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 (president@rvasclub.org )

Sharon Stinnette, Vice President (vicepresident@rvasclub.org) Rick Rader, Secretary (secretary@rvasclub.org) Jeff Suhr, Treasurer (treasurer@rvasclub.org)

Carol Mesimer, Member at Large (memberatlarge@rvasclub.org)

Michael Good, Immediate Past President (immediatepastpresident@rvasclub.org) Paul Caffrey, Past President (pastpresident@rvasclub.org)

David E. Thomas, RVAS Newsletter Editor (editor@rvasclub.org)

Roger Pommerenke & David E. Thomas, Webmaster (webmaster@rvasclub.org)

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!)