|
This is the Classical Astronomy Update, an email newsletter especially
for Christian homeschool families (though everyone is welcome!)
Please feel free to share this with any interested friends.
IN THIS UPDATE:
- Anouncements
- Dance of the Planets
- Observe the Retrograde Motion of Mars
Then Paul stood in the midst of Mars' hill, and said, Ye men of Athens,
I perceive that in all things ye are too superstitious. For as I passed
by, and beheld your devotions, I found an altar with this inscription,
TO THE UNKNOWN GOD. Whom therefore ye ignorantly
worship, him declare I unto you. - Acts 17:22-23
Welcome to the Classical Astronomy Update!
Hello Friends,
Clear skies permitting, November can be a great time to observe the night sky. Now that the clocks have "fallen back," it is fully dark early in the evening, as early as 6:00 PM, depending on your location. Unlike the summertime, you can observe the stars for many hours before bedtime.
The Summer Triangle is high overhead as night falls, as shown on page 128 of our Signs & Seasons homeschool astronomy curriculum. The Summer Triangle is not a constellation, but as "asterism" formed of the three bright stars Vega, Deneb and Altair. Though it is a summer star pattern, the Summer Triangle is still visible in the evening sky since the shortening of the daylight offsets the regular seasonal advance of the constellations. The Summer Triangle points south, and the bright planet Jupiter is to the east (i.e., the left) of the general direction in which the Summer Triangle is pointing.
By 9:00 PM, only a few hours later, the "Great Square" of the constellation Pegasus is high in the sky, as shown on page 129 of Signs & Seasons. Also, at this same hour, the bright stars Vega and Capella are "balanced" in the northern sky, around the North Star Polaris, as shown on page 141 of Signs & Seasons
. In this way, we can the summer constellations around Vega can be seen sinking into the west, as the winter constellations near Capella rise in the east. For those who know the constellations, this is a sure seasonal sign of fall in the night sky.
In another couple hours after that, the magnificent constellation Orion is seen rising in the east. The Pleiades star cluster shines high in the eastern sky. Autumn can be a great time to begin learning the constellations, and the Signs & Seasons curriculum can help you and your family learn the seasonal signposts.
Announcements
Night of the Earlybirds
Are you an earlybird or a night owl? All my life, I have been a night owl, like many other astronomy enthusiasts. I can stay up late as I like, until I'm ready to turn in. But on the other hand, it can be very hard to wake up early in the morning. Sunrises are a very rare and precious thing in my life since I'm rarely up to see them, especially in the summer, when the rises around 5:30 AM.
Though I'm not one myself, I've known plenty of earlybirds in my life. These are the people that do three loads of laundry and the entire crossword puzzle before arriving at work at 6:30 AM. However, these types get sleepy after dinner and are dozing off by 10:00 PM. I sometimes wish I could be that way myself, because it is true that "The earlybird gets the worm." But I'm just not, and that's that. There was one time when this night owl actually flew with the earlybirds....
One night, about 15 years ago, I woke up with a start at 5:00AM in total darkness. It was the first night in over a year that our first baby slept through the night. He usually woke me up about 10 times each night, but this time he didn't. I was startled upon awakening, afraid I'd find a problem with the baby. Well, the kid was just fine, but I was shocked totally awake and decided to just go to work early.
On the bus, riding along in pitch blackness, there were all these chatty people. They were visiting and laughing and having a grand old time. I thought to myself, "what is up with these people?" Normally, I can't speak in a civil manner to other humans before I've had several cups of coffee. I couldn't understand how these people could be so alert and cheerful so early in the morning. So I finally made it off the noisy bus to the donut shop looking for a morning sugar jolt. Same story there. There was a whole table full of chatty people sitting in the donut shop, laughing and having a great time.
I was so relieved to walk out into the relative quiet of the city street. Puzzled, I looked up at the half-moon shining in the black sky and thought, what's up with these people? How can anyone be so happy and lively and chatty and awake at 6 in the morning? Where were all the grumpy people like the regulars I saw on my usual bus ride?
Then it occurred to me -- this is the hour of the earlybirds! Every day at this time, all the night owls like me are more than an hour away from dragging it out the door. Meanwhile, unseen by our groggy eyes, the earlybirds are having a wide-awake, early morning cheerful party. Anyway, that was the one day of my life when I got to observe the earlybirds in their natural habitat!
If you're an earlybird yourself, and are regularly up before sunrise, you have a great opportunity to observe the morning constellations and the waning phases of the Moon. You can learn more about that in our Signs & Seasons curriculum. You earlybirds have a special opportunity to observe the motion of the planet Mars in the coming season.
Dance of the Planets
Observe the Retrograde Motion of Mars
At any given time, the planet Mars is an inconspicuous celestial object, undistinct from the background stars except for a very distinct ruddy orange color. However, once every two years, faint Mars blazes forth into brilliance, approaching or even surpassing Jupiter in brightness. In late 2009, we are entering another season of Mars's brightening, as Mars approaches opposition on the evening of January 29, 2010.
At opposition, a planet is opposite the Sun in the night sky. Therefore, the planet rises in the evening as the Sun sets. The Earth lies between the planet and the Sun at opposition, and the planets are at their closest positions to each other. The superior planets Jupiter and Saturn have regular oppositions each year, but Mars moves more swiftly, and the Earth requires more time to "catch up" to Mars in its orbit. Therefore, oppositions of Mars occur in roughly every two years and a month.
As opposition approaches and the Earth moves into alignment, the planet appears to move backwards through the zodiac constellations. This is the retrograde motion of the superior planets. As explained on page 155 of Signs & Seasons, the retrograde motion is an optical illusion created by the changing line of sight between the planet and the background stars, as the Earth begins to overtake the planet.
Throughout history, since ancient times, the retrograde motion of the outer planets was a total mystery. There was no natual explanation for this phenomenon according to the geocentric cosmology of the ancient world. The ancient pagan Greek philosophers such as Plato concluded that the planets had souls, since their motion seemed to be a deliberate product of free will.
As astrology became popular in the Greek and Roman world, the planets became associated with gods, and shined down cosmic influences on the world. In medieval times, as one can read in Dante, the planets were thought to be angels, or at least moved by angels. With the advent of the heliocentric cosmology, it was finally shown that the retrograde motion was a natural phenomenon resulting from the motion of the Earth. Science has confirmed the shown that the planets are neither gods nor angels, just lifeless bodies careening through space under their own momentum.
Mars in 2009 and 2010
The current apparition of Mars is an excellent opportunity to observe the retrograde motion, since Mars will pass near some of the brightest stars in the night sky. This month, November, 2009, Mars is drawing away from the constellation Gemini and its bright twin stars Castor and Pollux. Mars was aligned with these stars on October 13, and will return again to this part of the sky in March, 2010.
Mars will continue moving east through the constellations this fall, passing through the faint stars of the constellation Cancer the Crab. The eastward motion of Mars will then slow down, and Mars will be stationary on December 21, the first day of winter for observers in the northern hemisphere. At this time, Mars will be near the constellation Leo, not far from the bright star Regulus.
After this station, Mars will move backwards through the constellations, toward the west. Mars reaches opposition on January 29, part way through its retrogradation. At this time, Mars will be at its closest to the Earth, and blazing at full brightness. Mars will appear to have a distinct copper color, like a new penny. After opposition, Mars will be visible the entire night. Until then, Mars rises in the evening sometime after sunset, and will rise earlier and earlier over the coming months.
Currently, Mars is rising about 11:00 PM, enabling night owls to see Mars low in the northeast late at night. However, earlybirds can see Mars high in the sky over the south before sunrise, shining brightly in between Gemini and Leo.
Mars passes by the famous Beehive Cluster in Cancer on February 2, 2010. This will be a pretty sight through binoculars or a small telescope. Mars continues moving backwards toward the west throughout the winter, and reaches its station on March 11, 2010, again near the stars Castor and Pollux in Gemini. The retrogradation ends at this time, after which Mars resumes its normal eastward motion. Mars will again pass through the Beehive Cluster on April 20, 2010. On June 6, Mars will be in close conjunction with the bright star Regulus.
Each month, the Moon will swing by Mars in its monthly cycle. This month, the Moon will be nearest to Mars on the morning of Monday, November 9. If you're an earlybird, be sure to look up and notice this monthly pairing of Mars and the Moon. We'll plan on mentioning these conjunctions in this newsletter throughout the current season of Mars.
Also, be sure to notice Mars this winter, to be prepared for the annual "Mars Spectacular" email urban legend that makes the rounds each summer. Since Mars will be at its closest to the Earth in January, there's no way it can be closest again in August, since Mars has a two year cycle. So be sure to tell your friends in advance and let's get the word out early!
Coming in future Classical Astronomy Updates:
- The bright morning star Venus will be sinking toward the sunset through the fall, and will again be visible as as evening star in early 2010.
Til next time, God bless and clear skies!
-jay
The Ryan Family
Cleveland, Ohio, USA
When I consider thy heavens, the work of thy fingers, the moon and
the stars, which thou hast ordained, what is man that thou art
mindful of him? and the son of man, that thou visitest him?
- Psalm 8:3,4, a Psalm of David
If you would like to subscribe to the Classical Astronomy Update,
|
