Volume 6, Issue 3

The Sunset Gaze t te Serving the Tri -Cit ies s ince 1975

Sunset Astronomical Society

Meeting information

Meetings are generally in the theater in the Delta College Planetarium in Bay City. The meetings will usually be on the 2nd Friday of each month at 7:00 PM. Watch the newsletter for changes in dates and times. Membership is not required to participate in meetings and activities. See Page 6 for this month’s meeting site.

Membership Information

Student / Senior: (17 years & younger, 65+ years)

1 year - $15

2 year - $20

Regular: (18+ years)

1 year - $20

2 year - $30

Family: 1 year - $25

2 year - $40

New Members receive a New Member Observing Kit at their first meeting, courtesy of SAS. Membership includes voting privileges, the newsletter and free admission into Delta College Planetar-ium shows.

Subscription Information

Subscription prices available at club rate with the purchase of individual or family membership.

“Sky and Telescope” Magazine: 1 year - $32.95 + Membership

2 year - $65.90

“Astronomy” Magazine:

1 year - $34.00 + Membership

2 year - $60.00 + Membership

November, 2008

“Solar System Safari Night”

Special Event at the

Delta Planetarium Bay City

Friday, 21st November

6:30 - 7:00 Registration and lobby activities

7:00 - 8:00 “Solar System Safari” in Plane tarium Theater

8:00 - Desert

- Lobby displays of telescope, information etc

- Observing on Observation Deck / Sidewalk (weather permitting)

Registration for the public: $8.00, Adults

$6.00, Seniors / Children

Please register in advance by calling 989-667-2260

Reminder to all SAS and AU members: Bring

in your telescopes and observing gear!

PAGE 2 THE SUNSET GAZETTE VOLUME 6 , I SSUE 3

More Impressions from the

Great Lake Star Gaze 6

Above: Vendor’s tent with some beautiful hand

crafted wooden observing chairs and eyepiece

boxes.

Above right: Michael Foerster giving his key

note “Are We Alone?”, a very fitting theme to

the ongoing saga in this newsletter (see page

4/5).

Left: A group photo of my tent neighbors, the

Ford Amateur Astronomy Club.

Below left: Michael Bakich giving a talk about

the history and naming of the constellations.

PAGE 3 THE SUNSET GAZETTE VOLUME 6 , I SSUE 3

Michael Foerster and Michael Bakich

putting their signature onto the SAS

banner.

Left and right : Lucky winners of one

the kids and door prices!

(Relative) Early Saturday morning im-

pression of the GLSG6 !

By Martin Grasmann. This is the seventh part of an extended summary of a lecture about Astrobiology that Dana Bachmann, SETI Institute/SOFIA-Ames gave on Wednesday, March 26th at the CMU.

We have reached the Saturn system and are closing in onto the large moon Ti-tan, a featureless orange-yellow sphere surrounded by a dense atmosphere. It is the January 14th, 2005 when suddenly a fiery violet trail is rapidly crossing the at-mosphere - a meteor? No, it is a man-made object, the European landing probe Huygens just recently released from the NASA space probe Cassini which is explor-ing the Saturn system since 2004. Huygens just entered the atmosphere of Titan

with 5 km/sec and is now rapidly de-celerated. A heat shield protects the probe from the 1100 C heat gener-ated by the thermal friction with the dense atmosphere. 5 minutes later a small detonation ejects a small parachute which removes the upper heat shield, thus a large parachute can then be deployed and decelerates the probe further. Now all instruments are exposed and start to work: three cameras mounted 120 degrees apart trying to gaze to the thick haze. A whole battery of ana-lytical instruments is investigat-ing the chemical composition of the atmosphere. Then another

bang and the large parachute is replaced by a smaller one: the probe will now descend over ca 2 hours until it reaches the surface of Titan. At that point in time it was still not clear if Huygens was to touch down on solid ground or splash into some sort of hydrocarbon sea. Only below a height of 60 km some shadowy features of Titan’s surface become apparent: first only dark

and bright patches are visible, but at about 20 km over ground the view suddenly clears. Huygens now seems to fly over a strange but somehow familiar landscape: small narrow valleys are visible which are only a few 100 m wide but several km in length. The pic-tures show pale hills with dark "rivers" run-ning down to a dark plain. Current understanding is that the hills (also referred to as highlands) are composed mainly of water ice. Dark organic compounds, created in the upper atmosphere by the ultraviolet radiation of the Sun, rain from Titan's atmosphere. They are washed down the hills with the methane rain and are deposited on the plains over geological time scales. Wind gust are now carrying Huygens away from this region and finally the probe reaches the ground. The atmos-pheric pressure is 1500 mbar (1.5 times higher than on Earth sea level) but it is cold, very cold: -179 degree Celsius or -290 °F.

The air contains 90% nitrogen, a few percentage methane and other hydrocarbons like ethane. After landing, Huygens photographs a dark plain covered in small rocks and pebbles, which are composed of water ice. The surface is darker than originally expected, consisting of a mixture of water and hydrocarbon ice. It is believed that the "soil" visible in the images is precipitation from the hydrocarbon haze above.

Indeed the photos looked somewhat familiar to the first pictures taken by the space probe Viking 1 1976. After about an hour the radio contact to Cassini ceased which was now moving beyond the horizon of the landing site. Nonetheless powerful radio telescopes on Earth were still able to

receive weak signals from Huygens for 4 hours, only then the batteries run out of power and Huygens is silenced forever.

ARE WE ALONE? or

“The discovery of one-cell organisms on a distant planet in our solar system

or beyond would have an impact as big as the Copernicus revolution”

PAGE 4 THE SUNSET GAZETTE VOLUME 6 , I SSUE 3

Why Titan? Titan is the largest moon of Saturn and with a diameter of 5150 km larger than Mercury (4880 km) and the only moon in the solar system known to have a dense atmosphere. It also seems to be the only object other than Earth with clear evidence of stable bodies of surface liquid. Titan is the sixth moon from Saturn and frequently described as a planet-like moon because it is the second-largest moon in the Solar System, after Jupiter's moon Ganymede. Titan orbits Saturn once every 15 days and 22 hours. Like the Earth's moon and many of the other gas giant satellites, its orbital period matches its rotational period, because Titan is tidally locked in synchro-nous rotation with Saturn.

Titan was the first known moon of Saturn, and discovered in 1655 by the Dutch astronomer Christiaan Huygens, after which the Titan probe was named. Very early Titan grabbed the attention of astronomers. In the 1940s spectroscopic measurements detected larger amounts of methane which pointed to a relatively dense atmosphere. The Pioneer 11 space probe confirmed 1979 that Titan was sur-rounded by a dense, mainly nitrogen containing atmosphere which contained a 1.6% methane and trace amounts of other gases such as hydrocarbons (including ethane, diacetylene, methylacetylene, acetylene, propane, cyanoacetylene, hydrogen cyanide, carbon dioxide, car-bon monoxide, cyanogen). The vivid orange color as seen from space is probably produced by other more complex chemicals in small quantities, possibly tholins, tar-like organic precipitates. These hydrocarbons are forming in Titan's upper atmosphere when the Sun's ul-traviolet light breaks up methane, producing a thick orange smog. One intriguing fact is that energy from the Sun should have converted all traces of methane in Titan's atmosphere into hydrocarbons within 50 million years which is not long compared to the age of the solar system. This suggests that there must be reservoir of methane which replenishes the atmospheric methane all the time. This reservoir could be on or within Titan itself. Many astronomers have suggested that the ultimate origin for the methane in Titan's atmosphere is from within Titan itself, released via eruptions from cryovolcanoes. A possible biological origin for the methane has not been discounted either (see below).

The successors of Pioneer 11, Voyager 1 and 2 found surface tem-peratures of -180 C — conditions where methane can exist in liquid or gaseous form. But even the sharp cameras of Voyager 1 and 2 could not penetrate the thick atmosphere and so the structure of surface remained an enigma. At the begin of the 1990s it was discov-ered that Titan’s atmosphere was transparent in the near infrared and the new large earthbound telescopes with adaptive optics were able to obtain first rough maps of the surface of the moon where brighter and large dark regions were identified. The latter were thought to be oceans of methane but radar measurements from Earth did not reveal any larger amounts of liquid. Since 2004 the space probe Cassini is circling around Saturn in always changing orbits and one of its main targets is Titan. During a Cassini flyby in late February 2007, radar and camera observations revealed several large features in the north polar region that may be large expanses of liquid methane and/or ethane, including one sea with an area of over 100,000 km² (larger than Lake Superior). A flyby of Titan's southern polar regions in October 2007 revealed similar, though far smaller, lake-like features.

Scientists believe that the current atmosphere on Titan maybe similar to the atmosphere of early Earth and many hypotheses have been developed to bridge the step from chemical to biological evolution (see Miller-Urey experiment in the first part). Several experiments have shown that with an atmosphere similar to that of Titan and the addition of UV radiation, complex molecules and polymer substances like tholins can be generated.

There is enough organic material present on Titan to start a chemical evolution analogous to what have started life on Earth. Several theories suggest that liquid water (from an impact) necessary for the biological processes maybe preserved under a frozen insulation layer. Detection of microbial life on Titan would depend on its biogenic effects. As mentioned atmospheric methane and nitrogen could be of biological origin. Hydrogen has been cited as one molecule suitable to test for life on Titan: if methanogenic life is consuming atmos-pheric hydrogen in sufficient volume, it will have a measurable effect on the mixing ratio in the troposphere.

But there are formidable obstacles to life on Titan, and any analogy to Earth is not exact. At a vast distance from the Sun, Titan is frigid and its atmosphere lacks CO2 (a greenhouse gas). Thus while life itself may not exist (yet), the pre-biotic conditions of the Titan environ-ment, and the possible presence of organic chemistry, remain of great interest in understanding the early history of the terrestrial bio-sphere. Nonetheless conditions on Titan could become far more habitable in future as stellar evolution goes. Over the next few billion years the Sun becomes a red giant greatly expanding the habitable zone into the outer reaches of the solar system. Titan’s surface tem-peratures could rise to ~200K, high enough for stable oceans of water/ammonia mixture to exist on the surface. These conditions to-gether could create an environment agreeable to exotic forms of life, and will subsist for several hundred million years, long enough for at least primitive life to form.

Want to know more about the Moons of Saturn and the outer Solar System? Then watch this space! The next parts

of this gripping story of ‘Are We Alone?’ will follow in the next issues of the Sunset Gaze t te !

PAGE 5 THE SUNSET GAZETTE VOLUME 6 , I SSUE 3

Size comparison of Ligeia Mare with Lake Superior.

Martin Grasmann Secretary - SAS 6108 Summerset Drive Midland, MI 48640

SUNSET ASTRONOMICAL SOCIETY THE SUNSET GAZETTE SERVING THE TRI- CITIES SINCE 1975 http://sunsetastronomicalsociety.com

President, Bill Albe

billalbe@chartermi.net

1st Vice President, Steve VanTol

stevenv106@aol.com

Secretary, Newsletter Editor, Martin Grasmann

martin.grasmann@sbcglobal.net

UPCOMING MEETINGS

For start times see first page!

“Solar System Safari Night”

Special Event at the

Delta Planetarium Bay City

Bring your telescopes and observa-tion equipment for display to the public in the Planetarium lobby!

If weather permits there will be observing on the up-per deck or on the sidewalk.

Observable Planets:

Venus and Jupiter shines low in the southwest at dusk. Saturn after 3 am.

December 12: Planetarium Show. To be announced

January 9: Bill Albe "Experience a Solar Eclipse in South America"

February 13: Telescope Workshop: "How to Use the Telescope You Got for Christmas" including "Collimate and Use Your Telescope"

March 13: Messier Marathon prepara-tion.

April 10: "Astronomical Tutorial" / NASA Lunar Sample training

SAS Elections

April 17: Star Party at Tawas: weekend of 17-19 (Fri - Sunday)

April 24: Messier Marathon with the AU

May 8: “The Lunar Landings” Dick Van Effen

May 1 - 31: Possible Star Party at the 30” Observatory of Garry Beckstrom. Weather permitting on short notice.

If you are interested in presenting to our club, please contact Bill Albe:

(989) 835-4142

Nov 13: Full Moon

Nov 17: Venus is very close (5’ to 8’) be-

low 2.8 mag Lamda Sagittarii at dusk: Re-

markable sight in binoculars and telescopes!

Nov 19: Last quarter Moon

Nov 21: Crescent moon ca 5° to the right

of Saturn.

Nov 22: Venus is shines 1° to upper right

of 2.1 mag Sigma Sagittarii at dusk.

Nov 27: New Moon.

Nov 30 - Dec 1: Jupiter is just 2° from

Venus. The crescent moon ca 8° to the

planets lower right on Nov 30 and 3 to 4°

to thir upper left on Dec 1.

Late Oct to anywhere in Nov: Taurid

meteor shower: bright brilliant slow moving

meteors up to 3 to 5 per hour when the

showers radiant is near the Pleiades high in

the sky satring late in the evening

Dec 10 - 11: Moon occultes Pleiades over

North America: starts 2:30 am to 3:00 am.

Telescope needed!

UPCOMING EVENTS SAS Meeting

November 21, 2008

Delta College Planetarium Theater