Download Sky News 2009-2011 - lethbridgeastronomysociety.ca

Lethbridge Astronomy Society
Lethbridge Herald Articles
2009 – 2011
1
International Year of Astronomy
By Rena Woss
Lethbridge Astronomy Society
2009 is International Year of Astronomy!
This first ever global effort was initiated by the International Astronomical Union
and UNESCO to help citizens of the world rediscover their place in the Universe
through connecting with the day and night-time sky, so that all of us might
engage in a personal sense of wonder and discovery. At a local level, the
Lethbridge Astronomy Society will be hosting special events throughout the year
with this goal in mind. We are all a part of the grandeur and magnificence of the
universe. It is our hope that citizens of our community will visit our Observatory and take in the
many and varied events we have planned. It is our wish that each and every one of you will
directly experience the many wonders that the universe. Visit our website and watch for
upcoming events and articles. Let’s make this year a year of cosmic celebration!
2
Good morning, Venus!
By Gord Falconer
Lethbridge Astronomy Society
Since last autumn, our western sky displayed a dazzling “evening star”,
which was actually the planet Venus – far brighter than any real star.
Lately, it has been invisible because on March 27, Venus passed
between the Earth and the Sun. Soon, Venus will be visible again as
the “morning star”. This naturally occurs as it emerges from the Sun’s
glare and rises before the Sun each morning. For you early risers, have
a look towards the East as the dawn sky brightens. See how soon you
can spot Venus. After that, watch for it every chance you get. Each
day it will be higher and higher in the pre-dawn sky. By June, it will be
rising in a dark sky, and will be easy to see by the time the sky brightens too much.
Photo: NASA apod.nasa.gov
3
May 1, 2009
See Saturn's Rings!
By Alan Dyer TELUS World of Science, Calgary
and honorary member of Lethbridge Astronomy Society
Yes, you really can see the rings of Saturn. You'll
need a telescope (any will do), or the help of a
friendly telescope-equipped neighbor! This spring is
the best time in 2009 to see the ringed planet,
appearing as the brightest star high in the south at
nightfall in April and May. A telescope at 50 to 100 power (no need to use more magnification
than that) will reveal the rings as sharp spikes of light sticking out on either side of the planet.
That's an unusual appearance for the planet because this year Saturn's rings are tipped almost
edge-on to our line of sight, something that happens only every 15 years. The Lethbridge
Astronomy Society is a wonderful resource to connect with the universe.
Photo: JPL Solar System Simulator
4
Andromeda Galaxy
By Rena Woss
Lethbridge Astronomy Society
The universe contains trillions of vast islands of stars
that we call galaxies. One of the easiest and most
rewarding to observe is Andromeda. At 2.5 million
light years away, it is one of our closest galactic
neighbors. Andromeda is so large and bright that on
a moonless night, away from the glare of city lights,
you can actually see it with your own eyes as a faint smudge in the night sky. In the city, a pair of
binoculars will help you easily find it. As you can see from this picture, Andromeda has a beautiful
spiral shape to it, much as we imagine our own Milky Way galaxy to have. It is named after a
princess in Greek mythology, and can be found in the constellation of Andromeda. Visit us at the
Lethbridge Astronomy Society the last Saturday of the month (September to March) to see
Andromeda and many other celestial wonders of the night sky.
Photo: Norm Baum and Jack Newton
5.
Enchanted by a Lunar Eclipse
By Gord Falconer
Lethbridge Astronomy Society
In some sense, Earth is just a big round rock orbiting
the Sun. Like other rocks, it casts a shadow on a sunny
day. Earth’s shadow is cone-shaped and projects over a
million kilometers into space. Our Moon which is about
385,000 km away is well within range of Earth’s
shadow. How does an eclipse occur? During a Full Moon, the Moon usually passes above or below
the shadow; but sometimes, it passes partially or directly into the path of Earth’s shadow. When
this alignment occurs, we call it a lunar eclipse. One of the things you will notice during a lunar
eclipse is how the moon’s colour changes. From its normal dazzling silvery white, it increases in
darkness as it makes its way into Earth’s shadow. It never goes completely black, but rather turns
a darkish copper penny red. This is due to sunlight scattering from Earth’s atmosphere onto the
Moon. After a short while, the Moon emerges out of the shadow and returns to its full brilliance.
Lunar eclipses are fairly common and easy to view - just look to the sky!
Next partial lunar eclipse visible from Lethbridge:June 26, 2010
Next total lunar eclipse visible from Lethbridge: Dec. 21, 2010
Photo: Rena Woss
http://eclipse.gsfc.nasa.gov/eclipse.html
http://en.wikipedia.org/wiki/Lunar_eclipse
http://www.lethbridgeastronomysociety.ca/
6.
Treat Yourself to a Summer Star Party
By Rena Woss
Lethbridge Astronomy Society
Summer is around the corner and during this time of
the year, astronomy clubs the world over have
outdoor gatherings called Star Parties! If you have
never attended, you might want consider it. It’s an
opportunity to experience the splendor of the night
sky with people who have a passion for it. Typically
star parties are held in a dark sky site, away from
light pollution. Participants bring telescopes
and binoculars of all types and sizes and spend the nights observing planets, galaxies and other
deep sky wonders. Larger parties offer lectures, work shops, swap meets, exhibitions, contests,
tours and more.
A wonderful party to attend is the Saskatchewan Summer Star Party hosted by the Royal
Astronomical Society of Canada - Saskatoon and Regina Centre’s on August 13th to 16th, 2009 at
the Cypress hills dark sky preserve.
For more information http://homepage.usask.ca/~ges125/rasc/starparty.html
Photo: Alan Dyer
7.
The Magic of a Total Solar Eclipse
By Gord Falconer
Lethbridge Astronomy Society
At New Moon, the alignment of Sun, Moon and Earth isn’t perfect; the
Moon But occasionally, the Moon passes directly in front of the Sun; in
effect, the Moon casts its shadow on the Earth. If you are in the
shadow, you may see the Sun, with a safe solar filter, partially
eclipsed; it looks as if a bite has been taken out of the Sun.
If you are lucky enough to be on the narrow strip of Earth where there is a total eclipse, the Moon
completely blocks the Sun for a few minutes; the sky darkens, and the beautiful solar corona,
otherwise invisible, can be seen. These rare and beautiful events are among nature’s most aweinspiring. Don’t miss an opportunity to see one.
Next partial solar eclipse visible from Lethbridge: May 20, 2012
Next total solar eclipse visible from Lethbridge:
Aug. 23, 2044
Next partial solar eclipse visible from Lethbridge: May 20, 2012
Next total solar eclipse visible from Lethbridge:
Aug. 23, 2044
Photo: Murray Paulson
http://eclipse.gsfc.nasa.gov/SEmono/TSE2009/TSE2009.html
http://www.lethbridgeastronomysociety.ca/
8.
Myths of the Heavens
By Rena Woss
Lethbridge Astronomy Society
The 88 constellations that make up the night sky are rich
with mythology and folklore. It’s not hard to guess why.
Imagine living a thousand years ago, tending a flock of
sheep alone, out on some lonely plain, or having to
traverse a desert or ocean with your silks and spices on
route to a new market? Camping under a dark night sky
ablaze with stars, planets and occasional meteors could
make for a daunting experience. No wonder people
connected stars into patterns and made up stories
about the constellations. It’s much easier to travel with
sky companions that you are familiar with than leave
yourself open to fear and wonder. Every culture created
mythology around the night sky. Becoming familiar with the stories makes for a wonderful way of
connecting to ancient cultures, and it’s helpful in remembering the names, shapes and locations of
the constellations.
9.
Moon’s Monthly Orbit
By Klaus Jericho
Lethbridge Astronomy Society
Our Moon goes around the Earth in an elliptical
orbit, at an average distance of about 385,000
km. At is closest, it is about 356,000 km away; at
its furthest, about 405,000 km.
A ‘moonth’ (taken from medieval English) was the
time it took the Moon to go once around the Earth.
Dividing 360 degrees of a circle by 30, we find that the
Moon moves about 12 degrees each 24-hour day,
against the background stars in the sky. If you hold
your fist at arm’s length, its width will occupy an angle
of about 12 degrees. So – if you carefully note the
position of the Moon against the background stars
some evening, hold your fist out so that the right side
of your fist touches the Moon. Look at the stars by the left side of your fist. That’s where the
Moon will be tomorrow night. Try It out!
10.
Understand Lunar Phases
By Klaus Jericho and Gord Falconer
Lethbridge Astronomy Society
The Moon is a big round ball of rock 3460 km in
diameter. It doesn’t emit any light of its own
(neither does Earth), but rather ‘shines’ by the
sunlight it reflects toward us.
Half of the Moon is always lit by the Sun. But
sometimes the illuminated half faces away from
Earth while the unlit side faces us, and we cannot
see the Moon at all. This is the ‘New Moon' phase. Two weeks after New Moon, the illuminated
half faces us, and we see the familiar and bright Full Moon.
Between New Moon and Full Moon, the angle between the Sun-Moon line and the Moon-Earth
line continually changes as the Moon orbits the Earth. This is why we see the Moon increasing and
decreasing in size and shape. A Lunar Month refers to a cycle of phases from New Moon, to
Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last Quarter,
Waning Crescent and back to New Moon.
11.
Phases of the Moon Experiment
By Klaus Jericho and Gord Falconer
Lethbridge Astronomy Society
Try this experiment. Pick up a book, and label the front cover ‘near side’, the rear cover ‘far side,
the open side (on the right) ‘First Quarter’, and the spine ‘Last Quarter’. Go outside on a sunny day
and face the Sun. Hold the book at arm’s length in front of you, with both hands, with the ‘near
side’ facing you. This is the New Moon phase.
Notice that the far side is brightly lit by sunlight, while the near side is in shadow.
Now, turn your whole body to the left, keeping your arms out. At 90 degrees, notice that the open
side of the book (‘First Quarter’) is illuminated. Keep turning left. Notice that at 180 degrees the
near side is fully lit. Keep turning. At 270 degrees, the ‘Last Quarter’ spine is lit. Complete your
circle at New Moon.
Notice something? The ‘near side’ always faces you, but it may be fully, partly, or un-illuminated.
And the far side may be fully, partly or un- illuminated. This explains why it is not correct to speak
of the Moon as having a ‘Dark Side’, in a permanent sense. But it does have a near side and a far
side!
12.
Moon’s History
By Klaus Jericho and Gord Falconer
Lethbridge Astronomy Society
Astronomers believe (based on evidence, reasoning and other
components of the scientific method) that our Moon was
formed about 4.5 billion years ago. The very young Earth was
hit by another object, roughly the size of present-day Mars. The
result was a huge amount of rocky debris thrown up into space
near the Earth. Much of it would have fallen back to Earth; but
a small amount of it (just over 1% of the Earth’s mass) had
enough energy to remain in orbit around Earth.
This debris coalesced into our Moon, at a distance of only a few Earth radii. What a sight it would
have been in the night sky – if there had been anyone to marvel at it!
Ever since then, the Earth and Moon have been engaged in complex interactions of tidal forces.
This is why the Moon today is about 60 Earth radii away and why the Moon’s orbital distance
grows by 4 cm per year.
13.
A Greek Myth for Northerners
By Rena Woss
Lethbridge Astronomy Society
Of the 88 constellations, about two thirds can be seen from the
northern hemisphere. Three of these include royal family of
Ethiopia: Queen Cassiopeia, King Cepheus, and their daughter,
Princess Andromeda. Myth has it, that the queen was ravishingly
beautiful and as sometimes happens, very boastful about it.
After years of putting up with her vanity, the sea nymphs
beckoned King Neptune to teach her a lesson. Convinced, the
sea king summoned the water monster Cetus to devastate the
entire coastline of her domain that was dotted with villages and
lush farm land. After weeks of havoc and suffering, the Queen
and King consulted with an Oracle to advise them of a way to
appease the sea king. They were told that they would have to
sacrifice the most precious thing in their life in order to lift the
curse, and that was their daughter, Andromeda. Horrified and
heartbroken, they realized they had no choice, and at the
appointed hour walked the princess out to the water’s edge, where the sky darkened, and the
waters parted as the monster made its way to devour her. Well as fortune would have it, way up
in the sky a young hero by the name of Perseus was touring the sunny heavens on his majestic
winged horse Pegasus. He noticed the darkening in the earthly landscape and swooped down to
take a closer look, only to see the most beautiful maiden he had ever laid eyes on. He also saw the
sea monster making its way for Andromeda, and in a flash he put it all together. With that, he
dove to Earth and with his magic shield and powerful sword, killed the monster just as it was
lunging out of the water. Perseus rescued the beautiful maiden and restored peace in the
kingdom. The young couple fell instantly in love - got married - and lived happily ever after. The
queen however didn’t fare as well. She too was elevated to the heavens, but is relegated to
forever sit on a throne that is, well – cockeyed to say the least. Not being able to sit in a regal
position was purposely done to remind her of her vanity. The cast of 6 celestial characters can be
seen throughout most of the year for us lucky northerners. All 6 constellations are located close to
the Big Dipper.
http://chandra.harvard.edu/photo/constellations/index.html
14.
ON THE SHOULDERS OF GIANTS
Written by Lloyd Flaig
Lethbridge Astronomy Society
Isaac Newton once said, “If I have been able to see further, it was only because I stood on the
shoulder of giants.”
One of the most influential of giants was the Greek astronomer,
Claudius Ptolemaeus (Ptolemy) who lived circa 100-170 AD. His
published work, the Almagest, remained the most authoritative
work of Astronomy for 1400 years. Following the work of earlier
Greek scientists and philosophers, notably Aristotle, Ptolemy
located the Earth at the centre of the universe with the Sun,
Moon, planets and the stars revolving around it in circles. He
was the first to devise a complex system of “epicycles”, or
smaller circles moving around larger circles, to explain the
complicated motions of the planets.
It took until 1543 to dislodge this widely-held, but mistaken,
view of the universe. Just before his death, Nicolaus Copernicus
(another giant, to be sure) published “On the Revolutions of the
Heavenly Spheres”. Correctly, he showed that the Sun was at the
center of our solar System, and the Earth was just one of the
planets in orbit around the Sun.
http://www.lethbridgeastronomysociety.ca/
15
Seven Sisters of the Night Sky
Written by Melissa Robdrup
Lethbridge Astronomy Society
One of the youngest star clusters in the night sky is the
beautiful blue and white Pleiades (often called the “Seven
Sisters”). This cluster, located in the constellation of Taurus,
formed about 115 million years ago. Astronomers estimate
the Pleiades will remain a cluster for the next 250 million
years, at which point, they will drift apart.
At a distance of 440 light years, this group is the nearest star cluster to earth. It is easily visible to
the naked eye throughout the autumn and winter months. When viewing it with binoculars or a
telescope, you may see fuzzy-looking clouds (nebulosity) around the stars. Technically this is a
“reflection nebula”. Clouds of dust between the stars and Earth are reflecting the stars’ light as it
passes through. Blue light is more easily reflected onwards, hence the bluish colour.
The Pleiades have been mentioned in many books including the Bible, Koran, Greek and Hindu
Mythology and books such as Odyssey. The nine brightest stars in the Pleiades have been named
after the titan Atlas and Pleione and their seven daughters: Sterope; Merope; Electra; Maia;
Taygete; Celaeno; and Alcyone. So when summer comes to an end and the crisp autumn nights
arrive, turn your eyes skyward to the north and gaze upon some of the magnificent stars in the
heavens - the Pleiades star cluster.
16
MEN ON THE MOON (THE EAGLE HAS LANDED)
by Rena Woss and Gordon Falconer
Lethbridge Astronomy Society
Many young people find it hard to believe, but there
really have been men on the Moon. 2009 marks the 40th
anniversary of the first manned Moon landing. The
Apollo 11 Mission launched with a Saturn V rocket from
Kennedy Space Center in Florida, on July 16, 1969. The
world held its breath when on July 20, the Lunar Lander,
“Eagle”, landed on the Sea of Tranquility. Astronauts Neil Armstrong and Buzz Aldrin walked on
the Moon, while Command Module Pilot Michael Collins orbited above. The safe return to Earth of
the crew on July 24 fulfilled President John F. Kennedy’s goal of reaching the moon by the end of
the 1960’s.
Sadly, the last manned Moon landing was in December of 1972. Having won the Space Race, the
United States abandoned further lunar missions, and turned its attention to more pressing foreign
and domestic problems. Lately, there is renewed interest, in the United States and several other
countries, in returning to the Moon, as we will discuss in future columns.
17.
Celebrating the Telescope
Rena Woss,
Lethbridge Astronomy Society
2009 has been declared International Year of Astronomy for it
marks the 400th anniversary of the invention of the telescope.
The person responsible for its creation and particular use was
mathematician Galileo Galilee. To give you some background,
the study of optics started in the thirteen hundreds. It took
the next 300 years of grinding and polishing to perfect the
science from that which focused on spectacles to correct
vision, to lenses that actually magnified objects. Amazingly
enough, in 1608, not one but three Dutch inventors simultaneously created an optic that could
magnify an object 3 times. Referred to as a ‘spyglass’, the invention was an instant sensation and
hit the marketplace a year later. One of the first to acquire one was Galileo, who unlike others,
immediately saw another potential for it and set to work constructing yet a better, more powerful
optic. By November of 1609, his spyglass magnified objects 15 times, and by March of 1610 he had
built another that magnified 30 times! The first object that Galileo looked at was the Moon, and
later Jupiter with its 4 Moons. His observations shook the Church to its foundations which is a
fascinating subject for another episode. Treat yourself to a night under a starry night sky and look
through a telescope or through a pair of binoculars if you get a chance and send Galileo and Big
Thank You.
18.
On the Shoulders of Giants
by Lloyd Flaig
Lethbridge Astronomy Society
Charles Messier (1731 – 1817)
Born in France, Charles Messier was bitten by the astronomy bug when he
saw his first comet at age fourteen. A few years later he witnessed an
annular eclipse. The inspiration of witnessing celestial events led him to
recorded 20 comets; thirteen of which were firsts. His passion for comet
hunting hit a wall each time he found objects resembling comets. To make sure he didn’t mistaken
them as comets, he recorded their locations and compiled a catalogue of them. In all, he listed 110
objects. Unknown to him and other astronomers, the objects he found annoying were some of the
most wondrous of celestial objects - open and closed clusters, nebulae and galaxies of the
northern hemisphere. Ironically, the catalogue is what he is famous for and once a year in March,
amateur astronomers try to observe record all 110 Messier objects from dusk to dawn on a single
night. In his honor an asteroid (7359) and a crater on the Moon (Messier) were named after him.
Look to the Internet for more on the life of this interesting man.
19
A Galileo Moment
By Rena Woss
Lethbridge Astronomy Society
Jupiter is the fifth planet from the sun, and is also the largest, by far, in
our solar system. It takes 12 years for it to orbit the Sun, but its “day”
is very short; it takes slightly less than 10 hours to turn once on its axis.
Because the planet is mostly made of gases hydrogen and helium, its
fast rotation speed has caused the planet to be slightly bulged in the
middle. Jupiter's gravitational pull is also the strongest in the solar
system (not counting the Sun). If you weighed 100 pounds on Earth,
your weight on Jupiter would be around 236 pounds!
You can see Jupiter shining brightly in the constellation of Capricorn throughout August and
September - just look towards the south-southeast as it gets dark. If you own a pair of binoculars
you’re in for an even bigger treat. Jupiter has at least 63 moons; four of these are so they can
easily be seen through binoculars. The moons will appear as 4 sharp points of light, lined up with
Jupiter’s equator. Simply by observing Jupiter and the moons in 2009, you will participate in an
amazing event we call a 'Galileo Moment' for these moons were first observed by Galileo Galilei in
1610. Participate in history - think of Galileo and marvel at the king of the planets.
20
On the Shoulders of Giants
by Lloyd Flaig
Lethbridge Astronomy Society
Nicholas Copernicus 1473 -1543
Nicholas Copernicus was born in Poland where he studied
mathematics at the Krakow University. His interest in astronomy
grew until it became his primary interest. Celestial observations were
made by eyeball from a turret wall around a cathedral, a hundred
years before the telescope was invented. His gift to the world was a
book called ‘De Revolutionibus’ in which he stated that the Earth
orbited the Sun as did all the known planets, and that it revolved
around its axis once a day. This of course was contrary to the belief of the day but it was received
with great interest by many scholars. Curiously, the book might never have been published had it
not been for one of his students, George Rheticus, who added a foreword that the contents were
not to be taken seriously. Copernicus received a copy of it on his deathbed, never knowing what a
stir he had caused with the church and cosmologists. His reluctance to publish was not due to the
fact that it was against the thinking of the Church but mainly because he thought other scientists
should check and recheck his findings. Three years later, in 1546, Giovanni Tolosani attacked the
book, saying it was against Holy Scripture, and six decades later the Church denounced the
publication. Another of his beliefs was that the orbits around the sun were perfect circles, because
God was perfect and would not allow imperfections. While his first premise was correct this was
not. It was German astronomer, Johannes Kepler, that later discoverd the true orbits of the earth
and planets.
On the Shoulders of Giants
by Lloyd Flaig
Lethbridge Astronomy Society
Johannes Kepler 1571 – 1630
Kepler, an astronomer and astrologer, was born in Germany to a poor
Lutheran family. His brilliance was soon recognized and he was sent to
the University of Tubingen to study for the Lutheran ministry. Later he
became a mathematics teacher in Graz where he became enthralled with
the Copernican theory. During the Thirty Years’ War he worked for Tycho
Brahe, a Danish astronomer. Using Brahe’s data he discovered Mars orbit
was not a perfect circle, but elliptical. In 1619 he published his most
important work, “Epitome”, explaining correctly the elliptical system of
planetary orbits. Kepler considered “Harmonia Mundi” to be his most
important work in which he explained mathematics, music, astrology and astronomy fit into the
divine plan of creation. He believed in harmonics of the orbits of planets and worked at it for the
rest of his life.
On the Shoulders of Giants
by Lloyd Flaig
Astronomy Society
Lethbridge
Galileo Galilei 1564 – 1642
“I do no feel obliged to believe that the same god
us with sense, reason, and intellect has intended
use.”
who has endowed
us to forgo their
Galileo
Galileo was born in Pisa, Italy. Although he did not invent the telescope, he made many
improvements on the instrument and was the first to use it for astronomy. By studying the Moon
through the telescope, he made many drawings of the moon, and the four major satellites of
Jupiter are named in his honor. He also was the first to study sunspots. He accepted the
Copernican theory of heliocentricity but could not accept Kepler’s idea that the orbits of planets
were elliptical. His writings soon got him in trouble with the church and he was imprisoned for
heresy and spent the rest of his life under house arrest. Sir Isaac Newton was born the year he
died.
On the Shoulders of Giants
by Lloyd Flaig
Lethbridge Astronomy Society
Sir Isaac Newton 1642 – 1727
Isaac Newton once said, “If I have been able to see further, it was only
because I stood on the shoulder of giants.”
This distinguished physicist, mathematician, astronomer, alchemist, natural
philosopher and theologian was born in England. As an astronomer he is
credited with the concept of gravity, the three laws of motion, light, and
the idea of the reflecting telescope. Edmond Halley, a contemporary of Newton and one of his
strong supporters, used the three laws of motion to predict when the comet now named after him
would be seen again. The laws of motion are used in the hundreds of satellites and in space travel.
Newton’s influence on the history of science was demonstrated in 2005 in a survey at the Royal
Institute that chose Newton as more influential that Albert Einstein.
For more information on Sir Isaac Newton and the three laws of motion, look to the internet or
visit the Lethbridge Astronomy Society.
21.
Autumn Equinox
The September Equinox
Gord Falconer
http://www.lethbridgeastronomysociety.ca/
The Earth rotates once a day on its axis, and revolves
once a year around the Sun. But the axis is tilted 23 ½
degrees to the plane of the orbit around the Sun - which
is why globes have that strange tilt!
Usually, one end of the axis is tilted toward or away from the Sun; but twice each year, at the time
of the equinox, (from Latin – “equal night”), the axis is aligned so that neither end is pointed
toward or away from the Sun. At such times, the Sun is directly over the equator, and it rises and
sets exactly in the East or West, no matter where you are on the Earth, apart from the North Pole
and South Pole.
This year, the September Equinox occurred at 3:18 p.m. (MDT) on Tuesday, Sept. 22. Now that we
have passed the equinox, the Sun rises to the South of due East, and sets to the South of Due
West. We are accustomed to calling this the “autumnal equinox”, because it marks the official
beginning of autumn. But we should remember that around 20% of the world’s population lives in
the Southern Hemisphere, where the seasons are inverted; for them, this occasion marks the
beginning of Spring. So, we ought to try to adopt a less “north-Centric” term – the September
Equinox.
http://www.glyphweb.com/esky/concepts/equinox.html
http://www.asc-csa.gc.ca/eng/educators/resources/astronomy/multimedia/module3/reasons_seasons/reasons_seasons.swf
22
The Harvest Moon
By Gord Falconer
Lethbridge Astronomy Society
Because the Moon goes around the Earth, it is constantly
moving against the background stars. So, even though a
star will rise at almost the same time, (actually, 4 minutes earlier), on 2 successive nights, the
Moon has fallen behind, and will rise, on average, 50 minutes later each night. However, this 50minute figure is just an average; there is a lot of variability over the course of a lunar month. From
the latitude of Lethbridge, the difference between one night and the next can be as little as 18
minutes, or as much as 90 minutes.
Each year around the time of the September Equinox, the Full Moon occurs just when the day-today variation is at a minimum. So, for several evenings the Full or nearly-full Moon rises not long
after sunset, enabling farmers to work on the harvest by moonlight. Hence, the Full Moon closest
to the September Equinox has, for centuries, been known in folklore as the Harvest Moon. This
year, the Harvest Moon occurs on Oct. 4th. Consider taking a drive out into the country to watch
the moon rise!
For more information¨ http://www.lethbridgeastronomysociety.ca/
23
EARTH’S ATMOSPHERE
By Klaus Jericho
Lethbridge Astronomy Society
http://www.lethbridgeastronomysociety.ca/
The Earth’s atmosphere is unique in the solar
system, in its abundance of oxygen and water vapor.
It is composed of 78% Nitrogen, 21% Oxygen, and 1%
all others – mostly water vapor, with a bit of carbon
dioxide and other gases. This composition is due to
several factors, including our orbital distance from the sun; plate tectonics; volcanism that drives a
carbon/silicate cycle; and a stratified atmosphere.
The principal source of energy for the atmosphere is the Sun. The average flux of solar energy
arriving at the outer atmosphere of Earth is 1370 Watts/m 2. Some of the solar energy which
penetrates the atmosphere is absorbed, heating up the Earth. Much of the solar energy is
reflected back upwards by clouds, snow, ice, and sand; or it is re-radiated upwards as infrared
radiation. Greenhouse gases, notably water vapor, carbon dioxide and methane, capture much of
the infrared radiation, and re-radiate it back down to the Earth. Without this heat-trapping process
the Earth would on average be about 360 colder.
Several layers are recognized in the atmosphere; they vary in composition and temperature, as
well as pressure. The Troposphere reaches up about 12 km, and is where almost all of our “air” –
molecular oxygen and nitrogen – and our weather are found. The Stratosphere, extending up to
about 50 km, is rich in ozone (O3). The Mesosphere (to 85 km), gets colder as we go higher, is
relatively unknown – too high for jet aircraft or balloons, and too low for satellites. The extremely
thin Exosphere (which contains a relatively hot layer – the Thermosphere) - reaches several
hundred km higher; at its outer margins, it merges into the nearly perfect vacuum of space. The
space station travels in this thermosphere at 278 - 460 km altitude. TV satellites orbit once a day
about 36,000 km above the Earth.
Cool Website: http://earthguide.ucsd.edu/earthguide/diagrams/atmosphere
24
Celestial Fireworks
By Rena Woss
Lethbridge Astronomy Society
Who hasn’t felt the magic of a shooting star as it streaks
across the heavens lighting up the night sky? On any given
night you are bound to witness this event, but at certain
times of the year, you are in for a much bigger treat. The
Leonid meteor shower which occurs on the night of
November 17th is one such event. The best time to watch it is from 11 pm to 6 am. Peak activity is
predicted for 4:30 am (200 /hr) and 6 am (25-30 /hr). The meteors will appear to radiate from the
constellation Leo the Lion (can be located on the E-W path the Sun appears on). The reason for
this amazing event has to do with cosmic collisions. In its annual trek around the Sun, our planet
comes upon 9 major pockets of debris. You can think of it in terms of driving a car, coming upon a
sand storm. Whereas your windshield would get pelted with sand, Earth’s upper atmosphere gets
pelted in much the same way with left over comet rubble (most of which is no larger than the size
of a pea). What makes for the fiery display is the speed of the collisions. Earth travels through
space at 125,000 km/hr. The small bits of debris can travel even faster! So bundle up, put on the
hot chocolate and treat yourself to this wondrous cosmic event.
http://www.astronomy.com/asy/default.aspx?c=a&id=8525
http://www.skynews.ca/pages/10_best.html
25
December Sky Celebrations
By Rena Woss
Lethbridge Astronomy Society
Not only are we celebrating the holiday season this
month, the night sky holds much to celebrate as
well. There are 2 full moons in December (Dec. 2 nd
and 31st). When 2 fall in the same month, the
second is often referred to as a ‘Blue Moon’. If you
enjoy meteor showers mark December 13th on your calendar to take in the Geminid meteor
shower (constellation of Gemini). If the skies are clear we should see at least one meteor streaking
across the heavens every minute or two depending on how much light pollution there is in your
vicinity. We don’t have to worry about moonlight washing out the sky because the Moon will only
be a two-day-old crescent that sets early. On Dec. 20th the Moon and Jupiter will appear very close
together in the night sky making for a beautiful configuration. Take out your binoculars and look at
Jupiter – you should see 4 bright sharp points of light close to it. Those are Jupiter’s 4 giant moons
(Jupiter has 64 in all). Dec. 21 is officially the Winter solstice – the shortest day and longest night
of our year. After that the days start getting longer once again. No wonder people hold solstice
parties.
26
Valentine Rose
By Rena Woss
Lethbridge Astronomy Society
This beautiful image taken by NASA's Spitzer Space Telescope was
released a few years ago for Valentine’s Day. We refer to it as the
Rosebud of the Heavens as well as NGC 7129. Its redness is due to the
instrument by which the image was taken - an infrared camera
sensitive to invisible infrared light at wavelengths that are about ten
times longer than visible light. The Rosebud, like all star making clouds, is a massive region of gas
and dust where stars are born. This exquisite nebula is visible because close to 130 bright young
stars within it have recently ignited into life and are fluorescing the cloud. It’s located 3300 lightyears from earth in the northern constellation of Cepheus (the King). To find out more about the
birth of starts visit the Lethbridge Astronomy Society.
Image Credit: Spitzer Space Telescope NASA
27 March 5, 2010
POPSON PARK – GATEWAY TO THE STARS
by Rena Woss
Lethbridge Astronomy Society
The night sky is an inspiration to all of us, particularly
when we can see it! What gets in the way can be
cloudy nights, a bright full moon or worse of all –
LIGHT POLLUTION. Artificial lights create glow and
glare making it virtually impossible to see the stars
and connect with the awe and wonder of the heavens. March is a great month to view Saturn one of the most inspiring of all the planets. One of the best places to actually see it is at Popson
Park - home of the Lethbridge Astronomy Society and Oldman River Observatory. The park
provides one of the few public refuges from light pollution where a natural dark night sky can be
enjoyed. Saturday, March 27th is public viewing night. Mark it on your calendar and come down.
We begin at 7:30 with a short presentation. Sun sets at 7:55 and shortly thereafter we will take a
look at this magnificent planet through one of our many telescopes. Another important date to
mark is Thursday, March 18th. A symposium on light pollution is being held at the Lethbridge
Community College from 6 – 9 pm in the Instructional Bldg. (IB 1101). During the event you will
hear presentations, see displays and get the information you need to appreciate the concerns we
have about light pollution. Besides astronomy, these include issues of safety, health, environment,
energy waste, monetary waste and more. Fortunately, light pollution is one of the easiest forms of
pollution to control and correct. Our City is doing their part with newly designed flat lens lighting.
Come out and find out how we can make a difference.
http://www.lethbridgeastronomysociety.ca/
#28
Mar 19, 2010
Planetary Atmospheres and the Goldilocks Effect
By Klaus Jericho
Lethbridge Astronomy Society
The atoms or molecules of gas in our atmosphere, as in
other planets which have atmospheres, are whizzing
around at hundreds of meters, or even a few kilometres,
every second. Lighter particles move faster than heavier
ones, and hotter gases move more quickly than colder
ones. Each planet has its own escape velocity; an object
moving faster than the escape velocity will overcome the planet’s gravity, and fly off into space.
The escape velocity depends on a planet’s radius, and its mass. Earth’s escape velocity is about 11
km/s.
Now let’s consider 3 planets in our solar system. Mercury is not very massive, and it is very hot –
about 4300 C at its surface. The combined effect of its low escape velocity and high temperature
means that any particles of gas, even heavy ones, will fly off, which is why Mercury has no
atmosphere at all.
At the other extreme, Jupiter is massive and cold. It has such a high escape velocity that even the
lightest gases, Hydrogen and Helium, are too cold and too slow to escape. Jupiter has enormous
quantities of these and other gases, in its atmosphere (and in the body of the planet itself).
What about Earth? As in the story of Goldilocks, there is a happy medium – not too hot, not too
cold; not to heavy, not too light. The combination of atmospheric temperature and escape
velocity is such that lighter gases such as Hydrogen and Helium will escape into space; but heavier
gases, such as Oxygen, Nitrogen, Carbon Dioxide, and Water Vapour, remain trapped in our
atmosphere. Aren’t we lucky!
#29
SATURN AND ITS RINGS
Lethbridge Astronomy Society
By Gord Falconer
Galileo’s crude telescopes did not allow him to clearly see
Saturn’s rings. His earliest sketches (1610) showed lumpy earlike projections on each side of the round body of the planet. A
few years later, he was baffled when these lumps had completely
disappeared!
By the mid-1600’s, this mystery was solved; better telescopes revealed that Saturn was
surrounded by a very broad, but extremely thin, ring. How thin? If you wanted to use ordinary
photocopy paper to make a model with the right proportions, you’d need to cut out a circle 28
meters in diameter!
At times the rings are fairly open towards us, and can be easily seen. But as Saturn orbits the Sun
each 29 ½ years, the angle between Earth, Sun and Saturn changes. At two opposite points in the
orbit, the rings are edge-on, and they disappear completely from sight. As Saturn continues on its
orbit, the rings gradually open up again to a maximum, and then slowly get thinner again.
The rings are big and bright; when they are “edge-on” or nearly so, Saturn is noticeably fainter
than when the rings are open wide. You can duplicate this effect easily by holding an ordinary CD
edge-on to your view, then tilting it – see how much brighter it looks?
Saturn has just passed through one of these edge-on times, and the rings are slowly opening. If
you are patient, you can watch Saturn gradually brighten over the next several years. In March,
Saturn is near the tail of Leo the Lion, low in the east as it gets dark. On the evening of March 29, it
will be close – about the width of your fist at arm’s length – to the nearly full Moon.
http://www.lethbridgeastronomysociety.ca/
#30
HOW BIG IS THE SUN?
May 20, 2010
By Gord Falconer
Lethbridge Astronomy Society
Our star, the Sun is Really, Really, BIG!
Its diameter is 108 times that of the Earth. Cube that
number, and you’ll see that the volume of the Sun is
over one million times that of our little planet. In
other words, if the Sun were hollow (it isn’t), over a
million Earths would fit inside.
What about mass? Here’s a visual experiment that’s
easy, quick, and makes the point. You need 10,000 identical “things” – so they need to be small.
Hmmm….. Grains of sand? Too messy. Pennies? Ten thousand of them? Really heavy….
Unpopped popcorn kernels? Perfect! Small; not messy; 10,000 will fill a 4-liter ice cream pail about
2/3 full.
Now here’s the demonstration: Imagine that the 10,000 kernels represents the mass of the entire
Solar System: 1 star, eight planets (sorry, Pluto); 160 or so moons; tens of thousands of asteroids;
countless meteors, comets and dust. Now divide the popcorn kernels into 2 piles, one for the Sun,
and one for everything else. Tedious, you say? No – you need only scoop out 13 – that’s right, 13
– kernels. Eight for Jupiter; 3 for Saturn; and 2 for everything else. To put it in math terms: The
Sun comprises 99.87% of the mass of the Solar System!
Photo Credit: NASA
#31
June 6TH 2010
Figuring out the age of the Sun
By Gord Falconer
Lethbridge Astronomy Society
A serious problem in late-19th century science related to the Age of
the Sun. Geologists and Physicists were completely at odds. Here’s
why:
By the middle of the 19th century, scientists knew the Sun’s mass, and its energy output. At that
time, the most energetic process known to science was chemical combustion – e.g. the burning, or
even explosion, of gasoline, hydrogen or even dynamite. But even if you ignore the need for a
whole lot of oxygen, a Sun-sized mass of hydrocarbons burning at a rate sufficient to generate the
necessary energy output, would burn itself up, totally, in roughly 10,000 years.
As geology came into its own as a serious scientific discipline, the
apparent age of the Earth kept growing by leaps and bounds.
Once the geologists concluded that the mile-deep Grand Canyon
was cut, one grain of sand at a time, by the Colorado River, they
boldly proclaimed that the Earth must be millions (then tens, then
hundreds of millions…) of years old.
So what was the answer? E=mc-squared! Albert Einstein, in 1905,
realized that a very small amount of mass – and it didn’t matter whether it was plutonium or
peanut butter – could be converted, by thermonuclear fusion, into huge amounts of energy. The
Sun therefore has enough hydrogen fuel to have been “burning” for 5 billion years, and to keep on
doing so for 5 billion more.
To learn more about our universe: http://www.lethbridgeastronomysociety.ca/
#32
Umbra Fever
By Gord Falconer
Lethbridge Astronomy Society
Some years ago, an avid eclipse-chaser coined the expression, at once
both witty and profound, “Umbra Fever”. It describes an incurable
compulsion to ruin an otherwise perfectly fine sunny day by travelling,
regardless of distance or cost, in order to stand in the Moon’s shadow,
thereby blocking out the Sun altogether!
Total solar eclipses occur every 18 months or so, but only over a very
narrow band on the Earth’s surface. Sometimes, they pass over
populated areas, but they are just as likely to occur near the poles or
over deserts or oceans. From any given location on Earth, a total eclipse is visible, on average,
only once every 350-400 years. So – to see a total solar eclipse during your lifetime, you must be
(a) lucky; (b) very patient; or (c) prepared to travel.
This writer has had incurable umbra fever since 1970. So far I have sought relief in Nova Scotia;
Manitoba; Mexico; Curacao; France; Zambia; Libya; China; and the East China Sea. Still no cure yet;
so on July 11 I will be on Hikueru Atoll in the Pacific Ocean, hoping for a clear sky.
What about Lethbridge? There will be one fairly close by (Idaho) on Aug. 21, 2017. But if you are
determined not to leave town, better start exercising and eating well; the next total solar eclipse
here isn’t until Aug. 23, 2044.
Photo: Murray Paulson
#33
Perseid Meteor Shower
- a Night of Shooting Stars
By Rena Woss
Lethbridge Astronomy Society
For those who like staying up late or are on holidays,
the late hours of Thursday August 12th should prove to
be very special IF the skies are clear. On this and the
following night is the Perseid Meteor shower – a night
where we should be able to see approximately 60
meteors per hour lighting up the sky as they streak
across it. Because the new moon falls on Aug. 9th, there will be no moonlight to wash out the sky
so the meteors will appear brighter than ever.
Best time for viewing is an hour or so before midnight when the constellation of Perseus is well
positioned for greatest visibility. The Perseid Meteor shower is named for the constellation
Perseus which is where the meteors will appear to radiate from. All you need to enjoy the event is
to step outside –turn off your yard lights and get yourself a comfortable chair. This event is one of
summer’s celestial highlights.
To learn more about our universe: http://www.lethbridgeastronomysociety.ca/
For more on the meteor shower: http://www.amsmeteors.org/showers.html
#34.
Oct. 2010
Star Light, Star Bright
By Marianne Durocher
Lethbridge Astronomy Society
One of the biggest problems that amateur
astronomers face when gazing towards the heavens
isn’t that our telescopes are too small, or the weather
is unfavourable for viewing, its pollution. Yes, that all
too familiar word. But this particular kind of pollution,
known as “light pollution,” is the easiest form of
pollution to not only clean up but also to avoid all
together. The source of light pollution comes from porch lights that shine into your neighbour’s
backyard, billboards that point their spot lights up into the night sky, and even street lamps that
aren’t properly equipped with domes that direct light down toward the street, where it belongs.
Fortunately for citizens of Lethbridge, City council has recently passed a motion to designate the
Oldman River Observatory, home of the Lethbridge Astronomy Society in Popson Park as an
“Urban Sky Park.” What does this mean? It means we now have a place within the city where we
can go to gaze up into the night sky to view the moon, the stars, the planets, or to ponder the
universe’s beginning or end and do so under a natural night sky.
#34
Published Nov.
26th/10
Star Gazing in November
By Rena Woss
Lethbridge Astronomy Society
Daylight savings means early evenings and with that,
opportunity to enjoy the night sky at a reasonable hour. One
object you will notice immediately is in the southwest part of
the sky. The brilliant star-like object high in the heavens is the
king of planets – Jupiter. If you own binoculars, get them out and take a look. You will notice 4
bright points of light strung out alongside Jupiter. Those lights are Jupiter’s largest moons -Io,
Ganymede, Callisto and Europa. In all, Jupiter has 63 confirmed moons. Imagine if Earth had that
many! To learn more about the universe visit the Lethbridge Astronomy Society and the Oldman
River Observatory. Public viewing is held the last Saturday of each month beginning at 7:30. We
are located in Popson Park, south of the University. The area provides a natural dark night sky
which is protected by the City of Lethbridge from light pollution. More on that good news in
another column.
DEC.14, 2010
Light Pollution is a Problem
Easily Fixed
By Rena Woss
Lethbridge Astronomy Society
December skies are bejeweled with stars
and planets. Step outside early in the
evening and you will see Jupiter - the titan
of the planets shining brightly in the
southeast. In the morning take another
look in the same direction. Jupiter will
have set many hours earlier and in its place you will see brilliant Venus heralding the rising Sun.
Venus is often called the ‘morning star’. Its brightness has to do with the thick dense clouds of
sulfuric acid that surround it and which reflect approx. 70 per cent of the sunlight that hits it back
into space. Yes, being able to see stars and planets and knowing something about what you see is
very inspiring! Unfortunately for most city dwellers it’s only the brightest of heaven’s objects like
Jupiter and Venus that we can actually see. The problem of course is artificial lighting. Light
pollution is a problem generations before us never had to worry about. People were able to
connect with the splendor of the heavens simply by stepping outdoors and looking up.
Today - in order to really experience a ‘natural’ dark night sky generally means travelling out of the
city somewhere. This is a sad statement for our society. Not being able to see the night sky in its
natural state cuts us off from an important aspect of nature and our common heritage.
Fortunately for people living in Lethbridge, we now have a place within the city limits where the
night sky is sheltered from artificial lights. Back in September of this year, Lethbridge City Council
passed a motion to protect the skies around the Oldman River Observatory from light pollution.
This is good news for all of us because Lethbridge now has a reliable site for people to access and
enjoy a natural night sky without interference of artificial lighting hampering the view. This is also
good news for the wildlife in the surrounding area, particularly the nocturnal creatures that
depend on the dark. The initiative undertaken by the astronomy society and City of Lethbridge is a
first in Canada and the culmination of an effort that was launched during International Year of
Astronomy. The Lethbridge Astronomy Society is open to the public the last Saturday of each
month for public viewing and open for bookings throughout the year from September to April. The
Make a point of coming down to connect with YOUR universe. Our next public viewing is January
29th beginning at 7:30.
http://nineplanets.org/venus.html
2011
Dark Sky Preserves
By Rena Woss
Lethbridge Astronomy Society
On March 26th, 2011, Jasper National Park was named a ‘Dark Sky Preserve’. This is Canada’s 13 th
dark sky preserve and with 11,228 square kilometers set aside, it is also the largest.
For those not familiar
with the term, a ‘dark
sky preserve’ it is an
area in which artificial
light is eliminated or
controlled so that a
natural night sky may
be experienced. Not
even a hundred years
ago, this was the norm
rather than the
exception. Today, we
are the first people in
history to be cut off
from the splendor of
the night sky and with
that a vital part of our
human heritage. To see the night sky in its natural state allows us to connect with the splendor of
the universe - something next to impossible when living in a city bathed in artificial light.
The problem of light pollution goes well beyond seeing the night sky. Artificial light impacts the
Environment, all the creatures that depend on darkness, it affects circadian rhythms, human
health, safety and beyond. The good news is that light pollution is about the easiest form of
pollution to control and correct. It’s all about choosing light fixtures that are designed to direct the
light to shine down rather than across (i.e. onto a highway or your neighbor’s yard) or up into the
night sky, and it’s about regulating how often lights are turned on and off. For more information
on this important subject you can down load a Light Pollution Power Point presentation off our
website. With summer around the corner and holiday and camping trips being planned, a trip to a
dark sky location or preserve will help you get reacquainted with the marvels of the night sky.
Besides Jasper Provincial Park, Cypress Hills Interprovincial Park (just out of Medicine Hat) is
another location where skies are protected from light pollution. Within Lethbridge city limits, the
Lethbridge Astronomy Society (located in Popson Park) has recently been given protection from
artificial lights (September 2010). In the not too distant future, we are hoping the entire park will
be protected. If this should happen, Lethbridge will be the first city in Canada to have an ‘urban
star park’. This great news will benefit us all and will ensure that the Lethbridge Astronomy Society
is able to carry out its work for many more years to come.
http://www.rasc.ca/news/Jasper_National_Park_Canada_Designated_Dark_Sky_Preserve.shtml