Southwest Florida Astronomical Society
SWFAS
The Eyepiece
July 2012
A MESSAGE FROM THE PRESIDENT
July has some nice things to observe including natural fireworks!
The planets are hanging in there in the evening sky and some are re-appearing in the morning sky. Mars is getting smaller and dimmer as it approaches Saturn in the evening sky. Catch them while you can. Jupiter and Venus are bright beacons in the morning sky. At the end of the month, the Delta Aquarid meteor shower should provide some nice natural fireworks on July 28th/29th. The summer Milky Way is now well placed for observing.
I would like to thank Carol Stewart for handling camp presentations at Rotary Park and the Calusa Nature Center.
I am checking on the Cape Coral Parks and Rec day to see if we can setup again at the Yacht Club Park on July 28th.
I have been going over the equipment that Mark Kelly provided to the club. The 8” F6 Meade Starfinder is now tracking properly and gives excellent views of the planets. The short tube Celestron4.5” reflector is ready to go. I have added a motor drive to it and it tracks pretty well. The 60mm Meade Alt-Az refractor is shaping up and should be ready shortly. I will have some of the other teaching materials that he provided at the meeting.
Bruce Dissettehas provided a scope for the loan-a-scope program as well that I will be working with.The CPC-800 is available for those interested. It has a large rolling case now that may not fit in some cars. I was able to get it into the back seat of a 4-door Ford Focus, with the tripod in the trunk.
CRP Star Party Schedule for 2012: July 21st, August 18th, September 15th, October 13th, November 10th, and December 15th. Please contact Bruce Dissette if you have any questions.
Carole Holmberg will be giving Thursday evening’s presentation on "Tarantulas and the Tarantula Nebula." She is planning to have a real tarantula at the meeting!
Moon: Full Moon 3rd, Last Quarter 11th, New 19th, 1st Quarter 26th
Club Positions:
President:
Brian Risley
swfasbrisley@embarqmail.
com (239-464-0366)
Vice President:
Bruce Dissette
(239-936-2212)
Secretary:
Kathleen Hendrix
(239-689-8707)
Treasurer:
Tony Heiner
(941-457-9700)
Program Coordinator:
Vacant
Viewing Coords./
Fakahatchee:
Tony Heiner
(941-629-8849)
Chuck Pavlick
(239-560-1516)
Viewing Coord./
Caloosahatchee
Bruce Dissette
(239-936-2212)
Librarian:
Maria Berni
(239-940-2935)
Club Historian:
Danny Secary
(239-470-4764)
Equipment Coordinator:
Brian Risley
swfasbrisley@embarqmail
.com (239-464-0366)
Website Coordinator:
Dan Fitzgerald
(239-282-2292)
Astronomical League Coordinator (ALCOR):
Carol Stewart
(239-772-1688)
Newsletter Editor:
Carole Holmberg
(239-275-3435)
JulyMeeting
Our July monthly meeting will be held on Thursday July 5 at 7:30 pm at Calusa Nature Center and Planetarium. Our program is entitledTarantulas and the Tarantula Nebula.Carole Holmberg will give a PowerPoint about the Tarantula Nebula, the largest known star-forming region in the Local Group of galaxies. A naturalist will also be on hand to show and talk about the Nature Center’s tarantula.
Upcoming Meetings
We have a talk on Spectroscopy “You Can Almost Touch the Stars!” by Tom Field covering amateur spectroscopy equipment scheduled for December. The talk will be a remote presentation.
CRP Star Party Schedule
July 21st, August 18th, September 15th, October 13th, November 10th, and December 15th. Please contact Bruce Dissette if you have any questions.
Mars Science Lab on Track for August Landing
NASA's $2.5 billion Mars Science Laboratory rover is in good shape and on target for a nail-biting seven-minute plunge to a bulls-eye landing on the red planet in early August, thanks to upgraded software and post-launch improvements that will enable the craft to make a more precise descent to the floor of Gale Crater, project scientist John Grotzinger told reporters.
Launched Nov. 26, 2011, the Mars Science Laboratory "Curiosity" rover is the most sophisticated robotic lander ever built, equipped with six electrically-driven wheels, a robot arm, multiple cameras and a suite of state-of-the-art instruments. The goal of the mission, expected to last at least two Earth years, is to explore Gale Crater's intriguing sedimentary formations to help scientists understand whether Mars ever had, or still has, the raw materials and an environment hospitable to life.
Given the distance between Earth and Mars at the time of the rover's arrival, the entry, descent and landing will be carried out autonomously by the craft's main computer. To give engineers insight into the descent, the orbits of three NASA science satellites already circling Mars are being tweaked to make sure they are passing within sight of the rover on landing day to relay telemetry back to Earth.
Curiosity is the size of a small car and weighs nearly 2,000 pounds. It is too big to use an airbag landing system like those employed for the Mars Pathfinder and the Spirit and Opportunity rovers. Instead, engineers came up with the novel sky crane design, lowering the rover directly to the surface attached to a cable unreeled from a rocket-powered descent stage.
"We start the entire process of landing at about 13,200 miles an hour relative to the planet, 78 miles above the surface," said Dave Lavery, MSL program executive. "Hopefully, if all goes well, about seven minutes later we'll be down on the surface with a relative velocity of zero, safely resting on six wheels."
But he cautioned that nothing is guaranteed and that Mars missions have a mixed-bag history of dramatic successes and devastating failures.Historically, only about 40% of the missions to Mars have been successful for any of a number of various different reasons.
The only technical issue has been a Teflon contamination problem in the drill, which was discovered shortly before launch. The drill is mounted in a turret on the end of Curiosity's robot arm. It is designed to operate in rotary or percussive mode, moving rock fragments through the drill's interior and on to an instrument designed to look for signs of carbon compounds.
Testing shows internal Teflon seals can degrade during normal operation, allowing small amounts of Teflon to mix in with the sample material. A detailed analysis indicates the problem will not prevent the drill from being used but it's not yet clear what effect the expected contamination might have on the analysis of soil samples.
- By William Harwood, CBS News
NASA's Next Mars Rover to Face 7 Minutes of Terror
It may be described as reasoned - even genius - engineering. But even the engineers who designed it agree it looks crazy. Six vehicle configurations, 76 pyrotechnic devices, 500,000 lines of code, zero margin for error. What exactly will it take to land NASA's next Mars rover, Curiosity, on the surface of Mars on Aug. 5? The latest video from NASA's Jet Propulsion Laboratory breaks down all "7 minutes of terror."
Watch it at
Titan's Underground Ocean
Data from NASA's Cassini spacecraft have revealed Saturn's moon Titan likely harbors a layer of liquid water under its ice shell.
"Cassini's detection of large tides on Titan leads to the almost inescapable conclusion that there is a hidden ocean at depth," said Luciano Iess, Cassini team member at the Sapienza University of Rome. "The search for water is an important goal in solar system exploration, and now we've spotted another place where it is abundant."
This artist's concept shows a possible scenario for the internal structure of Titan, as suggested by data from NASA's Cassini spacecraft.
The evidence is tidal.Saturn's powerful gravity stretches and deforms Titan as the moon moves around the gas giant planet. If Titan were composed entirely of stiff rock, the gravitational attraction of Saturn should cause bulges, or solid "tides," on the moon only 3 feet in height. Instead, the data show Saturn creates solid tides approximately 30 feet in height. This suggests Titan is not made entirely of solid rocky material.
An ocean layer does not have to be huge or deep to create the observed tides. A liquid layer between the external, deformable shell and a solid mantle would enable Titan to bulge and compress as it orbits Saturn. Because Titan's surface is mostly made of water ice, which is abundant in moons of the outer solar system, scientists believe Titan's ocean is likely mostly liquid water.
On Earth, tides result from the gravitational attraction of the moon and sun pulling on our surface oceans. In the open oceans, those can be as high as two feet. The gravitational pulling by the sun and moon also causes Earth's crust to bulge in solid tides of about 20 inches.
The presence of a subsurface layer of liquid water at Titan is not by itself an indicator for life. Scientists think life is more likely to arise when liquid water is in contact with rock, and these measurements cannot tell whether the ocean bottom is made up of rock or ice.
The results have a bigger implication for the mystery of methane replenishment on Titan. Methane is abundant in Titan's atmosphere, yet researchers believe the methane is unstable, so there must be a supply to maintain its abundance.
"The presence of a liquid water layer in Titan is important because we want to understand how methane is stored in Titan's interior and how it may outgas to the surface," said Cassini team memberJonathan Lunine. "This is important because everything that is unique about Titan derives from the presence of abundant methane, yet the methane in the atmosphere should be destroyed on geologically short timescales."
A liquid water ocean, "salted" with ammonia, could produce buoyant ammonia-water liquids that bubble up through the crust and liberate methane from the ice. Such an ocean could serve also as a deep reservoir for storing methane.
- The full version of this story with accompanying images is at:
Stellar Flare Blasts Exoplanet
A team of astronomers using NASA's Hubble Space Telescope has detected significant changes in the atmosphere of a planet located beyond our solar system.The scientists conclude the atmospheric variations occurred in response to a powerful eruption on the planet's host star, an event observed by NASA's Swift satellite. The stellar flare, which hit the planet like 3 million X-flares from our own sun, blasted material from the planet's atmosphere at a rate of at least 1,000 tons per second.
This artist's rendering illustrates the evaporation of HD 189733b's atmosphere in response to a powerful eruption from its host star. NASA's Hubble Space Telescope detected the escaping gases and NASA's Swift satellite caught the stellar flare. (Credit: NASA's Goddard Space Flight Center)
"The multiwavelength coverage by Hubble and Swift has given us an unprecedented view of the interaction between a flare on an active star and the atmosphere of a giant planet," said researcher Alain Lecavelier des Etangs at the Paris Institute of Astrophysics.
The exoplanet is HD 189733b, a gas giant similar to Jupiter, but about 14% larger and more massive. The planet circles its star at a distance of only 3 million miles, or about 30 times closer than Earth's distance from the sun, and completes an orbit every 2.2 days. Its star, named HD 189733A, is about 80% the size and mass of our sun.Astronomers classify the planet as a "hot Jupiter." Previous Hubble observations show that the planet's deep atmosphere reaches a temperature of about 1,900° Fahrenheit.
HD 189733b periodically passes across, or transits, its parent star, and these events give astronomers an opportunity to probe its atmosphere and environment. In a previous study, Hubble was used to show that hydrogen gas was escaping from the planet's upper atmosphere. The finding made HD 189733b only the second-known "evaporating" exoplanet at the time.The system is just 63 light-years away, so close that its star can be seen with binoculars near the famous Dumbbell Nebula. This makes HD 189733b an ideal target for studying the processes that drive atmospheric escape.
In April 2010, researchers observed a single transit using Hubble's Space Telescope Imaging Spectrograph, but they detected no trace of the planet's atmosphere. Follow-up observations in September 2011 showed a surprising reversal, with striking evidence that a plume of gas was streaming away from the exoplanet at 300,000 mph. At least 1,000 tons of gas were leaving the planet's atmosphere every second.
This turn of events was explained by data from Swift's X-ray Telescope. On Sept. 7, 2011, just eight hours before Hubble observed the transit, Swift was monitoring the star when it unleashed a powerful flare.After accounting for the planet's enormous size, the team notes that HD 189733b encountered about 3 million times as many X-rays as Earth receives from a solar flare at the threshold of the X class.
- Production editor:Dr. Tony Phillips| Credit:Science@NASA
New Way of Probing Exoplanet Atmospheres: Tau Boötis b revealed
For the first time a new technique has allowed astronomers to study the atmosphere of an exoplanet in detail — even though it does not pass in front of its parent star. A team used ESO’s Very Large Telescope to directly catch the faint glow from the planet Tau Boötis b. They have studied the planet’s atmosphere and measured its orbit and mass precisely for the first time — in the process solving a 15-year old problem. Surprisingly, the team also finds that the planet’s atmosphere seems to be cooler higher up, the opposite of what was expected.
The planet Tau Boötis bwas one of the first exoplanets to be discovered back in 1996, and it is still one of the closest exoplanets known. Although its parent star is easily visible with the naked eye, the planet itself certainly is not, and up to now it could only be detected by its gravitational effects on the star. Tau Boötis b is a large “hot Jupiter” planet orbiting very close to its parent star.
Like most exoplanets, this planet does not transit the disc of its star (like the recent transit of Venus). Up to now such transits were essential to allow the study of hot Jupiter atmospheres: when a planet passes in front of its star it imprints the properties of the atmosphere onto the starlight. As no starlight shines through Tau Boötis b’s atmosphere towards us, this means the planet’s atmosphere could not be studied before.
But now, after 15 years of attempting to study the faint glow that is emitted from hot Jupiter exoplanets, astronomers have finally succeeded in reliably probing the structure of the atmosphere of Tau Boötis b and deducing its mass accurately for the first time. The team used the Very Large Telescope (VLT) at ESO’s Paranal Observatory in Chile. They combined high quality infrared observations (at wavelengths around 2.3 microns)with a clever new trick to tease out the weak signal of the planet from the much stronger one from the parent star.
MatteoBrogi (Leiden Observatory, the Netherlands) explains:“Thanks to the high quality observations provided by the VLT and CRIRES we were able to study the spectrum of the system in much more detail than has been possible before. Only about 0.01% of the light we see comes from the planet, and the rest from the star, so this was not easy”.
The majority of planets around other stars were discovered by their gravitational effects on their parent stars, which limits the information that can be gleaned about their mass: they only allow a lower limit to be calculated for a planet’s mass. The new technique pioneered here is much more powerful. Seeing the planet’s light directly has allowed the astronomers to measure the angle of the planet’s orbit and hence work out its mass precisely. By tracing the changes in the planet’s motion as it orbits its star, the team has determined reliably for the first time that Tau Boötis b orbits its host star at an angle of 44° and has a mass six times that of the planet Jupiter in our own Solar System.
“The new VLT observations solve the 15-year old problem of the mass of Tau Boötis b. And the new technique also means that we can now study the atmospheres of exoplanets that don’t transit their stars, as well as measuring their masses accurately, which was impossible before”, says IgnasSnellen (Leiden Observatory, the Netherlands).“This is a big step forward.”
As well as detecting the glow of the atmosphere and measuring Tau Boötis b’s mass, the team has probed its atmosphere and measured the amount of carbon monoxide present, as well as the temperature at different altitudes by means of a comparison between the observations and theoretical models. A surprising result from this work was that the new observations indicated an atmosphere with a temperature that falls higher up. This result is the exact opposite of the temperature inversion — an increase in temperature with height — found for other hot Jupiter exoplanets.
The VLT observations show that high resolution spectroscopy from ground-based telescopes is a valuable tool for a detailed analysis of non-transiting exoplanets’ atmospheres. The detection of different molecules in future will allow astronomers to learn more about the planet’s atmospheric conditions. By making measurements along the planet’s orbit, astronomers may even be able to track atmospheric changes between the planet’s morning and evening.
International Dark-sky Association Membership Promotion
Enter the International Dark-Sky Association’s Darksky Giveaway for an astronomically grand prize— a set of eight TeleVue Ethos eyepieces valued at $5,665, generously donated by Televue Optics.
To enter the IDA's Darksky Giveaway, you must be an IDA member before the entry closeout date of August 31, 2012. If you are not a member, joining is easy and the cost of a one-year membership is only $35.00. To join or renew your membership, visit and select the “Join” tab at the top of the webpage. You can also join by calling the IDA office at (520) 293-3198. Entering to win is also a breeze. Visit darksky.org/giveaway where you can fill out the entry form online and read the official rules.