Next Meeting: Friday, July 1, 2016
TAAA encourages the public to join our general meetings held on the first Friday of the month in the Steward Observatory Lecture Hall (Room N210) on the U of A Campus.
Location: U.S.G.S. Building, Room 253 (520 North Park Ave)
Contact: Dennis McMacken
An AFSIG article by Paul Trittenbach
Located 1.4 billion kilometers (9.6AU) from the Sun is the second largest planet and sixth planet of the solar system: Saturn. Its beautiful ring structure makes it the most popular planet among amateur astronomers and the public alike. Like Jupiter, Saturn is a gas giant planet composed predominantly of Hydrogen and Helium.
Saturn was the most distant planet known to the people of the ancient world. It was not viewed through a telescope before 1610 when Galileo Galilei turned his 30-x refractor upon it. To his amazement, he saw a pair of objects on each side of the planet, and sketched Saturn as a three-bodied world. After numerous observations, he sketched these lobes as handles attached to either side of the planet.
In 1659 the Dutch astronomer Christian Huygens, using a more powerful telescope than Galileo’s, proposed that Galileo’s handles were in fact a thin flat ring that surrounded the planet. Later in that century, in 1675, the Italian born astronomer Jean-Dominique Cassini observed the division between what are called the A and B rings of Saturn. It is now known that the gravitational influence Saturn’s moon Mimas is responsible for this 4,800 mile-wide division, known as the Cassini division.
Saturn’s volume is 755 times greater than that of Earth. The winds of the planets’ upper atmosphere can reach up to 500 m/s, four and half times the speed of the fastest hurricane on Earth! Combined with heat rising up from the planet’s interior, these winds create the yellow and gold bands of the atmosphere. A day on Saturn lasts 10.7 hours and one year is equivalent to 29 Earth years.
Saturn’s rings are composed predominantly of water ice. The rings contain more than 23 times as much water as all the oceans of Earth. They consist of seven separate ring structures extending up to 282,000 km from the planet; about three quarters of the distance between Earth and the moon. The depth of the ring system is approximately 10 meters.
Saturn has 62 known moons. The largest moon, Titan, is bigger than the planet Mercury and the second largest moon in the solar system (only Jupiter’s Ganymede is bigger). Titan has a thick nitrogen atmosphere, similar to the early atmosphere of Earth. On Titan, the cold atmosphere causes methane — a normally gaseous compound on earth — to precipitate out of the atmosphere as rain. Titan has large lakes of methane and planetary scientists are interested in it because of its potential to harbor basic life. Further study of Titan may help scientists to better understand early Earth. Titan is the only other moon in the solar system where NASA has landed a probe.
Saturn’s moon Titan was discovered by Christian Huygens in the year 1655. Giovanni Cassini followed up with the discovery of the next four moons: Iapetus, Rhea, Dione and Tethys. In 1784 William Herschel discovered Mimas and didn’t sell at this. More than 50 years had passed before the discovery of Hyperion and Phoebe. As the size and resolving capacity of telescopes increased, so too did the number of discoveries of new moons around Saturn. Additional discoveries came via robotic probes, such as the Cassini mission earlier this century.
Iapetus is a two-faced world — having one side that is highly reflective and as white as snow and another side as dark as black velvet. Mimas has an enormous impact crater on one side that nearly split the moon and half. The moon Enceladus has a fractured surface where water can escape, through evaporation, into the atmosphere. This displays evidence of active volcanism on the planet. Phoebe and several other moons, orbits retrograde to the planet. Sixteen of Saturn’s moons orbit and a tidal lock with the world, always keeping one face toward the planet.
Studies by NASA’s Cassini probe indicate that Saturn has a dense core of rock and ice, solidified by Saturn’s intense pressure. The core is surrounded by a metallic liquid hydrogen layer — similar to that of Jupiter, but considerably smaller. Saturn’s magnetic field is 578 times as powerful as that of Earth, but still smaller than Jupiter’s.
The rings, and most of the moons lie totally within the influence of the planet’s magnetosphere. The magnetosphere is a magnetic field surrounding a planet, where electrically charged particles of the solar wind interact with the magnetic fields of the planet. This is the area in which planetary auroras are created.
Saturn can be easily observed through a small telescope, making it accessible to anyone. The deadline for our observing season, however, may be closing within the next month as monsoons begin to dominate our southwestern sky. The planet reaches opposition on the morning of June 3 at 1:00 AM. But any time throughout the month of June and the entire summer will be good for seeing the planet, which is available to us until October.
TAAA Support of Public Mercury Transit Event At Brandi Fenton Memorial Park
By Jim O’Connor
Pictures by Jim Knoll
TAAA has a long history of supporting Pima County Natural Resources/Parks and Recreation and their active astronomical outreach programs. Usually these events are at either the Ironwood Picnic Area on the West Side, or Agua Caliente Park on the East side. For the Mercury transit, however, the venue would be Pima County’s Brandi Fenton Memorial Park. TAAA has performed public Astronomy Festivals at that location in the past, so it was a familiar location.
The event was scheduled from 8 AM through 10 AM, which was a segment in the middle of the transit. The transit itself was forecast to occur from 4:12 AM through 11:42 AM, with sunrise around 5:35 AM, so most of us planned on being there at our earliest convenience, and to stay through the end of the event.
I tried to arrive by 6:30 AM, but my guess on how long the drive would take was wrong, and I didn’t show up until around 6:40. Alan Klus had his dual mount already on the sun, while Jim and Sue Knoll were finishing their setup. As I was setting up, Ron Brewster and Bill Yohey arrived and began setting up, as well as a young lady with a 10” Dobsonian reflector who I did not recognize. We ended up with a mix of white light and H-Alpha scopes. I thought about both options, and while my white light choice would be 90mm, larger than my 60mm Lunt solar scope, I also wanted to take a chance on more solar artifacts being available in the Lunt. Jim Knoll also has Lunt 60mm, but while I have a B600 blocking filter, Jim has a B1200, resulting in a tighter frequency band and more detail in his images. This holds true in eyepiece views, but I push mine through a Mallincam Xterminator, and the resulting image in the attached 19” monitor does well at pulling out details. Unfortunately, I left my laptop and camera home, so I couldn’t capture transit images, nor any of the crowd we had attending the event. Jim Knoll provided some photos he took.
As soon as I got completely set up, the first solar image showed Mercury right where it should be. When Jim commented that he was getting prominences in his view, I altered my exposure time and, sure enough, in my view there were two fountains at the top of my screen, one at approximately 11:30 on the face, and the other at about 12:30. Each was three to four Earth diameters, and resembled spraying fans. Positions on the screen are kind of irrelevant, because not only does the telescope and blocking filter diagonal provide an image rotation, but the image orientation itself is dependent on the orientation of the camera in the eyepiece opening. I readjusted the shutter speed to lose the prominences but highlight the surface characteristics. The sun itself was very entertaining, with multiple wide, long, and arching filament groups and several dynamic, bright white active regions. During the morning, I had about 65 or more visitors. Everyone was amazed at the view, not only the crisp, black disk of Mercury, but all of the other artifacts that varied over time. I had two large poster sets at the table; one had solar characteristics, examples, and stellar evolution, the other had displays of the Mercury transit, an image of Mercury, and a fact sheet about Mercury. The visitors to my setup were all very excited to see not only the transit itself, but all of the solar action. I made sure to tell everyone about Saturday’s TAAA Astronomy Festival at the same location. I was also able to hand out about 10 solar tattoos to young children in the visitor groups. Some of the visitors were bicycle riders and people walking their pets who were pleasantly surprised to find us, and it was a great educational opportunity on the nature of the orbits in the Solar System, and also to discuss stellar evolution. There were even some folks, young and old, who wanted to discuss the varying forms in which stars end their existence. We were not terribly busy, and the chance to spread the information was great to have. Toward the end of the session, after about 10 AM, I enclosed the monitor in a box to cut down on reflections from people’s clothing onto the screen, but the matte surface of the monitor does well on its own to put out a good image, as long as the sun is behind or to the side of the observer. The visitors did seem more comfortable with the shadow box, though. And about a dozen people took smart phone pictures of the great solar images.
Many thanks to Bill Yohey and Jim Knoll for helping me get all my equipment over to the truck after it was all over. And thanks to PCNRP&R for having such a great educational event. We opened a lot of minds, and sparked a bit of curiosity in the crowd that showed up.
South Rim Coordinator
Grand Canyon Star Party
Only one transit observation has trickled in from John Kalas, but will include a surprise below. I’ll include a couple pictures too. Here is John’s:
Mercury Transit – 5/9/16
I awoke at about 7:00 am and took my 11×80 giant binoculars with solar filters out in the backyard to assess the transit and make the big decision of whether or not to lug out the telescope. I should have set up the telescope the night before and left it parked overnight, so it would be accurately aligned for the transit but I was lazy.
The transit was about mid-way, so I decided to get out the scope. By about 8:00 am, the Astro-Physics 130mm refractor with a Thousand Oaks white light solar filter on an A/P 600 mount was ready-to-go. On went the Canon 60Da DSLR camera at prime focus and I started experimenting with the manual settings of exposure time and ISO speeds. After several trips into the house with the camera’s memory card to review the images on the computer, I settled on 1/8000th of a second exposure time and an ISO of 1600. Being that I didn’t have a precise polar alignment, I had to slightly re-align the sun in the camera’s view finder for every shot. Shown here is the start image and the last image.
A Few Shots from the Mercury Transit
With the Mercury transit already underway at sunrise, I was visualizing a shot of “Mercury rise” as it cleared the Catalina Mountains, so on Saturday I scouted a few locations for a clear view – tough to find in the metropolitan area with trees, power lines and easy access. I finally found one near the east end of Roger where it meets the Rillito Wash near UA Farms.
Since I never use an alarm clock, I actually had to test it to see if it worked for my 4:50 wake-up call so I could drive the mile or two and set up. Conditions looked great – the picture at left shows my setup – the TEC 140 (plus 1.4X Canon extender) on my Alt-Az mount, with the location on the right slope of a hill. The shot, close to my visualization, except for perhaps a saguaro or two, is shown at right. Mercury had just cleared the slope at lower left.
What is interesting to me are some of the atmospheric effects of the low sun. We all know about the “green flash” as the atmospheric dispersion gives any setting object a green or blue upper edge and a red lower edge. You can see it on the above image. But if you examine the image of Mercury, or even the sunspot, you can see the inky spot has a reddish upper edge, and blue/green lower! Of course it is caused not by the black dot, but rather the illuminated upper edge of the lower edge of Mercury is green… An enlargement is shown at left.
At his point I retired to home, where I had setup and aligned the AP1200 the night before in the back yard. Spending about 30 minutes figuring why the scope wasn’t tracking (Duh – in my sleep-addled state I’d hooked it up wrong!). Eventually I got underway – fortunately the trees blocked the low sun, so I got going about mid-transit. So I’ve got hundreds of images thru the thing – perhaps they’ll get turned into a movie someday. Shown here is a 2-image stack very near 3rd contact showing a full-resolution shot of the TEC+1.4X extender+Canon XSi camera. I couldn’t be happier with the resolution, just my processing skills how to proceed with a few hundred images!
I hope all who had a chance to observe had a great Transit!
Oh Yea – the surprise!
Since Tom Polakis just spoke to the TAAA 5 weeks ago about time-lapse imaging, I’ve absolutely GOT to show you his treatment of today’s transit! Using a Lunt100, he took high-speed video of the last 10 minutes including egress, and used about half the frames to make 31 frames of fantastic! Gif is shown here, and the link to his pbase gallery is here. “Mike drop” here… Just amazing!
Most Tucson amateur astronomers know what happens on the first Friday of the month – the monthly meeting of the Tucson Amateur Astronomy Association (TAAA)! Arguably living in the astronomy capital of the world, we have some pretty good meetings. With the Kitt Peak National Observatory, the Planetary Sciences Institute, Steward Observatory and the Lunar and Planetary Lab all headquartered in central Tucson, we are rarely lacking for world-class lectures about the universe or latest data from spacecraft. We even get great lectures from TAAA members themselves, some of them working at the above institutions!
Last night was the first Friday, so of course, we got together, but our normal lecture hall at Steward Observatory was being used for final exams – it is that time of year! So we arranged to meet across the street at the auditorium of the Lunar and Planetary Laboratory. The location fell into the theme of the evening – celebrating the history of LPL. The traditional Beginner’s Lecture was a showing of the great documentary “Desert Moon”, a 2014 movie by Jason Davis. Using archival footage as well as interviews with early employees, it tells the story of how LPL played a central role in the space race and eventual landing on the Moon. Gerard Kuiper, who founded LPL in 1960 is at center in the right image, and Ewen Whitaker, one of the main interviewees, is at right.
The movie is a testament to Kuiper’s leadership and assembling this team around him, most just barely out of their teens! They played central roles as Kennedy surprised scientists by declaring the Moon as a goal for NASA. Starting with the lunar atlas Kuiper started at Yerkes Observatory, after founding LPL they supported virtually all the lunar missions leading up to the landing. Fortunately, the movie Desert Moon is free for viewing on-line, and at 35 minutes long, is a great watch, even on a computer screen. My favorite scene is the un-narrated final scene when some of the now “old-timers” who played such central roles, put their swagger on and strutted down the University Mall – shown at left!
The main meeting started promptly at 7:30, and after a few announcements and business (Springtime Board Elections!) the main lecture started – given by LPL director Timothy Swindle. He admitted that the first half dozen slides of his normal talk were well covered by “Desert Moon”, so modified his presentation somewhat. He also announced that much of what he presented was covered in a recent book, recently published by UA press – Under Desert Skies by Melissa Sevigny. Reading her book would likely be a great addition to the information gleaned from Dr. Swindle’s presentation.
Dr. Swindle points to the launch of Sputnik in the 50s, and the 6 week period in Spring of ’61 in forming the direction of LPL’s mission to the Moon and beyond. So the developing space race kept funding levels high and the department focused both on the Moon and a fledgling planetary space program. After the successes in the Moon landings, UA continued involvement in the Pioneer, Voyager, Cassini and Mars missions.
He told the story of Lujendra Ojha, an undergraduate from Nepal working on a student project with data from HiRISE, under the direction of principle investigator Alfred McEwen, and discovered “streaks” on the inner walls of craters and gorges that follow up spectroscopy showed was briny water – one of the first direct indicators of water on Mars.
He also told the story of Richard Kowalski. One of the primary research works of Steward and LPL consists of searching for Near-Earth Asteroids with the Spacewatch and Catalina Sky Surveys. Kowalski is the ONLY observer to discover objects BEFORE they struck the Earth, one exploding over Sudan, the other striking the Atlantic Ocean. He is shown at right holding a small piece of the asteroid/meteor that landed over Sudan.
He closed out his talk with the latest mission coming out of LPL – the OSIRIS-REx mapping and sample return mission to an asteroid. Facing a launch this September, it arrives at Bennu in 2018, and returning with its precious cargo in 2023. Answering questions for a good long time, it was a great talk and enjoyed by all.
After the meeting’s conclusion, most stayed to interact outside the auditorium over snacks. Another great meeting! The next one will be the day before the Grand Canyon Star Party starts the first weekend of June!
A rather rare event will be happening on Monday May 9 — Mercury will appear to move across the face of the Sun. For us in Tucson, the transit will already be underway when the Sun rises at 5:32 am. The Tucson Amateur Astronomy Association (TAAA) will have several Solar Telescopes set up at Brandi Fenton Memorial Park starting about 7:30 am. We’ll be there until at least 10 am, but will hang around as long as there are people interested in viewing the Transit. The Mercury Transit will end at 11:39 am Tucson time.
Mercury Transits are fairly rare, with only 13 or 14 per Century. The last Mercury Transit was November 8, 2006 and the next one will be November 11, 2019. After that, we’ll have to wait until 2032 for the next one. Mercury Transits only happen within a few days of May 8 or November 10 of any given year. The reason they don’t happen every year is because Mercury’s orbit is inclined 7 degrees to Earth’s Orbit, so most of the time, Mercury transits just above or below the Sun from our perspective.
Join TAAA at Brandi Fenton Memorial Park on Monday May 9th to view this rare event.
Join the Tucson Amateur Astronomy Association (TAAA) on May 14th, from Noon to 9 pm at Brandi Fenton Memorial Park to celebrate National Astronomy Day. This will be a fun-filled day and evening for the entire family. We will have solar telescopes for safe viewing of the Sun and interactive exhibits for everyone during the afternoon. There will be telescopes for viewing deep sky objects in the evening such as Jupiter, star clusters, galaxies, nebulae, and Mars (late evening). We will have a door prize drawing at 7 pm for a 50mm telescope (must be present to win) and a Walk Around the Night Sky presentation around 7:30 pm. The complete schedule is below.
Safe Solar Viewing of the Sun Noon – 6:30 pm
Interactive Astronomy Exhibits Noon – 6 pm
Make Pocket Solar Systems & Sun Dials
Make an impact crater
Door Prize Drawing (must be present to win) 7 pm
50 mm Refractor Telescope
Night Sky Viewing 7:30 – 9 pm
Walk Around the Night Sky Presentation 7:30 pm
Help with personal Telescope All Day/Evening
Bring your personal telescope to receive
assistance in setup & operation