Contributing Editor, Dan Matlaga: Astronomy Event 4/13 And Other Cool Stuff!

Welcome back Contributing Editor, Dan Matlaga!  You may recall from  Dan's first post that in addition to his degrees in Astronomy and Geology, Dan recently retired from a 36 year career teaching Astronomy at Arizona State University via their planetarium - which was very interactive and "hands-on" at the planetarium itself.  Dan will continue to educate us on the subject of astronomy, including keeping us informed on current "happenings in the sky", such as the event that begins tomorrow, Saturday, 4/13.

Of course, Dan was also one of Joe's closest friends from their teen years.

So now, here is Dan with not only the info. on the Saturday event, but several other cool treats as well.  Take it away, Dan...

Just last week on PBS, the Nova program was an excellent treatment of the Greek Antikythera machine. The machine, about the size of a laptop, was billed as the world’s first computer.  It was found as part of a shipwreck in 1901.  The mechanism is at least 2,000 years old. The encrusted gears remained as an interesting museum piece until the late 1950’s when an English physicist examined it and discovered it was capable of predicting the positions of the sun and moon on a kind of clock face.  

Clearly there were more gears to the device, so one could conclude the machine was capable of more than positions of the sun and moon.  The PBS show demonstrated how the mechanism was capable of illustrating the positions of the sun, moon and five naked eye planets.  It was capable of predicting lunar and solar eclipses as well. 

The history books dedicated to the path of western technology will have to be rewritten as a result of this machine!

                                      Watch Ancient Computer on PBS. See more from NOVA.

I recall David Van Pelt bringing up the subject of this machine early in the 1960's.  He'd read an article about it in an old issue of Scientific American.  Joe Egles and I listened intently, athough we were not as familiar with computers.  Our discussions on the subject centered on the classic Orrery, a geared model of the solar system on the ceiling in a circular room at the Hayden Planetarium in New York City.  We agreed if we ever made it to Athens, the Antikythera machine would be tops on our list. 

The three of us had a great respect for the sheer pleasure of knowing things.  Though I don’t ever recall a discussion on sports or the latest cars, our minds drifted through the fields of science and technology. If we three were together this Saturday evening, April 13^th, our thoughts would be skyward, specifically toward the west just after sunset.

Immediately after sunset, look above where the sun sets for the 12% illuminated crescent moon.  When the first stars appear, you will be able to find the bright “star” above the moon.  That is not a star but the planet Jupiter.  Between the moon and Jupiter, but slightly to the left, is the fainter red star Aldebaran, the eye of Taurus the Bull.  When it gets darker there will be an unmistakable letter “V” formed by dim stars.  The “V” represents the face of Taurus with Aldebaran forming the upper left part of the “V”.  A line drawn from Aldebaran through the moon, continued on the other side of the moon at a little more than the Aldebaran moon distance, is a faint group of seven stars known as the Pleiades. You can hold your thumb with extended arm up to the sky; your thumb will cover the Pleiades. 

How easy is it to locate these objects? The moon and Jupiter should be easy.  Aldebaran is fainter than the moon and Jupiter, but the close proximity of the moon and Jupiter should pose no problem provided the sky is dark enough and you have a clear western horizon, uninterrupted by trees or houses.  Chances are you may be able to locate only five or so Pleiades due to their low altitude. It helps if your local sky is reasonably dark and you are experiencing low humidity.  Just a few weeks ago here in Tempe, Arizona the humidity was 2%, with an increase of 3% after sunset. If you can find these objects, the stage is set.

Various Sky Viewing Conditions

The Pleiades are called the Seven Sisters.  To some Greeks they were known as the Seven Doves.  In our modern world, as well as millennia ago, the dove can be the symbol of the human spirit.  In an article for submission next winter, I’ll explain how the “V” in Taurus represents the physical.

So there you have it.  Early this Saturday evening the moon is between the symbols of the physical, the ”V” of Taurus the bull, and the spirit, the Pleiades. 

We learn in grade school the earth orbits the sun. The effect of this motion is to make the sun appear to travel two solar diameters across the sky each day in front of the far more distant stars.  Like the moon this Saturday, the Sun will appear to travel between the “V” of Taurus and the Pleiades.  In fact the position of the moon Saturday is about the same position the Sun will occupy on May 20th. 

A return to chaos occurs in classical mythology whenever a symbol disappears.  In this case the very bright sun forces the star symbols of the physical and spirit to disappear from our view; chaos between the physical and the spirit ensues.

How long will the chaos of physical and spirit last?  According to the Greek historian Hesiod in his “Works and Days", the Pleiades disappear from view forty days and nights.  This is an interesting number. Not only are there many references in the old and new testament of the number forty, we find it in relatively modern literature.  It is Ahab’s fortieth year at sea since becoming a boy harpooner that is described in Herman Melville’s Moby-Dick. The hunchback of Notre Dame brings the princess into the church, climbs up to the tower and shouts: “Sanctuary,” to the crowd below.  By declaring sanctuary the police cannot enter the church to rescue the princess for forty days.  We have the stories of Ali Baba and the Forty Thieves as well as the traditional period of quarantine lasting for forty days.

If you watch the Pleiades, you will notice with each passing evening they will appear lower and lower in the sky until they will no longer be visible on May 1^st.  They will reappear about June 9^th; when the Pleiades will emerge from the bright sunlight in the East, just before sunrise.

With so much riding on the observation of the Pleiades and other celestial bodies, is there any wonder why the Greeks would try to bring celestial observations down to earth to better predict the motions of the heavens in the Antikythera machine? 

You can stand out in the evening twilight over the next few weeks and watch as the Pleiades slide into the light of the sun and appreciate how this view inspired societies throughout time and place.

We have made great progress in representing the sky.  An excellent free download to your computer is the program Stellarium.  It is free and can recreate the skies from your backyard.  I hope to present more submissions that will be easier to follow if you have Stellarium on your computer.  It can create, among other things, this Saturday’s evening sky.

Here is a video about the Stellarium software.  Click on this link to download it for free!  http://www.stellarium.org/

Thank you so much, Dan - that was awesome!  Hope to see you again soon.  Can't wait to see what you have planned for us next.  We will download the  Stellarium software (I already have) and be ready to follow along!