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Transcript
San Diego
Astronomy Association
Celebrating Over 40 Years of Astronomical Outreach
Office (619) 645-8940
Observatory (619) 766-9118
http://www.sdaa.org
A Non-Profit Educational Association
P.O. Box 23215, San Diego, CA 92193-3215
December 2010
SDAA Business Meeting
Next meeting will be held at:
3838 Camino del Rio North
Suite 300
San Diego, CA 92108
December 14th at 7 pm
Next Program Meeting
SDAA Annual Banquet
January 22, 2011
6:00-11:30 pm
CONTENTS
December 2010, Vol XLVIII, Issue 11
Published Monthly by the
San Diego Astronomy Association
75¢ /$8.00 year
Incorporated in California in 1963
SDAA Annual Banquet..................................1
Back so Soon?..........................................2
SDAA Board of Dircectors 2011...................3
Star Party Coordinators...............................3
Blue Rings around Red Galaxies...................3
Banquet Invitation.......................................4
November Minutes.......................................5
SDAA Contacts......................................7
December Calendar ......................................8
January Calendar..........................................9
Comet Snowstorm Engulfs Hartley 2.........10
New Life in an Ancient Galaxy.........11
AISIG Gallery...........................................15
The Back Page...........................................16
SDAA Annual Banquet, Saturday January 22nd.
Speaker: Dr. Kevin Grazier, JPL, “Jupiter: Shield or Sniper?”
by Michael Vander Vorst
See old friends and make new ones; eat great food at a wonderful venue; win
incredible door prizes and bid on quality astronomy gear; and perhaps best of all, be
enthralled by a world class speaker. Sound interesting? Please join us on Saturday
evening January 22nd at the Handlery Hotel and Resort for our annual SDAA banquet. To sign up, send in the form in this newsletter, or visit the SDAA.org website.
Dr. Kevin Grazier of NASA’s Jet Propulsion Laboratory will be speaking on “Jupiter: Shield or Sniper?” Traditionally, Jupiter has been seen as protector of the Earth.
The idea is that comets from the outer solar system which might otherwise smash
into the Earth (a la Armageddon and Deep Impact) get sucked into Jupiter’s gravity
well instead and are swallowed up, similar to how comet Shoemaker-Levy collided
with Jupiter in 1994. Now, Kevin and his colleagues have created a detailed simula-
San Diego Astronomy Association
tion of the solar system that suggests that Jupiter might be
responsible for kicking comets towards the inner solar system,
where the Earth lives. This research also has implications for
the search for extraterrestrial life, and especially intelligent life
— up until now, scientists have worried that if a solar system
didn’t have something like a Jupiter, it might be too dangerous
for life to get very far before getting wiped out by an impact.
If Jupiter actually makes things worse for inner planets, we
might be more likely to find life in solar systems without big
gas giants.
Kevin Grazier grew up in Sterling Heights, Michigan. He
earned BS degrees in computer science and geology from
Purdue University. After spending a year writing video games
and then three years in the auto industry—while simultaneously earning another BS in physics at Oakland University—
he returned to Purdue and earned an MS degree in physics.
Kevin then moved on to UCLA to do his doctoral research in
planetary physics, performing long-term, large-scale computer
simulations of early Solar System evolution. While at UCLA,
he worked simultaneously at the RAND Corporation, processing Viking Mars imagery in support of NASA’s Mars Observer
mission. Kevin started at JPL in 1995 as an academic part-time
student, finishing his Ph.D. dissertation in 1997. His first JPL
assignment was to write multi-mission planning and analysis
software—software that won JPL- and NASA-wide awards. He
came to NASA’s Cassini Mission to Saturn as Science System
Engineer in early 1998, and shortly thereafter assumed the additional role of Investigation Scientist for the Cassini Imaging
Science Subsystem. He continues research involving computer
simulations of Solar System dynamics, evolution, and chaos.
Dr. Grazier is active in teaching the public, in particular
children, about science in general, and space in particular.
Depending upon the term, he teaches classes in planetary science, astronomy, cosmology, or the search for extraterrestrial
life at UCLA or Cal State, Los Angeles. He can also be found
performing planetarium presentations at LA’s landmark Griffith Observatory. Dr. Grazier also works in Hollywood. He has
been featured in several documentaries, and currently serves
as the scientific advisor for the PBS animated series The Zula
Patrol, and the Sci-Fi Channel series Eureka and Battlestar
Galactica. He has recently served as author and editor for the
books The Science of Battlestar Galactica, The Science of
Dune, and The Science of Michael Crichton.
Editor’s Note: Dr. Grazier spoke on the Cassinit-Huygens mission at
the 2007 banquet and it was an outstandint talk. Not only did we get
some great information about the mission and extension plans, we were
treated to some great stories rleated to his work with Battlestar Glactica
Page 2
and other TV series. Of all of the great speakers that we have at our
banquets, Dr Grazier is among the very best and I encourage everybody to
attend this year’s banquet. You won’t be disappointed.
Back So Soon?
by Mark Smith
When I gratefully turned the Newsletter Editor job over to
Brian Staples, I let Brian and the board know that I would keep
all of the templates and materials on file so I could put out
newsletters on an as needed basis. It is VERY nice to have a
backup in this job because life can catch up to you and sometimes you just know that it is going to be a stretch to get the
newsletter out on time. Wanting to stay involved in the club
and knowing that Alice Harvey was looking to turn over the
Private Pad Chair, I volunteered to take on that job. Little did I
know that I would be back in the newsletter business so soon.
I got an e-mail from Bob Austin on November 15th saying
that Brian was being forced to stop doing the newsletter for
health reasons and asking if I could step in until a new replacement was found. Brian was a great help to me when I started
doing the newsletter in 2006 and helped me out several times
over the years before offering to take over the publication again
in June of this year. Of course I was willing to do this. Brian
has given a lot to this club over the years and I’m hoping he
manages to beat this. Removing this stressor is the least I could
do.
So, I’m back and now find myself with 2 club jobs. Unfortunately, the hours and crazy schedule of my new job, the reasons
I decided I couldn’t do the Newsletter anymore, are still a
primary force in my life and I still need to divest myself of the
Newsletter Editor job. The job doesn’t take that much more
time than any other club job, but it does occur on a schedule
with almost all of the effort occurring between the 15th and
22nd of each month. It is rewarding, and somewhat humbling, to be the primary voice of the club. The hardest part is
finding content to build the newsletter every month, but there
are several regular features that can be counted on to provide a
base of articles to which the Editor is free to add as the mood
strikes him or her.
If you are interesting in taking over, please contact me for
more details. I will still be available to put out the occasional issues if your computer crashes, you are planning a vacation, or
you know that work is going to prevent you from putting out
a newsletter or two. Having a backup takes most of the stress
out of the job.
SAN DIEGO ASTRONOMY ASSOCIATION NEWS AND NOTES, DECEMBER 2010
San Diego Astronomy Association
A New SDAA Board of Directors for 2011
by Bob Austin
As directed by the SDAA By-Laws, the Nominating Committee was formed in October of this year. The Nominating
Committee successfully found volunteers to fill all positions on
the Board of Directors that are slated to be filled this round.
The positions are set up so that the whole Board does not
change over all at the same time, so that the incoming Board
isn’t in the dark about things in the works that are being carried
over to the new session. The By-Laws also allows for nominations to be made from the floor at the November Program
Meeting, but since no nominations were made from the Membership there will be no need for an election this year.
This year, the positions of President, Vice-President, Corresponding Secretary and the 4 Director positions are slated to
be filled. The Nominating Committee presented the following
as the nominees for the positions: President, Michael Vander
Vorst, Vice President, Bill Carlson, Corresponding Secretary,
Jeff Herman and the 4 Director positions, Bob Austin, Scott
Baker, Mike Finch and Kin Searcy. The positions of Treasurer,
Ed Rumsey and Recording Secretary, Brian McFarland are not
up for election this year, but will fill out the rest of the SDAA
Board of Directors for 2011. This Board will be installed at the
Annual Banquet on January 22, 2011 at the Handlery Hotel and
Resort in Mission Valley.
Star Party Coordinators
by Kin Searcy
One major characteristic of SDAA is our friendliness and
willingness to share our time and talent with the public. You
see this at TDS, AISIG events, KQ Ranch, our program
meetings, and both our standard star parties and “on demand”
star parties that scheduled for school, community, and scout
groups. These star parties are wonderful events both for the
group and for the SDAA volunteers who share their telescopes
and knowledge. We touch many minds through this outreach.
These “on demand” star parties have been traditionally managed by SDAA star party coordinators, who are the
primary point of contact for star parties in their areas: North,
Central, South, and East San Diego. These areas and the names
and contact information for these star party coordinators are
published on the SDAA website so that the public can contact
them directly. Star party coordinators work out dates on the
SDAA calendar that do not conflict with other events, liaison
with the requesting group on details (where to set up, site
access, refreshments, etc.), advertise the star party to SDAA
membership, and monitor weather conditions to make a mutually agreed go/no-go decision for the specific star party.
Coordinators usually attend the star party but are not required
to do so.
At present, SDAA has only two star party coordinators, Kin
Searcy for Central San Diego and Jerry Hilburn for North San
Diego. We urgently need other area coordinators so that this
vital outreach can continue. Until other coordinators are onboard, the SDAA Board has decided on the following
procedure:
I will continue as the Central San Diego star party coordinator as before. In addition, I will be act as overall star party
scheduler for areas that we do not have a coordinator. If a
star party is not in the central or north areas, I will provisionally schedule the date and ask the SDAA membership for a
volunteer who will coordinate that event only. If no volunteer
is forthcoming, then I will contact the requesting group and tell
them that SDAA cannot support the event.
If you have considered becoming a star party coordinator or
being in a pool of people who would coordinate individual star
parties, SDAA needs you NOW. If you would like to discuss
this commitment, please call me at 858 586-0974.
Editor’s Note: The position of Camp with the Stars coordinator is
also open. This program has been higly popular over the years with
people planning their weekend outings around the schedule when SDAA
members will be at the campgrounds with their telescopes. If you are
interested in taking on the Camp with the Stars position, contact Kin or
any SDAA Board member for information.
Blue Rings around Red Galaxies
by Trudy E. Bell and Dr. Tony Phillips
Beautiful flat rings around the planet Saturn are one thing—
but flat rings around entire galaxies?
That is the astonishing discovery that two astronomers,
Samir Salim of Indiana University at Bloomington and R.
Michael Rich of UCLA described in the May 10, 2010, issue of
The Astrophysical Journal Letters.
“For most of the twentieth century, astronomers observing at visible wavelengths saw that galaxies looked either ‘red
and dead’ or ‘blue and new,’” explained Salim. Reddish galaxies
were featureless, shaped mostly like balls or lentils; bluish ones
were magnificent spirals or irregular galaxies.
Elliptical galaxies looked red, astronomers reasoned, because
they had mostly old red giant stars near the end of their life
cycles, and little gas from which new stars could form. Spiral
and irregular galaxies looked blue, however, because they were
Continued on Page 6
SAN DIEGO ASTRONOMY ASSOCIATION NEWS AND NOTES, DECEMBER 2010
Page 3
San Diego Astronomy Association
You are cordially invited to
The San Diego Astronomy Association’s
Annual Banquet
____________________________________________________________
Speaker: Dr. Kevin Grazier of the Jet Propulsion Labratories
Topic: Jupiter: Sheild or Sniper?
Traditionally, Jupiter has been seen as protector of the Earth. The idea is that comets from the
outer solar system which might otherwise smash into the Earth (a la Armageddon and Deep
Impact) get sucked into Jupiter’s gravity well instead and are swallowed up, similar to how comet
Shoemaker-Levy collided with Jupiter in 1994. Now, Kevin and his colleagues have created a
detailed simulation of the solar system that suggests that Jupiter might be responsible for kicking
comets towards the inner solar system, where the Earth lives.
This research also has implications for the search for extraterrestrial life, and especially intelligent
life — up until now, scientists have worried that if a solar system didn’t have something like a
Jupiter, it might be too dangerous for life to get very far before getting wiped out by an impact. If
Jupiter actually makes things worse for inner planets, we might be more likely to find life in solar
systems without big gas giants.
Menu
Choice of Entrees:
Black Jack Flat Iron Steak - Served with Potatoes & Seasonal Vegetables
Pancetta Chicken - w/ Crisp Pancetta Pork Soaked Apples & Seasonal Vegetables
Vegetarian Wellington – Stuffed Pastry Stuffed w/ Roasted Vegetables & Portabella
Mushroooms
SDAA Banquet Order Form
Use this form or order online at http://forms.sdaa.org/banquet.htm
Name______________________________________________________
Address____________________________________________________
City, State, Zip______________________________________________
Telephone__________________________________________________
Email______________________________________________________
Dinner Selections (Enter number of each)
Flat Iron Steak____ Chicken Pancetta ____ Vegetarian Wellington____
Number Attending ____ @ $45 each
Total Payment included $ _________
*Make checks payable to SDAA
Orders must be received no later than 01/18/2010
NO TICKETS WILL BE SOLD AT THE DOOR
Page 4
Mail to:
San Diego Astronomy Association
P.O. Box 23215
San Diego, CA 92123-3215
SAN DIEGO ASTRONOMY ASSOCIATION NEWS AND NOTES, DECEMBER 2010
San Diego Astronomy Association
SDAA Board of Directors Monthly Business Meeting Minutes
9 November 2010 - Preliminary and Subject to Revision.
1. Call to order. The meeting was called to order at 7:04 pm with the following board members in attendance: Bob Austin,
President; Ed Rumsey, Treasurer; Kin Searcy, Corresponding Secretary; Paul Pountney, Director; David Petit, Director; Bill
Carlson, Director.
2. Approval of Last Meeting Minutes. The minutes of October 2010 board meeting were reviewed and approved.
3. Priority / Member Business. None.
4. Standard Reports.
Treasurer’s Report. Accepted as read.
Membership Report. Lost 40 members in October for a new total of 543.
Site Maintenance Report. Nothing to report.
Observatory Report. Jim Traweek trained a large group at the bbq. No one has contacted him about hosting. Mirror
cleaning with the CO2 was a big hit. We need to refill the bottles.
Private Pad Report. Nothing to report.
Outreach Committee Report. Considerable activity with schools in session. Kin is our last star party coordinator.
Cannot continue as currently staffed. As a temporary measure for the non-Central Area; Kin will field all re
quests, accept provisionally, poll membership for a sponsor, Cancel those for which a sponsor is not identified.
Program Report. Program meeting schedule is as follows:
November: Member share, nomination of board
December: No meeting
January: Banquet, Kevin Grazier
February: Gary Petersen
NASA Robotic Observatory. Jerry removed the camera and Bob reports that it has failed. Will forward to SBIG for
repair estimate. It is Jerry’s understanding that the board has offered to pay for the repair, and he will coordinate
with Bob. We had a meeting at TDS and 4 members attended. We have another meeting planned this weekend,
and will be working actively to restore the weather station and computer system on November 13th. We will have
another meeting on November 20th.
Work continues on cleaning the system and determining if other elements of the system are operating correctly.
AISIG Report. No meetings in November or December. Will continue the hands-on sessions with the January
meeting.
Governing Documents Report. Nothing to report.
Newsletter Report. Nothing to report.
Website Report. PB Wiki continues to pose problems. Will look to relocating to Go Daddy and obtaining a refund.
Site Master Plan Committee Report. Will include an advisory ballot item with this year’s election.
5. Old Business.
PA System Purchase. Tabled for next meeting.
Nominating Committee. The nominating committee has completed its work and came up with the following recom
mendation:
President – Brian Staples
Vice President – Bill Carlson
Corresponding Secretary – Jeff Herman
Director – Mike Finch
Director – Kin Searcy
Director – Bob Austin
Director – Scott Baker
Jerry Hilburn will make the announcement at the November Program Meeting and will take nominations from the
floor.
Call for any Old Business. None
6. New Business. None
7. Adjournment. Meeting adjourned at 7:48 pm.
Page 5
SAN DIEGO ASTRONOMY ASSOCIATION NEWS AND NOTES, DECEMBER 2010
San Diego Astronomy Association
Continued from Page 3
rich in gas and dust that were active nurseries birthing hot,
massive, bluish stars.
At least, that’s how galaxies appear in visible light.
As early as the 1970s, though, the first space-borne telescopes sensitive to ultraviolet radiation (UV) revealed something mysterious: a few red elliptical galaxies emitted “a surprising ultraviolet excess,” said Rich. The observations suggested
that some old red galaxies might not be as “dead” as previously
supposed.
To investigate, Salim and Rich used NASA’s Galaxy Evolution Explorer satellite to identify 30 red elliptical galaxies that
also emitted the strongest UV. Then they captured a long, detailed picture of each galaxy using the Hubble Space Telescope.
“Hubble revealed the answer,” says Salim. The UV radiation was emitted by enormous, flat bluish rings that completely
surrounded each reddish galaxy, reminiscent of the rings of
Saturn. In some cases, the bluish rings even showed a faint
spiral structure!
Because the bluish UV rings looked like star-forming spiral
arms and lay mostly beyond the red stars at the centers of the
elliptical galaxies “we concluded that the bluish rings must be
made of hot young stars,” Salim continued. “But if new stars
are still being formed, that means the red-and-dead galaxies
must have acquired some new gas to make them.”
How does a galaxy “acquire some gas?” Salim speculates
that it was an act of theft. Sometimes galaxies have close
encounters. If a gas-rich irregular galaxy passed close to a gaspoor elliptical galaxy, the gravity of the elliptical galaxy could
steal some gas.
Further studies by Galaxy Evolution Explorer, Hubble and
other telescopes are expected to reveal more about the process.
One thing is certain, says Rich: “The evolution of galaxies is
even more surprising and beautiful than we imagined.”
The press release is available at http://www.galex.caltech.edu/
newsroom/glx2010-03f.html. The full published article is “Star
Formation Signatures in Optically Quiescent Early-Type Galaxies” by Samir Salim and R. Michael Rich, The Astrophysical
Journal Letters 714: L290–L294, 2010 May 10.
Point the kids to the Photon Pile-up Game at http://spaceplace.nasa.gov/en/kids/galex/photon, where they can have
fun learning about the particle nature of light.
This article was provided by the Jet Propulsion Laboratory,
California Institute of Technology, under a contract with the
National Aeronautics and Space Administration.
The Galaxy Evolution Explorer UV space telescope helped to identify red elliptical galaxies that also emitted the strongest UV. These are detailed, longexposure Hubble Space Telescope images of four of these galaxies that capture the UV-emitting rings and arcs indicative of new star formation.
Page 6
SAN DIEGO ASTRONOMY ASSOCIATION NEWS AND NOTES, DECEMBER 2010
San Diego Astronomy Association
SDAA Contacts
Club Officers and Directors
President
Vice-President
Recording Secretary
Treasurer
Corresponding Secretary Director Alpha
Director Beta
Director Gamma
Director Delta
Bob Austin
MichaelVander Vorst
Brian McFarland Ed Rumsey
Kin Searcy Bill Carlson Brian Staples
Paul Pountney David Petit
Site Maintenance
Observatory Director
Private Pads
Outreach
N. County Star Parties
S. County Star Parties
E. County Star Parties
Central Area Star Parties
Camp with the Stars
Newsletter
Membership
New Member Mentor
Webmaster
AISIG
Site Acquisition
Field Trips
Grants/Fund Raising
Merchandising
Publicity
Roboscope Director
Governing Documents
TDS Network
Amateur Telescope Making
Bill Quackenbush [email protected]
Jim Traweek [email protected]
Alice Harvey
[email protected]
Kin Searcy
[email protected]
Rafeal de la Torre [email protected]
-Vacant- [email protected]
Bob Affeldt
[email protected]
Kin Searcy
[email protected]
-Vacant- [email protected]
Mark Smith
[email protected]
Bill Carlson
[email protected]
Bill Carlson
Bob Austin
[email protected]
Kin Searcy
[email protected]
Jerry Hilburn
[email protected]
MichaelVander Vorst
[email protected]
Jerry Hilburn
[email protected]
Pau “Moose” Pourtney [email protected]
Jerry Hilburn
[email protected]
Kent Richardson [email protected]
-Vacant- Bill Carlson
[email protected]
Peter DeBaan
[email protected]
SDAA Editorial Staff
Editor - Mark Smith
[email protected]
Assistant Editor: Craig Ewing
Contributing Writers
Trudy E Bell Kin Searcy
Bob Austin Mark Smith
Dr. Tony Phillips
Michael Vander Vorst
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
Committees
(760) 787-1174
(858) 755-5846
(619) 462-4483
(858) 722-3846
(858) 586-0974
(425) 736-8485
(619) 465-7014
(858) 395-9593
(858) 395-1007
(619) 477-7279
(858) 622-1481
(858) 586-0974
(858) 386-8241
(619) 328-2487
(858) 586-0974
(858) 484-0540
(425) 736-8485
(425) 736-8485
(760) 787-1174
(858) 586-0974
(858) 565-4059
(858) 755-5846
(858) 565-4059
(619) 465-7014
(858) 565-4059
(858) 268-9943
(425) 736-8485
(760) 745-0925
Have a great new piece of gear? Read an astronomy-related book that you think
others should know about? How about a photograph of an SDAA Member in
action? Or are you simply tired of seeing these Boxes in the Newsletter rather
than something, well, interesting?
Join the campaign to rid the Newsletter of little boxes by sharing them with the
membership. In return for your efforts, you will get your very own by line or photograph credit in addition to the undying gratitude of the Newsletter Editor. Just
send your article or picture to [email protected] or [email protected]
SAN DIEGO ASTRONOMY ASSOCIATION NEWS AND NOTES, DECEMBER 2010
Page 7
San Diego Astronomy Association
Sunday
Monday
December 2010
Tuesday
Wednesday Thursday
1
Stars in the Park
5
12
6
13
Pepper Drive
Geminid Meteor
Shower
19
20
Saturday
2
3
4
Fletcher
Elementary
TDS Member
Party
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Christmas Eve
Christmas Day
Hearst
Elementary
New Moon
Hanukkah begins
Friday
SDAA Business
Meeting
Darnell Charter
Doyle
Elementary
Stars at Mission
Trails
TDS Public Night
Total Lunar
Eclipse
26
Kwanzaa
Page 8
27
Full Moon
Winter begins
28
29
30
31
New Year's Eve
SAN DIEGO ASTRONOMY ASSOCIATION NEWS AND NOTES, DECEMBER 2010
San Diego Astronomy Association
Sunday
2
Monday
3
New Moon
January 2011
Tuesday
Wednesday
Thursday
Friday
1
4
5
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7
Stars in the Park
Saturday
Sycamore Canyon
New Year's Day
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Lakeview
Elementary
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SDAA Business
Meeting
25
Full Moon
26
Stars at Mission
Trails
Phoenix House
SAN DIEGO ASTRONOMY ASSOCIATION NEWS AND NOTES, DECEMBER 2010
Cub Scout Pack
546 at Anza
Borrego
SDAA Annual
Banquet
Page 9
San Diego Astronomy Association
This contrast-enhanced image obtained during Deep Impact’s Nov. 4th flyby of Comet Hartley 2 reveals a cloud of icy particles
surrounding the comet’s active nucleus.
Comet Snowstorm Engulfs Hartley 2
by Dr. Tony Phillips
[email protected]
NASA has just issued a travel advisory for spacecraft: Watch
out for Comet Hartley 2, it is experiencing a significant winter
snowstorm.
Deep Impact photographed the unexpected tempest when
it flew past the comet’s nucleus on Nov. 4th at a distance of
only 700 km (435 miles). At first, researchers only noticed the
comet’s hyperactive jets. The icy nucleus is studded with them,
flamboyantly spewing carbon dioxide from dozens of sites.
A closer look revealed an even greater marvel, however. The
space around the comet’s core is glistening with chunks of ice
and snow, some of them possibly as large as a basketball.
“We’ve never seen anything like this before,” says University
of Maryland professor Mike A’Hearn, principal investigator of
Deep Impact’s EPOXI mission. “It really took us by surprise.”
Before the flyby of Hartley 2, international spacecraft visited
four other comet cores—Halley, Borrelly, Wild 2, and Tempel
1. None was surrounded by “comet snow.” Tempel 1 is particularly telling because Deep Impact itself performed the flyby.
The very same high resolution, high dynamic range cameras
that recorded snow-chunks swirling around Hartley 2 did not
detect anything similar around Tempel 1.
Page 10
“This is a genuinely new phenomenon,” says science team
member Jessica Sunshine of the University of Maryland.
“Comet Hartley 2 is not like the other comets we’ve visited.”
The ‘snowstorm’ occupies a roughly-spherical volume
centered on Hartley 2’s spinning nucleus. The dumbbell-shaped
nucleus, measuring only 2 km from end to end, is tiny compared to the surrounding swarm. “The ice cloud is a few tens
of kilometers wide--and possibly much larger than that,” says
A’Hearn. “We still don’t know for sure how big it is.”
Data collected by Deep Impact’s onboard infrared spectrometer show without a doubt that the particles are made of frozen
H2O, i.e., ice. Chunks consist of micron-sized ice grains loosely
stuck together in clumps a few centimeters to a few tens of
centimeters wide.
“If you held one in your hand you could easily crush it,” says
Sunshine. “These comet snowballs are very fragile, similar in
density and fluffiness to high-mountain snow on Earth.”
Even a fluffy snowball can cause problems, however, if it
hits you at 12 km/s (27,000 mph). That’s how fast the Deep
Impact probe was screaming past the comet’s nucleus. An
impact with one of Hartley 2’s icy chunks could have damaged
the spacecraft and sent it tumbling, unable to point antennas
toward Earth to transmit data or ask for help. Mission controllers might never have known what went wrong.
SAN DIEGO ASTRONOMY ASSOCIATION NEWS AND NOTES, DECEMBER 2010
San Diego Astronomy Association
only beginning to analyze gigabytes of data beamed back from
the encounter, and new results could be only weeks or months
away.
Stay tuned for updates from Comet Hartley 2.
New Life in an Ancient Galaxy
This plot compares the infrared spectra of particles surrounding Comet
Hartley 2 (black crosses) to spectra of pure water ice grains in the
laboratory (purple lines). Micron-sized grains provide the best match.
What it means: Hartley 2’s snowballs are made of small bits of H20.
“Fortunately, we were out of harm’s way,” notes A’Hearn.
“The snow cloud does not appear to extend out to our encounter distance of 700 km. Sunlight sublimates the icy chunks
before they can get that far away from the nucleus.”
The source of the comet-snow may be the very same garish
jets that first caught everyone’s eye.
The process begins with dry ice in the comet’s crust. Dry
ice is solid CO2, one of Hartley 2’s more abundant substances.
When heat from the sun reaches a pocket of dry ice—poof!—
it instantly transforms from solid to vapor, forming a jet wherever local topography happens to collimate the outrushing gas.
Apparently, these CO2 jets are carrying chunks of snowy water
ice along for the ride.
Because the snow is driven by jets, “it’s snowing up, not
down,” notes science team member Peter Schultz of Brown
University.
Ironically, flying by Hartley 2 might be more dangerous than
actually landing on it. The icy chunks are moving away from
the comet’s surface at only a few m/s (5 to 10 mph). A probe
that matched velocity with the comet’s nucleus in preparation
for landing wouldn’t find the drifting snowballs very dangerous
at all--but a high-speed flyby is another matter. This is something planners of future missions to active comets like Hartley
2 will surely take into account.
Comet snowstorms could be just the first of many discoveries to come. A’Hearn and Sunshine say the research team is
Hubble Science Release
Elliptical galaxies were once thought to be aging star cities
whose star-making heyday was billions of years ago.
But new observations with NASA’s Hubble Space Telescope
are helping to show that elliptical galaxies still have some
youthful vigor left, thanks to encounters with smaller galaxies.
Images of the core of NGC 4150, taken in near-ultraviolet
light with the sharp-eyed Wide Field Camera 3 (WFC3), reveal
streamers of dust and gas and clumps of young, blue stars that
are significantly less than a billion years old. Evidence shows
that the star birth was sparked by a merger with a dwarf galaxy.
The new study helps bolster the emerging view that most
elliptical galaxies have young stars, bringing new life to old
galaxies.
“Elliptical galaxies were thought to have made all of their
stars billions of years ago,” says astronomer Mark Crockett of
the University of Oxford, leader of the Hubble observations.
“They had consumed all their gas to make new stars. Now we
are finding evidence of star birth in many elliptical galaxies,
fueled mostly by cannibalizing smaller galaxies.
“These observations support the theory that galaxies built
themselves up over billions of years by collisions with dwarf
galaxies,” Crockett continues. “NGC 4150 is a dramatic example in our galactic back yard of a common occurrence in the
early universe.”
The Hubble images reveal turbulent activity deep inside the
galaxy’s core. Clusters of young, blue stars trace a ring around
the center that is rotating with the galaxy. The stellar breeding
ground is about 1,300 light-years across. Long strands of dust
are silhouetted against the yellowish core, which is composed
of populations of older stars.
From a Hubble analysis of the stars’ colors, Crockett and his
team calculated that the star-formation boom started about a
billion years ago, a comparatively recent event in cosmological
history. The galaxy’s star-making factory has slowed down since
then.
“We are seeing this galaxy after the major starburst has occurred,” explains team member Joseph Silk of the University
of Oxford. “The most massive stars are already gone. The
youngest stars are between 50 million and 300 to 400 million
years old. By comparison, most of the stars in the galaxy are
around 10 billion years old.”
SAN DIEGO ASTRONOMY ASSOCIATION NEWS AND NOTES, DECEMBER 2010
Page 11
San Diego Astronomy Association
The encounter that triggered the star birth would have been
similar to our Milky Way swallowing the nearby Large Magellanic Cloud.
“We believe that a merger with a small, gas-rich galaxy
around one billion years ago supplied NGC 4150 with the
fuel necessary to form new stars,” says team member Sugata
Kaviraj of the Imperial College London and the University
of Oxford. “The abundance of ‘metals’ -- elements heavier
than hydrogen and helium—in the young stars is very low,
suggesting the galaxy that merged with NGC 4150 was also
metal-poor. This points towards a small, dwarf galaxy, around
one-twentieth the mass of NGC 4150.”
Minor mergers such as this one are more ubiquitous than
interactions between hefty galaxies, the astronomers say. For
every major encounter, there are probably up to 10 times
more frequent clashes between a large and a small galaxy.
Major collisions are easier to see because they create incredible
fireworks: distorted galaxies, long streamers of gas, and dozens
of young star clusters. Smaller interactions are harder to detect
because they leave relatively little trace.
Page 12
Over the past five years, however, ground- and space-based
telescopes have offered hints of fresh star formation in elliptical
galaxies. Ground-based observatories captured the blue glow of
stars in elliptical galaxies, and satellites such as the Galaxy Evolution Explorer (GALEX), which looks in far- and near-ultraviolet
light, confirmed that the blue glow came from fledgling stars much
less than a billion years old. Ultraviolet light traces the glow of hot,
young stars.
Crockett and his team selected NGC 4150 for their Hubble study
because a ground-based spectroscopic analysis gave tantalizing
hints that the galaxy’s core was not a quiet place. The ground-based
survey, called the Spectrographic Areal Unit for Research on Optical Nebulae (SAURON), revealed the presence of young stars and
dynamic activity that was out of sync with the galaxy.
“In visible light, elliptical galaxies such as NGC 4150 look like
normal elliptical galaxies,” Silk says. “But the picture changes when
we look in ultraviolet light. At least a third of all elliptical galaxies
glow with the blue light of young stars.”
Adds Crockett: “Ellipticals are the perfect laboratory for studying
minor mergers in ultraviolet light because they are dominated by
SAN DIEGO ASTRONOMY ASSOCIATION NEWS AND NOTES, DECEMBER 2010
San Diego Astronomy Association
old red stars, allowing astronomers to see the faint blue glow of
young stars.”
The astronomers hope to study other elliptical galaxies in the
SAURON survey to look for the signposts of new star birth.
The team’s results have been accepted for publication in The
Astrophysical Journal.
The Hubble Space Telescope is a project of international
cooperation between NASA and the European Space Agency.
NASA’s Goddard Space Flight Center manages the telescope.
The Space Telescope Science Institute (STScI) conducts
Hubble science operations. STScI is operated for NASA by the
Association of Universities for Research in Astronomy, Inc., in
Washington, D.C.
for Apollo 12,” Rice said. He sent Bean and Gordon photographs that Opportunity took of the two craters.
The images are available online at http://photojournal.jpl.
nasa.gov/catalog/PIA13593 and http://photojournal.jpl.nasa.
gov/catalog/PIA13596. Intrepid crater is about 20 meters (66
feet) in diameter. Yankee Clipper crater is about half that width.
After a two-day stop to photograph the rocks exposed at
Intrepid, Opportunity continued on a long-term trek toward
Endeavour crater, a highly eroded crater about 1,000 times
wider than Intrepid. Endeavour’s name comes from the ship of
James Cook’s first Pacific voyage.
During a drive of 116.9 meters (383.5 feet) on Nov. 14,
Opportunity’s “odometer” passed 25 kilometers (15.53 miles).
That is more than 40 times the driving-distance goal set for Opportunity to accomplish during its original three-month prime
mission in 2004.
NASA Mars Rover Images Honor
Mars Exploration Project Manager John Callas, of NASA’s
Apollo 12
Jet Propulsion Laboratory, Pasadena, Calif., said, “Importantly,
[email protected]
it’s not how far the rovers have gone but how much exploration
NASA’s Mars Exploration Rover Opportunity has visited and and science discovery they have accomplished on behalf of all
photographed two craters informally named for the spacecraft
humankind.”
that carried men to the moon 41 years ago this week.
At the beginning of Opportunity’s mission, the rover landed
Opportunity drove past “Yankee Clipper” crater (see picture inside “Eagle crater,” about the same size as Intrepid crater.
at the bottom of the page) on Nov. 4 and reached “Intrepid
The team’s name for that landing-site crater paid tribute to
crater” on Nov. 9. For NASA’s Apollo 12, the second mission
the lunar module of Apollo 11, the first human landing on
to put humans onto the moon, the command and service mod- the moon. Opportunity spent two months inside Eagle crater,
ule was called Yankee Clipper, piloted by Dick Gordon, and
where it found multiple lines of evidence for a wet environthe lunar module was named Intrepid, piloted by Alan Bean
ment in the area’s ancient past.
and commanded by the late Pete Conrad. The Intrepid landed
The rover team is checking regularly for Opportunity’s
on the moon with Bean and Conrad on Nov. 19, 1969, while
twin, Spirit, in case the increasing daily solar energy available
Yankee Clipper orbited overhead. Their landing came a mere
at Spirit’s location enables the rover to reawaken and resume
four months after Apollo 11’s first lunar landing.
communication. No signal from Spirit has been received since
This week, Bean wrote to the Mars Exploration Rover team: March 22. Spring began last week in the southern hemisphere
“I just talked with Dick Gordon about the wonderful honor
of Mars.
you have bestowed upon our Apollo 12 spacecraft. Forty-one
JPL, a division of the California Institute of Technology in
years ago today, we were approaching the moon in Yankee Clip- Pasadena, manages the Mars Exploration Rovers for the NASA
per with Intrepid in tow. We were excited to have the opportu- Science Mission Directorate, Washington. For more informanity to perform some important exploration of a place in the
tion about the rovers, visit: http://www.nasa.gov/rovers .
universe other than planet Earth where humans had not gone
before. We were anxious to give it our best effort. You and your
team have that same opportunity. Give it your best effort.”
Rover science team member James Rice, of NASA’s Goddard Space Flight Center, Greenbelt, Md., suggested using the
Apollo 12 names. He was applying the rover team’s convention
of using names of historic ships of exploration for the informal names of craters that Opportunity sees in the Meridian
Planum region of Mars.
“The Apollo missions were so inspiring when I was young, I
remember all the dates. When we were approaching these craters, I realized we were getting close to the Nov. 19 anniversary
SAN DIEGO ASTRONOMY ASSOCIATION NEWS AND NOTES, DECEMBER 2010
Page 13
San Diego Astronomy Association
Newsletter Deadline
The deadline to submit articles
for publication is the
15th of each month.
Page 14
SAN DIEGO ASTRONOMY ASSOCIATION NEWS AND NOTES, DECEMBER 2010
San Diego Astronomy Association
AISIG Gallery
Michael Johnson imaged Thor’s Helmet (NGC 2359, Page 14) from TDS using a Celestron C6-NGT and an Orion Star Shoot II. He combined 19 color images of 300 seconds each.
Jim Thommes captured this beautiful view of the familiar Triangulum Galaxy (M33, below) from Blair Valley using a Celestron C8 mounted
on a Losmandy G11 and an SBIG ST8300M CCD camera.
SAN DIEGO ASTRONOMY ASSOCIATION NEWS AND NOTES, DECEMBER 2010
Page 15
San Diego Astronomy Association
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THE BACK PAGE
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: Mead Camera adapter
: Eyepiece color filter set
: Other misc. adaptors for photography
: 2 OM-1 camaras for astral photography
Eyepieces:
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