pole in Canada's Arctic (a similar ring occurs over Antarctica).
The interaction between air molecules
60 to 500 miles above the surface and the incoming solar-charged particles
releases energy in the form of light, making the earth's upper atmosphere
act like a glowing television screen. This happens all the time, but usually,
it is dim or the auroral ring is too far north to be visible from the more
populated parts of Canada and the U.S. When solar activity increases and
more particles reach earth, the aurora brightens, the ring expands to the
south and display may become visible to millions.
15. Why don't you see color when observing
sky objects in a telescope?
Many times we see astro photographs that
reveal a variety of deep colors in most deep sky objects, yet when we look
at them through a telescope they usually show a faint gray or bluish haze.
This has to do with the way our eyes sense light. The retina contains sensors
called rods and cones. Rods detect black and white, and are seven times
more sensitive than the cones, which detect color. Ever noticed that when
you're in a room with very low light, that it's difficult to discern any
colors? Just remember that when the rods are dark adapted, the level of
fine detail that can be picked out can truly be amazing!
16. If the stars are always like pinpoints,
why do the brighter ones look bigger?
This is another physical effect the eye
plays on you - the brighter stars actually measure the same in angular size,
but due to their greater brilliance they activate some of the nearby sensors
in your retina and cause your brain to interpret it as being "larger."