roanoke valley astronomical societyvolume 31—number 6 june 2014 roanoke valley astronomical...
TRANSCRIPT
Volume 31—Number 6 June 2014
Roanoke Valley Astronomical
Society Amateur Astronomy News and Views
In Southwestern Virginia
RVAS NL— June 2014— Pg 1 of 10
Among the many titles to his credit, Dwight Holland is a
PhD, an MD and founder and principal of Human Factors
Associates, Inc. It’s a year and a half since he last
spoke at an RVAS meeting. In November 2012 his topic
was the history, science and future of meteor impacts.
At our May 19th meeting Dr. Holland again visited the
RVAS, speaking this time about the field in which he’s
built a career and expert reputation: human-systems
integration. His focus was the crash almost 50 years
ago of what many regard as the world’s first space
plane—what we learned from it then and what we can
learn from it now.
On November 15, 1967, the third of three U.S. X-15
experimental rocket planes crashed, taking the life of
its veteran and highly skilled pilot, Mike Adams. Built
to determine how aircraft structures, materials, and (Meeting Continued on page 4)
RVAS May Meeting Notes
Holland Explores the X-15 Mishap
By Roger Pommerenke and Frank Baratta
Dr. Dwight Holland (left) and RVAS President Frank Baratta bring
up our speaker’s PowerPoint as members arrive for the May meet-
ing.
Photo by Carolyn Baratta
His X-15 model in the inverted orientation of the plane moments
before its crash, Dr. Holland points out elements of the 1967
mishap that took the life of pilot Mike Adams.
Photo by Roger Pommerenke
The Roanoke Valley Astronomical Society is a membership organization of amateur astronomers dedicated to the pursuit of observational and photographic astronomical activities. Meetings are held at 7:30 p.m. on the third Monday of each month. See calendar on last page of news-
letter for location. Meetings are open to the public. Observing sessions are held one or two weekends a month at a dark-sky site. Yearly dues are: Individual, $20.00; Senior Individual, $18.00; Family, $25.00; Senior Family, $22.00; Student, $10.00. Articles, quotes, etc. published in the
newsletter do not necessarily reflect the views of the RVAS or its editor.
Officers/Executive Committee/Editor/Webmaster Frank Baratta, President ([email protected] )
Sharon Stinnette, Vice President ([email protected]) Rick Rader, Secretary ([email protected]) Jeff Suhr, Treasurer ([email protected])
Carol Mesimer, Member at Large ([email protected])
Michael Good, Immediate Past President ([email protected]) Paul Caffrey, Past President ([email protected])
David E. Thomas, RVAS Newsletter Editor ([email protected])
Roger Pommerenke & David E. Thomas, Webmaster ([email protected])
RVAS web page: http://rvasclub.org
RVAS NL— June 2014— Pg 2 of 10
Sorry, I couldn’t resist. As those of you who regular-
ly attend our meetings and activities know, I have a
tendency to make references to being Italian. But,
though both of my parents were Italian and fluent in
the language, I never learned very much of it. So,
here I am, closing in on age 69, working at learning
Italian.
As I conclude these two years as RVAS President,
I’ve been considering what to say in my message for
this newsletter issue. Naturally, you’d
expect that I’d express certain appre-
ciations and future encouragements—
and, most certainly, I will, shortly.
However, as I sat down to begin writ-
ing, the Italian phrase I’ve chosen for a
title popped into my mind. It happens
to be the January 5th phrase from a
2011 “365 Days of Italian Phrases”
desk calendar that I decided to hold on
to, and am now glad that I did. It can
be translated as “I thoroughly enjoyed
myself!”
I’ve been a member of the RVAS for almost 28 con-
secutive years. (There are just a handful of us cur-
rent members remaining from that vintage.) Newslet-
ter editor from 1990 to 2000 and President three
times now in those 28 years, I can’t remember having
more fun than during these last two. (And that in-
cludes some rollickingly good times back in the 1990s
when we used to stargaze at Carter’s Farm.) I have
thoroughly enjoyed myself!
It’s partly a matter of retiring at the end of 2011 and
the luxury of having the time to devote to club af-
fairs when I became President in July 2012. It’s also
a matter of having a great bunch of people to work
with on our Executive Committee. But perhaps the
most fun has come from the support
I’ve received from the entire member-
ship. You’ve made it fun! The friendly
and welcoming atmosphere that others
before my latest term set in motion,
we’ve built on. I don’t think a guest (or
member) can join us for an evening and
not experience that.
And you’ve turned out for meetings and
activities in numbers that evidence
your interest in being present and in
contact with each other. I feel espe-
cially grateful that an average of 26
members and guests has attended our monthly gath-
erings during these two years. Moreover, the average
attending increased from 25 for 2012-2013 to 28 so
far during 2013-2014. These numbers include our (Message Continued on page 3)
President’s Message
Mi Sono Proprio Divertito!
RVAS NL— June 2014— Pg 3 of 10
annual picnic and star party, which drew 30 in October
2012 and nearly 40 in 2013. Also, during these two
years we added 17 new memberships (9 Family and 8
Individual). To me, this says a lot about how we regard
what the RVAS offers and whether we feel it’s worthy
of our time, effort and participation—and dues!
As I said, I’ve been fortunate to work with a highly
supportive group of people, including officers Sharon
Stinnette, Vice President; Rick Rader, Secretary; Jeff
Suhr, Treasurer; and Carol Mesimer, Executive Com-
mittee Member at Large. Rounding out our Executive
Committee have been Michael Good, Immediate Past
President, and Paul Caffrey Past President. Along with
them, I’ve also had the good fortune during my term to
have had Dave Thomas as our Newsletter Editor and
Web Master and Roger Pommerenke as Co-Web Mas-
ter. And while another couple dozen could be added to
this list, forgive me for only singling out three: John
and Genevieve Goss and Mark Hodges, on whom I have
called for assistance from the beginning and regularly.
Every one of these individuals has contributed greatly
to the events, activities and business of the RVAS
these last two years.
At our June 16th meeting, the slate of 2014-2015 offic-
ers, running unopposed and topped by Michael Good for
President, will be put to those attending for acceptance
by acclamation. Michael is joined by Rand Bowden for
Vice President and Dan Chrisman for Secretary, with
Jeff Suhr and Carol Mesimer seeking to carry on as
Treasurer and Executive Committee Member at Large,
respectively. Dave Thomas and Roger Pommerenke are
continuing in their capacities. I hope you will extend
the same—and more!—support to Michael and all as you
have to me and the other 2012-2014 leaders. Please be
especially supportive to Rand, a major part of whose
duties as Vice President will be to identify and line up
our programs. It’s not an easy task, so please be giving
of your time and effort as he seeks members and out-
side speakers.
Speaking of meetings and programs, as you’ve read in
the May meeting notes, June 16th is our Summer Sol-
stice Social! It’s the first of two such semi-annual
gatherings meant to bring members together for an
easy-going evening. Bring some munchies to share. The
RVAS will provide the beverages. And, while you’re at
it, put some of your latest astrophotos on a flash drive,
grab an astro-gizmo you’ve just acquired, copy to DVD
an interesting short astro-video you just saw or what-
ever, and get them ready for “open mic” time at the
June meeting. It’s my last one as President and I’m
hoping to have a fun time with everyone!
Once again, thanks to all of you for your support these
last two years. Mi sono proprio divertito!
(Message Continued from page 2)
Frank Baratta
control surfaces would perform at hypersonic (Mach 5+)
speeds and very high altitudes, lessons learned from the
X-15 program helped NASA plan other programs such as
Apollo and the Space Shuttle. Holland is co-author of
the 2011 book Breaking the Mishap Chain—case studies
of experimental aircraft, aerospace vehicles, and space-
craft mishaps in which human factors played a signifi-
cant role, including details of the fatal X-15 flight.
Meant to fly in both the atmosphere and space
(considered by the U.S. to start at 50 miles altitude),
the X-15 had two joy-sticks. One—the primary flight
controls—worked the ailerons, elevator and rudder to
control roll, pitch and yaw. But such controls don’t
function above earth’s atmosphere. In space, the X-15
used hydrogen peroxide thrusters for these purposes.
Pilots manually transitioned between joy sticks, using
the first at the beginning and end of the flight and the
other while in space. This complexity may have been a
factor in the crash. The last operational X-15 built, “X-
15-3,” was provided with a crude computer to ease pilot
workload by automatically determining the optimal com-
bination of aerodynamic (e.g. rudder) and ballistic (e.g.
thruster) control. It had previously made several suc-
cessful flights.
Holland reconstructed for us the final moments of the
flight. Beginning normally, as the plane passed 90,000
feet, an electrical disturbance caused the crude com-
puter to fail. Adams decided to continue flying manual-
ly, as he had in the previous two X-15s. Not a big deal,
but it did increase the pilot workload. But then a
scheduled slow wing roll in space to test a camera expe-
rienced more violence than expected. Adams recovered,
and there was still no danger. At this point, overworked
and probably a little shook-up by the test that had not
gone as planned, Adams was supposed to change the po-
sition of a critical flight instrument switch and missed
doing so. The plane soon began slowly drifting to the
right, which Adams did not correct, probably due to los-
ing “mode awareness” from leaving the instrument in the
wrong position. Now coasting in space, the plane began
hurtling sideways at several thousand mph. Eventually
vertical speed was lost and the plane started falling
back to earth. At 230,000 feet and Mach 5 Adams ra-
dioed he was in a spin. At 120,000 feet the spin was
corrected, but the plane was in an inverted dive (as
shown by how Holland is holding the model X-15 upside
down in the picture accompanying this article).
As bad as the situation was, there was still a chance to
avoid calamity. Except that the failed crude computer
was again controlling the plane. Perhaps Adams could
have saved himself if he’d switched off the troublesome
computer and simply flew manually again, the old fash-
ioned way. Perhaps he was unconscious. But now the g
forces on the plane were building. Eventually the stress
was so great that the plane broke up at 65,000 feet,
going almost Mach 4.
Following the tragedy, the Accident Investigation Board
concluded the crash was caused by pilot error and possi-
ble pilot vertigo. But 25 years after the crash, James
Reason, professor emeritus at the University of Man-
chester, England, developed his famous “Swiss cheese”
model of failure analysis, easily summarized as: There’s
No Single Cause of an Accident. Indeed, as the holes in
layers of cheese slices may align to let air though, so
too the immediately evident “active failures” in a mishap
ignore “latent failures” also present in components of a
system (e.g. organizational, physiological, design) that
threaten performance and safety. Traditional failure
analysis concentrates on unsafe acts by an operator as
the cause of the accident—only the last slice of the
Swiss cheese.
(Meeting continued from page 1)
(Meeting Continued on page 5)
Prof. Reason’s “Swiss cheese” failure analysis model, used by Dr.
Holland and others, along with the Human Factors Analysis and
Classification System, to gain more complete insight into such mis-
haps as the X-15 crash.
RVAS NL— June 2014— Pg 4 of 10
Holland agrees that there is often a chain of failures
and has used Reason’s method and the Human Factors
Analysis and Classification System to take a fresh look
at the old crash. Among the conclusions, the instrument
Adams failed to switch could have been designed
better—he could not tell what it was indicating without
looking at another instrument on a different part of the
panel. In other words display ambiguity was a latent
failure. Then, the crude computer did not fail in a “fail-
safe” mode. Adams did not know it was still controlling
the flight—another latent failure. It is also possible
that Adams had certain physiological susceptibilities
that were not adequately accounted for by the pilot
screening process—yet again, a latent failure. Tragical-
ly hard lessons to learn. and reminders of the complexi-
ties and dangers inherent in the integration of humans
and systems.
Now, approaching the 50-year anniversary of this mis-
hap, commercial entities are becoming the successors to
the X-15—“successors” because, like the X-15, they fly
into space (barely) for a short period of time. Among
these, Holland shared with us his thoughts and videos
about two companies: Virgin Galactic and XCOR Aero-
space. Virgin Galactic’s SpaceShipTwo, a scaled up ver-
sion of its SpaceShipOne spacecraft that claimed the
Ansari X Prize in 2004 by climbing to 100km (62 miles)
altitude, will carry passengers on a 2.5 hour flight
100km high and reach a speed of Mach 3. XCOR’s Lynx
spacecraft will also reach an altitude of 100km for a
half-hour flight. The costs per passenger for Virgin
Galactic is expected to be $200,000 and XCOR,
$95,000! Not exactly commuter class travel yet. Both
companies are targeting their first civilian flights for
sometime in 2015!. If you’d like to view the videos on
these spacecraft, you can do so at:
Virgin Galactic’s Third Powered Flight - YouTube
The Lynx Experience - YouTube
Dr. Holland concluded his talk and took a few questions,
after which he received an enthusiastic round of ap-
plause from the group. We look forward to his next
visit with us!
Following our speaker, RVAS President Frank Baratta
made a few brief announcements:
Election of Officers – The deadline passed with no
members requesting to be added to the candidates
list, so the proposed slate of candidates will be
placed before members at the June 16th meeting for
acceptance by acclamation (voice vote).
Peaks of Otter Request – We have been approached
by the Peaks of Otter concessioner about doing a
monthly public stargaze at their site. The company
also operates the Shenandoah National Park’s facili-
ties and offers a monthly program there that is con-
ducted by volunteers from the Charlottesville As-
tronomical Society. For his or her efforts, the vol-
unteer conducting a session receives a complimen-
tary dinner the night of the program and a free
room for an overnight stay. Similar arrangements
would be expected for RVAS members volunteering
to conduct a monthly program at the Peaks of Ot-
ter. We’ll poll our members to determine whether a
volunteer group can be formed that would allow us
to accept this request.
Membership Renewals – Don’t forget that everyone’s
RVAS membership will need renewing on June 30,
2014. Members have received an e-mail notice re-
minder, accompanied by the latest roster, which in-
cludes your current membership type. Renewals re-
ceived prior to June 30th are most appreciated!
Carol Mesimer reminded everyone that a new meteor
shower (spawned by parent body Comet 209P/LINEAR)
may be visible, weather permitting, the night of May
23/24.
Before adjourning for the evening, Frank noted that the
next meeting on June 16th would be our Summer Sol-
stice Social. The RVAS will provide beverages; mem-
bers are asked to bring a finger food item to share with
the group. In addition to the election of officers, vari-
ous activities are planned for the evening, including
providing “open mic” time for anyone who has a topic or
item of astronomical interest to share with the group.
In July, Clark Thomas will speak on his “Graviton Theory
of Everything,” with Dr. Sara Petty, Virginia Tech as-
tronomer, to appear at the August meeting. Our annual
Picnic and Star Party will be held in September, once
again at the Claytor Nature Study Center, in Bedford.
Make plans to join us on June 16th for our Summer Sol-
stice Social!
(Meeting Continued from page 4)
RVAS NL— June 2014— Pg 5 of 10
In the history of ideas there often is a progression
similar to historical dynasties in Egypt and China: First,
there is the great thought, and then a period of theo-
retical fertility, followed by decay, and then transition
toward a new paradigm.
The latest flavor in astrophysics is the mathematically
clever idea that the universe we experience exists two-
dimensionally on the surface of our universal bubble,
and that the worlds we experience are holograms. Be-
cause the diverse formulations of this dubious inspira-
tion are seductive like French perfume, there are some
highly educated astrophysicists who actually think this
stuff makes sense. I call this end-of-era concept the
surreal paradigm.
Hawking's idea of information shredded, but not lost,
inside a black hole's event horizon has served as inspi-
ration for thinking about the universe itself as like the
inner side of an event horizon. This analogy has multiple
errors, which I have explained elsewhere.
Let us first briefly explain what is meant by this too
clever idea of universal holograms. Then I will list rea-
sons for it being in error. It can also be perceived as a
high-tech return to Plato's Cave.
This surreal paradigm is from string theory with its
multiple dimensions. Einstein's General Relativity intro-
duced his two-dimensional sheets in spacetime, but he
stuck with classical ideas. String theory is mostly com-
posed of complex math, where what you imagine can be
harmonized by theories reverse engineered to come to
the conclusions you want. There is no way to verify this
type of paradigm, except through the tautological
math.
There are multiple sources that well explain the holo-
graphic universe idea for the layperson. Two of them
are this one, and this one.
A hologram "represents a recording of information re-
garding the light that came from the original scene as
scattered in a range of directions rather than from
only one direction, as in a photograph. This allows the
scene to be viewed from a range of different angles, as
if it were still present." The key here is that a cosmic
laser beam is employed, and it interacts with a flat re-
cording medium on a cosmic photographic plate. The
two-dimensional medium is what becomes our virtual
three-dimensional reality. In other words, we don't live
on the Earth; we live in and on Flatland far, far away.
For the sake of brevity, here are some reasons why
this surreal idea on a universal level is mistaken:
(1) Holography as we understand it is limited to what
each laser projects. How can any "laser" interact with
everything in motion, projecting everything in our uni-
verse in every direction?
(2) What could this laser be other than omnipotent
Omniscience? If so, why would such a deity want his/
her Creation to be a mere passive hologram?
(3) The question of holographic free will confronts us
as an illusion, like the dead Michael Jackson hologram
at a recent musical awards show.
(4) This paradigm is far too complex to satisfy the Law
of Parsimony; nor does it bypass Kurt Godel's (???? Continued on page 9)
© 2014
Are We Holograms?
By Clark M. Thomas
RVAS NL— June 2014— Pg 6 of 10
RVAS NL— June 2014— Pg 7 of 10
Stars such as our own (Sol) do not appear from nothing
in the past. Each new star has had a gassy/dusty stellar
nursery. Unlike human families, stars don't have just
one or two siblings. They typically have dozens or hun-
dreds that form from chemically rich clouds. Such a
cloud of gas and enriched dust 4.5 billion years ago was
our birth nursery.
New stellar families express themselves thereafter as
star clusters, mostly as open clusters that don't have a
large amount of gravitational cohesiveness, due to their
small numbers. After some millions of years the siblings
wander away from each other following interactions
with other gas clouds, and even interactions with dark
matter. Only a very few open stellar families survive
beyond a billion years.
Several of the Big Dipper stars are included in the
nearest open cluster. Because it is so close to us it
doesn't look to us like a cluster. Slightly farther away
is the loose Hyades cluster. Farther still is the visually
tighter Pleiades, which is notable for the gas we can
see therein. See this link.
Globular clusters, many of which are ten billion years
old, are among the more ancient structures in our visi-
ble universe. Because of their much larger populations,
globular clusters have plenty of cohesive gravity to
maintain their ball shape for the long run. Some of the
largest even host small black holes. It is likely that
most globular clusters formed from the accumulation of
a number of loose clusters in the early universe. Gravity
formed their round shapes, similar to what we see with
Ceres, the largest asteroid, but not with the less mas-
sive asteroids.
The universe's very earliest dust clouds were all low in
metallicity. That elemental simplicity made it impossible
to form planets such as ours, and certainly impossible
to support life. Those phenomena awaited later genera-
tions of dust clouds enriched by supernovae which had
created complex and heavy atoms. After nine billion
years the universe had birth clouds rich enough in the
heavy atoms we would need to build life.
A lot of celestial shuffling has happened in the last 4.5
billion years. Where have all our stellar relatives gone?
There are two ways to track them down. First, we can
now track in reverse stars over billions of years as they
orbited the core of our Milky Way. Second, each birth
cloud has its own "finger print" of trace chemicals. In
our cloud's case we are looking at candidate stellar
spectra for rare barium and yttrium in the proportion
we see in Sol's spectrum.
Drum roll, please.... And the winning candidate is a star
in the constellation Hercules, like ours in color, with a
visual magnitude 6.46, HD162826. This number is not a
pretty name for a pretty star in our family. Astrono-
mers should come up with a better name. I propose we
also call her "Stella," in honor of Stella Kowalski, in A Streetcar Named Desire.
Although there are other family stars in our galaxy,
Stella is exciting because it is likely the most nearby,
and only 15% more massive than Sol, and because it has
the same metallicity that our solar system sports. As-
tronomers have not found any "hot Jupiters" near it,
and the hunt is just beginning for Earth-sized rocky
planets in its Goldilocks zone. It's 110 light years away,
so we won't be going there any time soon. Nevertheless,
we can see it now with binoculars:
The primary source article for this essay is see this
link. This Discovery News article has a finder map of
sorts for binoculars. That map is a worthless tease, be-
cause you can "see" this star, and still not be able to (Stella Continued on page 8)
By Clark M. Thomas
© May 10, 2014
Stella: Sol's Sister
RVAS NL— June 2014— Pg 8 of 10
distinguish Stella from similarly bright nearby stars.
Therefore, starting with the article-supplied map of
this region of Hercules, I have prepared for you a rep-
resentation of what you would see with a pair of binocu-
lars at 10 power. Note that Stella is in the center
(shown as the diamond), and it is slightly less bright
than its two visually close companions, all three forming
an arc.
Note too that this orientation is only rotationally accu-
rate for this calendar date and time, as circumpolar
stars appear to move around Polaris, the north star,
every day. This rotation rule applies whether you are
using your naked eye, binoculars, or any telescope. How-
ever, the spatial relationship of the three stars to each
other does not change, even though their collective ori-
entation rotates. The three together form a curve, with
Stella being the least bright, and with star 90 Hercules
on the opposite end of the three-stars curve being the
most bright.
The second image below is what you would see with a
Newtonian reflector telescope at 56 power. This type
of scope visually reverses objects in the eyepiece north
and south, and also east and west, due to the path light
takes inside the instrument. By comparison, binoculars,
as shown above, show the same "normal" relationship
that the naked eye sees.
While you are outside, use those binoculars to check out
some more of Nature's amazing beauties. I recommend
the great globular star cluster, M13, also in Hercules.
Then be amazed at all you can see in the Milky Way gal-
axy plane from a moonless dark-sky site. Look toward
the constellation Cygnus.
(Stella Continued from page 7)
RVAS NL— June 2014— Pg 9 of 10
MEMBER NOTES
Grisso Heads West to Boise
One night in February 1997, a clear, moonless sky drew Donnie Grisso to the Blue Ridge Parkway to enjoy the
stars. And he just happened to run into some RVAS members out to do the same. That chance encounter led to
17 years of membership in the Society.
Grisso’s long-term stint with the RVAS came to close late last month when he and his wife, Betty, bid farewell to
Roanoke. A 30-plus-year veteran of G.E. (Billing Department), Donnie retired about a decade ago. For years, he
and Betty had periodically traveled west to Idaho to visit their sons and their families. On May 22nd—their home
in southwest Roanoke County sold and belongings already moved—they began the long two-car drive to their new
home in Boise.
A night sky devotee for as long as he can remember, Donnie stargazes by naked-eye and with his 10x50 binocu-
lars, though he readily appreciates opportunities to view through others’ telescopes. Particularly partial to mete-
or showers and comets, he places the Leonid displays of the late 1990s and early 2000s and 1996’s Comet Hya-
kutake high on the list of his night sky experiences.
Donnie’s looking forward to continuing his enjoyment of the night sky in the Boise area. He notes that the win-
ters are actually fairly mild and that the skies away from the City can be very dark, thanks to sharing some al-
most desert-like conditions with Nevada, on Idaho’s southern border. According to Donnie, “If you could see the
skies out there, you wouldn’t want to leave!”
We’ll miss Donnie and Betty, but we wish them “Clear Skies!” and the very best for the future!
incompleteness theorem.
(5) There are more elegant explanations emerging from
the next intellectual dynasty.
(6) I suspect that much of what has emerged regarding
the hologram thesis is related to the publish-or-perish
culture in academia.
(7) Supersymmetry is faltering from the failure of the
Large Hadron Collider to find a number of supersym-
metric particles, and from a recent Harvard/Yale phys-
ics experiment that casts doubt on the electron's as-
sumed anti-particle.
(8) With 10^500 possible universes in M-theory, and
one hologram universe for us, it is difficult to mesh
them all together.
(9) How did this surreal universe begin, and how will it
end in any way that makes sense?
(10) How can holograms projected many billions of light
years away find each and all of us exactly?
(11) How can such holograms make it here without being
distorted and filtered by the intervening universe?
(12) How can random events, and the existential power
we have to change our destinies, be programmed from
billions of years ago?
In summary, let's flee from the surreal cosmological,
returning to the basic laws of physics and philosophy.
As Carl Sagan said, "Somewhere, something incredible
is waiting to be known." It's not the surreal holographic
universe paradigm. It most likely is the Graviton Theory
of Everything.
(???? Continued from page 6)
RVAS NL— June 2014— Pg 10 of 10
Monthly Calendar
MONTHLY MEETING: June 16th, 7:30 p.m., Center on Church, Downtown Roanoke. It’s
our Summer Solstice Social! We’ll have a variety of activities, including club elections, some
videos, “open mic” time and who knows what else? Join us for an eclectic evening of food, fun
and friends!
RVAS WEEKEND OBSERVING OPPORTUNITIES: Unless otherwise indicated, observing is held at Cahas Moun-
tain Overlook, milepost 139 on the Blue Ridge Parkway.
-- Friday and Saturday, June 20th and 21st. Sunset is at 8:44p.m. Astronomical twilight ends at 10:37 p.m. The
Moon sets at 2:23 p.m. and 3:26 p.m., respectively.
-- Friday and Saturday, June 27th and 28th. Sunset is at 8:44 p.m. Astronomical twilight ends at 10:37 p.m.
The Moon sets at 8:51 p.m. and 9:31 p.m., respectively.
-- Future Sessions: July 18th and 19th; July 25th and 26th.
ROANOKE CITY PARKS and RECREATION PUBLIC STARGAZE: Saturday, June 21st, 9:15 p.m., Cahas
Overlook, Milepost 139 Blue Ridge Parkway. Nonmembers must register with Parks & Rec. at 540-853-2236.
Members can call 540-774-5651 for information. (Next session: July 19th, 9:15 p.m., Cahas Overlook.)
Astro-Quiz
Of the 88 constellations, Crux, the Southern Cross, encloses the smallest portion of the sky within its bounda-
ries. But it’s not visible from our latitude. What is the smallest constellation that we can see?
Answer to Last Month’s Astro-Quiz: When Galileo turned his telescope toward Jupiter in 1609, his observa-
tions would soon lead to the demise of Ptolemy’s geocentric model, which had held sway for more than 1,400
years. Early the following year Galileo confirmed that there were four objects that appeared to be orbiting the
planet. But it was still possible through some contorted means to account for these observations within the Ptol-
emaic system. What sealed its fate was Galileo’s observations that Venus went through a cycle of phases. Ptole-
my’s model could not account for this. (Hat’s off to Dan Chrisman and to Harry Montoro [3rd consecutive month
and counting!] for correctly answering last month’s quiz question!)