Mariner 4's flyby of Mars.
Stockton Astronomical Society
Valley Skies - September 2006 Issue
Time to Bite the Bullet...
When I joined the SAS in 1989, annual dues were $15-and had been $15 for many years prior to that. In 2006, dues are still $15!
When you consider the membership benefits and resources that have been added over the last fifteen years - free loaner telescopes, an SAS web site, and a 12-page monthly newsletter-it should come as no surprise that the Executive Committee is now recommending an increase in annual dues.
Dues alone have not covered the operating budget for the last several years, as various expenses have steadily climbed. Donations in response to school star parties, plus several generous individual donations-including an anonymous gift specifically targeted to avoiding a dues increase this year-have enabled us to defer the inevitable.
However, at its last meeting, the Executive Committee decided that it is indeed time to recommend an increase in annual dues, starting with the 2007 membership year.
Notice of Proposed Dues Increase:
A formal recommendation will be presented to members attending the September 14 general meeting to approve an increase in the "Basic" or General membership rate to $20 per year. The Committee recommends leaving the Student rate at $10 per year.
A simple majority vote of members present at the September 14, 2006 meeting will decide the issue.
[Assuming that members will view the proposed dues increase as reasonable, perhaps even overdue, the renewal rates for magazine subscriptions on page 11 of the newsletter (which require concurrent membership renewal) include the $20/yr membership rate, subject to approval of the increase at the September 14 general meeting.]
...Trevor Atkinson
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Retrospective on the August 10 meeting program
During our last month's program on UFOs I kept squirming and thinking about what various scientists might think (but probably not say out loud) in response.
Good scientists develop a fine sense of when to be skeptical and what to disbelieve. (Here I am paraphrasing what I recall from an article which Isaac Asimov titled "My Built-In Doubter").
The more incredible an idea seems, the more solid must be the evidence supporting it. (I have seen and heard this basic aspect of science from several sources).
It is much easier to believe than to think. (I don't know who first wrote this quip).
...Neil Lark
The Science Directorate at NASA's Marshall Space Flight Center sponsors the Science@NASA web sites. The mission of Science@NASA is to help the public understand how exciting NASA research is and to help NASA scientists fulfill their outreach responsibilities.
Mariner Meteor Mystery, Solved?
August 23, 2006: On July 14, 1965, Mariner 4 swooped over Mars. It was a moment of high drama. Six other probes had already tried to reach the red planet and failed. Since the days of H.G. Wells (War of the Worlds, 1898), people had been hearing about life on Mars, and they were ready to see the canals and cities. The wait was becoming excruciating.
Finally, all was revealed. With flawless precision, Mariner 4 dipped less than 10,000 km above the planet's surface and took 22 pictures. Mars was covered with desert sand and ancient craters. No cities. No canals. No Martians. No one would ever look at the red planet the same way again.
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Mariner 4's flyby of Mars. |
Most histories of the mission end right there, with Mariner 4 buzzing Mars-"the first spacecraft to visit the red planet"-- and throwing cold water on a lot of good science fiction. But there's more to the story. After the flyby, something strange happened to Mariner 4, setting the stage for a 40-year mystery:
Fast-forward to September 15, 1967. Mariner 4 was cruising the dark emptiness between Earth and Mars. Having shot past Mars in '65 without enough fuel to turn around and go back, there was nothing else to do. All was quiet. Fuel was running low. Soon, Mariner 4 would fade into history.
That's when the meteor storm hit.
"For about 45 minutes the spacecraft experienced a shower of meteoroids more intense than any Leonid meteor storm we've ever seen on Earth," according to Bill Cooke, the head of NASA's Meteoroid Environment Office in Huntsville, AL. The impacts ripped away bits of insulation and temporarily changed the craft's orientation in space. "It was a complete surprise."
Think about it. Out in the "emptiness" between Earth and Mars, a region of space astronauts are going to cross one day if NASA's Vision for Space Exploration comes to fruition, lurks a dark stream of meteoroids capable of producing a shower more intense than anything we've seen in centuries of sky watching on Earth. "Until Mariner 4 stumbled onto it," says Cooke, "we had no idea it was there."
For almost 40 years the source of the shower remained a mystery. But now, meteor expert Paul Weigert of the University of Western Ontario may have cracked the case. The culprit, he believes, is a "dark comet" named D/1895 Q1 (Swift) or "D/Swift" for short.
"Comet D/Swift was first seen in August 1895 by the prolific comet hunter Lewis A. Swift," says Weigert. Swift discovered or co-discovered more than a dozen comets, including 109P/Swift-Tuttle, the source of the well-known Perseid meteor shower. Unlike his other comets, however, "D/Swift quickly vanished. The comet was last spotted in February 1896 heading out of the inner Solar System, and it has never been seen since, even though its orbit indicates it should come back and brighten every 5 years or so."
(Note that the prefix D/ indicates a lost or broken-up comet, one that was well-observed on one or more occasions, but which failed to reappear as expected.)
What happened to D/Swift? "The comet may have disintegrated," says Weigert. Comets are notoriously fragile and sometimes a little sunlight is all it takes to make them crumble. Comet D/Swift probably overheated when it passed by the sun in 1895 and later fell apart.
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The Hubble Space Telescope took this picture of Comet 73P/Schwassmann-Wachmann 3 falling apart in April 2006. Perhaps the same thing happened to D/Swift in the 19th century. |
D/Swift was mostly forgotten until last year when Bill Cooke wondered if "some old D/ comet" might be responsible for the Mariner 4 episode. Comets, especially disrupted comets, leave a stream of debris in their wake as they orbit the sun. If Mariner 4 passed through such a stream, "it would have been sandblasted."
He asked Weigert, a friend and colleague, to look into it. Weigert began to examine old comet data and-voilà-"Mariner 4 was close to the orbit of Comet D/Swift at the time of the meteor encounter."
Amazingly, Mariner 4 was not merely close to the comet's orbit, it may have been close to the comet itself. "According to our calculations, the [possibly shattered] nucleus of D/Swift was only 20 million kilometers from the spacecraft." As distances go in the solar system, that's nearby.
"It's like in Star Trek when Enterprise stumbles across a comet in the middle of deep space. Of course, that's crazy," says Cooke. "Space is so big, the chances of running across a comet are almost nil." Yet this may be what happened to Mariner 4.
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An artist's rendering of Mariner 4. |
Mariner's cameras weren't turned on at the time, so a comet could've passed by unnoticed-except for the jostling of comet dust. Telescopes on Earth saw nothing, but that's no surprise. An old, shattered nucleus wouldn't necessarily glow. It all makes sense.
Case closed?
Weigert still has doubts. "The complicating factor is that, because D/Swift was seen for only a short time in 1895-96, its orbit is not terribly well-known. Our extrapolations could be wrong. We're in the process of collecting more observations from 19th century archives and re-analyzing them. Soon, I hope there will be enough information to convict or acquit Comet D/Swift."
This investigation may lead to others. "The space between Earth and Mars is probably criss-crossed by old debris streams," says Cooke. Weigert's methods can be used to find some of them, "so the next meteor storm won't be such a surprise."
Author: Dr. Tony Phillips | Production Editor: Dr. Tony Phillips | Credit: Science@NASA
Deadly Planets
By Patrick L. Barry and Dr. Tony Phillips
About 900 light years from here, there's a rocky planet not much bigger than Earth. It goes around its star once every hundred days, a trifle fast, but not too different from a standard Earth-year. At least two and possibly three other planets circle the same star, forming a complete solar system.
Interested? Don't be. Going there would be the last thing you ever do.
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Artist's concept of a pulsar and surrounding disk of rubble called a "fallback" disk, out of which new planets could form. |
The star is a pulsar, PSR 1257+12, the seething-hot core of a supernova that exploded millions of years ago. Its planets are bathed not in gentle, life-giving sunshine but instead a blistering torrent of X-rays and high-energy particles.
"It would be like trying to live next to Chernobyl," says Charles Beichman, a scientist at JPL and director of the Michelson Science Center at Caltech.
Our own sun emits small amounts of pulsar-like X-rays and high energy particles, but the amount of such radiation coming from a pulsar is "orders of magnitude more," he says. Even for a planet orbiting as far out as the Earth, this radiation could blow away the planet's atmosphere, and even vaporize sand right off the planet's surface.
Astronomer Alex Wolszczan discovered planets around PSR 1257+12 in the 1990s using Puerto Rico's giant Arecibo radio telescope. At first, no one believed worlds could form around pulsars-it was too bizarre. Supernovas were supposed to destroy planets, not create them. Where did these worlds come from?
NASA's Spitzer Space Telescope may have found the solution. Last year, a group of astronomers led by Deepto Chakrabarty of MIT pointed the infrared telescope toward pulsar 4U 0142+61. Data revealed a disk of gas and dust surrounding the central star, probably wreckage from the supernova. It was just the sort of disk that could coalesce to form planets!
As deadly as pulsar planets are, they might also be hauntingly beautiful. The vaporized matter rising from the planets' surfaces could be ionized by the incoming radiation, creating colorful auroras across the sky. And though the pulsar would only appear as a tiny dot in the sky (the pulsar itself is only 20-40 km across), it would be enshrouded in a hazy glow of light emitted by radiation particles as they curve in the pulsar's strong magnetic field.
Wasted beauty? Maybe. Beichman points out the positive: "It's an awful place to try and form planets, but if you can do it there, you can do it anywhere."
More news and images from Spitzer can be found at http://www.spitzer.caltech.edu/. In addition, The Space Place Web site features a cartoon talk show episode starring Michelle Thaller, a scientist on Spitzer. Go to http://spaceplace.nasa.gov/en/kids/live/ for a great place to introduce kids to infrared and the joys of astronomy.
This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
The Sky Publishing Web site carries an article, dateline August 24, 2006, titled:
"Goodbye, Pluto. Hello, "Dwarf Planet"!
Based on the new definition voted on at the IAU meeting in Prague, we now officially have eight planets in our solar system, from Mercury to Neptune. Pluto didn't make the cut.
Pluto, Ceres, 2003 UB313* and other small round objects orbiting the Sun will now be designated "dwarf planets" which, according to the IAU, are not planets. Is that perfectly clear?
Approved by majority vote, a planet in our solar system is now defined as "a celestial body that
What constitutes a planet is a matter of definition. This definition has been a long time coming.
So has the issue been resolved for good? Maybe not.
There is disappointment and dissension within the planet-definition committee. Committee chair Owen J. Gingerich (Harvard-Smithsonian Center for Astrophysics) is quoted as complaining that "the IAU is in the completely ridiculous situation that a dwarf planet is not a planet."
A suggestion to settle on a single-word substitute for "dwarf planet" (such as planetoid or plutoid) didn't even reach formal discussion. A proposal to adopt a dual system of "classical" and "dwarf" planets was rejected by a large majority.
According to a BBC News Web site, "A fierce backlash has begun against the decision by astronomers to strip Pluto of its status as a planet."
"...the lead scientist on Nasa's robotic mission to Pluto has lambasted the ruling, calling it "embarrassing". Dr Alan Stern, who leads the US space agency's New Horizons mission to Pluto and did not vote in Prague, told BBC News: "It's an awful definition; it's sloppy science and it would never pass peer review......I have nothing but ridicule for this decision."
We probably haven't heard the last of this issue.
Read the complete articles at:
Sky & Telescope:
http://skytonight.com/news/home/3728231.html
BBC News:
http://news.bbc.co.uk/2/hi/science/nature/5283956.stm
*2003 UB313 is a Kuiper Belt object somewhat larger than Pluto, discovered by Michael Brown of CalTech. Its discovery sparked the push for a definition of the term 'planet'.
Turning on to School Star Parties
"Whooa .....Coooolll !!!"
It is 10:45 pm on a May evening, and for the first time in two hours it is quiet. I am sitting in the middle of the playground at Madison Elementary School and the Star Party is now over. The SAS volunteers, Andy Bernhard & Tracy Harp, have gone and Frank Wheeler is just pulling out.
Before I pack it up, one last look at Jupiter and the Galilean moons...
Europa is about 20 minutes from slipping behind the magnificent gas deity--"Whoooa ...Coooolll" is right. That is what I heard from kid after kid this evening. Kids, parents, and teachers lined up, sometimes 15 deep, waiting for what was to be for many their first look ever through a telescope, to see in real life what they had seen only in books or on TV. There it was: the photons had left the planet's upper atmosphere over 30 minutes ago and were now bouncing off the mirrors of the scope, focusing on their retinas, and producing the image of Jupiter and 4 little moons, just like with Galileo in 1609. (I wonder what's Latin for "Whoooa Cooooll" ?) It is no wonder the vast majority of them were so excited.
And now that the star party is over, I sit and contemplate the significance of what we did here this evening, and feel good. Frank, Andy, Tracy and I had fired the imaginations of dozens and dozens of children here tonight. They were excited about science. It was Sooo Cooool ! It is now easier for teachers to grab their attention about a subject in which this nation's students have been lagging behind kids from Europe and Asia. We are all aware that our students need to do much better in math and science. Math and science teach critical thinking skills, without which we will become a nation of semi-functional automatons, a third world country.
This nation has led the world in scientific innovation for the last century, but this position is in jeopardy. Scientific innovation fuels the economy. If our children don't have the skills that businesses need to produce the products of tomorrow then those jobs will move to where those skills exist. What will the next generation of Americans do for a living? ("You want fries with that?") We need to develop the next generation of American engineers and the only way to do that is to get the next generation interested in science.
The volunteers for the SAS School Star Parties help bring science alive instead of just sitting on a page in a boring textbook in a closed-in schoolroom.
Last season we struggled to have enough people and scopes for the schools that were interested. This year will bring more requests. We need more volunteers and telescopes; we need you to help with one school party in your area. All we are asking is for one of your evenings. You will not be alone out there with thousands of kids, you will be spending the evening with other volunteers who have done this before.
I know that I was intimidated by the thought of setting up my scope in a schoolyard and having hundreds of kids ask me questions that I didn't know the answer to. But what I experienced was an enjoyable evening with a few of my new friends that helped me learn how to use my scope and learn more about what to look for. But what surprised me most was the infectious enthusiasm that came with the squeals of delight from an eight year old girl who saw Saturn for the first time, followed by the same squeal from her mother.
Do it once and you too will understand the satisfaction that warms my soul right now as I take a last look at Jupiter before I pack away my telescope and sundry gear. I don't even feel the wind that has now turned cold.
I know I made a small but measurable difference in at least one kid's future tonight.
...Doug Christensen
Copyright © 2006 by Stockton Astronomical Society
Last Updated: 9/4/2006
http://astro.sci.uop.edu/~sas/Newsletter/VS0609.html
