Download May 2017 - Bays Mountain Park

Bays
Mountain
Astronomy
Club
Edited by Adam Thanz
May 2017
The Monthly Newsletter of the
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Chapter 1
Looking Up
Brandon Stroupe - BMAC Chair
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Brandon Stroupe
Looking Up
Hello BMACers,
Welcome to the month of May. We are inching closer and closer
to the summer season. Some of the days lately already feel like
summer is in full swing. Some like that and some do not. One
good thing about coming into this time of year is the awesome
celestial objects in our sky. This best, in my opinion, would be
the Summer Milky Way. If you are lucky enough to be in good,
dark skies, the Milky Way is just spectacular this time of year.
You can just get lost in the dense stellar dusk of our own
beautiful galaxy. Another aspect of this time of year that some of
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students are chosen to give their presentations at local and
regional science fairs. Some even make it to the national level.
One of the topics for the presentations this year will be on the
rotational period of an asteroid, another will be on the effects of
x-rays on seeds, one will be on a high-altitude balloon launch,
and another will be on an exoplanet transit. I am really looking
forward to these presentations. We seem to never be
disappointed in any of the students’ presentations. Please come
out and show your support for these young minds and their love
for the sciences.
you may look forward to is that this month marks the end of the
At our April meeting, we once again got to enjoy a planetarium
school year. You know who you are! All kidding aside,
show. Everyone saw a special showing of “Comets & Discovery”
congratulations on making it to the end whether you are a
and got to enjoy an always fun, constellation tour. This was
student or a teacher. I wish you luck on all your future endeavors.
aimed to get everyone primed for the StarWatch viewings. I hope
For our meeting this month, we will once again welcome some of
Tom Rutherford’s students. We always reserve the month of May
for Tom to bring a few of his students to give their, in most cases,
award winning presentations. Tom is a member of our Astronomy
everyone was able to make it and had a good time. I,
unfortunately, was unable to be there because I was out of town
on a special trip that I will talk about a little later. Please read the
short review by Adam following my article.
Club, the Bristol Astronomy Club, and a science teacher at
I do want to take a second and apologize to all the members for
Sullivan South High School in Kingsport. Every year, some of his
my absence for the past two months. The first month, I had to
Bays Mountain Astronomy Club Newsletter May 2017
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Virgo
Image from Stellarium
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Bays Mountain Astronomy Club Newsletter May 2017
attend an event for my employer and the second month was
As I mentioned earlier, I was unable to attend last month’s
when I was out of town on a trip. I do promise to avoid missing
meeting because I was on a special trip. The trip I was on was to
any months that I possibly can. I hope that everyone
an astrophotography and astronomy convention. The
understands.
astrophotography convention was called NEAIC (Northeast Astro
Our constellation this month will be Virgo. Virgo is typically linked
to Dike, the Greek goddess of justice, and Persephone, the
daughter of Demeter, the harvest goddess. According to Greek
mythology, the Earth experienced eternal spring until the god of
the underworld abducted the spring maiden Persephone. Another
myth identifies Virgo as Erigone, the daughter of Icarius of
Athens. Icarius, who had been favored by Dionysus, was killed by
his shepherds while they were intoxicated and Erigone hanged
herself in grief. Dionysus placed the father and daughter in the
stars as Boötes and Virgo. Interestingly, Virgo is the largest
constellation of the Zodiac and the second-largest constellation
overall, behind Hydra. Virgo is easily found through its brightest
star, Spica. There is also an abundance of deep-sky objects in
this constellation. Some of them include: M104 (also known as
the Sombrero Galaxy), M49, M58, M59, M60, M61, M84, M86,
M87, M89, and M90. All of these are galaxies, either elliptical or
spiral. And if that wasn’t enough for this constellation, Virgo is
also home to over 26 known exoplanets. This constellation really
does have a lot going on. When you are out this month, be sure
to give Virgo a few minutes of your time.
Imaging Conference) and the astronomy convention was called
NEAF (Northeast Astronomy Forum). Some of you may have
heard of them or may have even been to one or both. If you have
not, I highly recommend taking the time to go one year. The
events are held in Suffern, NY, just outside of New York City. They
are both 2 day events. NEAIC has everything that an astro-imager
dreams of. Presentations, workshops, vendors, and of course,
door prizes. Best of all, you get to meet and talk to the authors of
nearly every astro image you have drooled over in books and
magazines. If you are not interested in astrophotography, NEAF
would be the way to go. It is held in the gymnasium of the local
college and it is massive. Probably close to every vendor and
astronomy related company is set up there. You get to see new,
upcoming products in the astronomy world, talk to the editors of
astronomy magazines, listen to talks from some of the most
notable people in the business, and of course, buy stuff. Trust
me, there is plenty of stuff to buy. Seriously, you could easily go
broke here… I will be happy to talk more about it if you would
like. Just let me know. [Ed.: I think this would be a cool
presentation by both Brandon and Dan…]
That will be it for this month. Just a reminder that the
StarWatches ended in April. I would like to thank everyone that
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Bays Mountain Astronomy Club Newsletter May 2017
NEAF 2017 - All Photos by
Brandon Stroupe
A panorama of NEAF.
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Bays Mountain Astronomy Club Newsletter May 2017
Hercules Telescopes
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Bays Mountain Astronomy Club Newsletter May 2017
NASA
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Bays Mountain Astronomy Club Newsletter May 2017
Sky-Watcher
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Bays Mountain Astronomy Club Newsletter May 2017
Sky-Watcher
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Bays Mountain Astronomy Club Newsletter May 2017
Celestron
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Bays Mountain Astronomy Club Newsletter May 2017
Space.com
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Bays Mountain Astronomy Club Newsletter May 2017
Explora Dome
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Bays Mountain Astronomy Club Newsletter May 2017
iOptron
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Bays Mountain Astronomy Club Newsletter May 2017
TEC (notice their neighbor, the
Antique Telescope Society)
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Bays Mountain Astronomy Club Newsletter May 2017
Solar viewing
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Bays Mountain Astronomy Club Newsletter May 2017
More solar
viewing
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Bays Mountain Astronomy Club Newsletter May 2017
The host site, Rockland
Community College
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Bays Mountain Astronomy Club Newsletter May 2017
took the time to come out and help with showing the public our
longer based on member volunteerism. By 5 p.m., the displays
wonderful night sky. We could not do this without you. The
will be packed up and we’ll all go out to dinner somewhere. Night
SunWatches will continue as usual. If you would like to volunteer
observing will start at 8:30 p.m., but we’ll need to be back to set
to help with the SunWatches, please arrive a little before 3:00
up by 7:30. If you would like to help, please do so! Come at noon
p.m. to help with setup. The scopes are setup at the dam.
to help set up and also see about planning on running a display
Also, as I am writing this, we are coming close to Astronomy Day.
with an astronomical topic of your choice.
It is on April 29th this year. I hope that the day will turn out well
and that we will be able to interact and show many people the
wonders of our great Universe and the great science of
astronomy. Until next month… Clear Skies.
April 2017 meeting review by Adam Thanz:
The April 7th meeting went well. We showed “Comets &
Discovery” and followed that with a shared, “pass the pointer”
activity in which we all pointed to different celestial objects in the
planetarium theater using the Carl Zeiss ZKP-4 star projector.
Many stars, constellations, asterisms, and deep sky objects were
pointed. We even took a dip into the southern sky to enjoy some
lesser-known objects to our members like the Southern Cross
and the Magellanic Clouds!
Astronomy Day is on April 29, 2017. Displays with member
interpretation will be held for the public 1-4:30 p.m. either just
outside the Nature Center or in the main lobby depending on the
weather. But, please show up by noon to help set up. Solar
viewing is officially just the 3-3:30 p.m. time slot, but can be
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Bays Mountain Astronomy Club Newsletter May 2017
Chapter 2
BMAC
Notes
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BMAC News
BMAC Youtube!
The BMAC has a YouTube channel. Click here to see what's on!
(https://www.youtube.com/channel/UCwIQM6nUs9qxJtDQe4AaAWQ)
There are now four entries in our channel. Check them out!
----------------------------------------
Calhoun Stargaze 2017
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breakfast on Sunday. Major financial sponsorship has allowed for
these greatly reduced fees.
https://www.eventbrite.com/e/calhoun-stargaze-2017tickets-32357216305?
ref=enivtefor001&invite=MTE4Nzg2NDMvdGhhbnpAa2luZ3Nwb3
J0dG4uZ292LzA
%3D&utm_source=eb_email&utm_medium=email&utm_campaig
n=inviteformalv2&utm_term=eventpage
Come join regional amateur astronomers at the Calhoun County
Dark Skies Park in West Virginia on Friday May 19th thru Sunday
----------------------------------------
May 21st 2017 for a Starparty Convention.
Calhoun County Park, located just south of Grantsville WV, is one
of the darkest spots in the Eastern U.S. Skies at Calhoun can
easily reach 7th magnitude. The park is located a little NW of the
center of West Virginia, and sits on a ridge with an elevation of
around 1,100-ft.
Attendance for this year is limited to a total of 50 registrations, so
please RSVP no later than Friday, May 5th! The cost of the two
night camping event is only $30 USD per family, and includes
dinner on Friday, three meals on Saturday, and a farewell
Bays Mountain Astronomy Club Newsletter May 2017
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Chapter 3
Celestial
Happenings
Jason Dorfman
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Jason Dorfman
Celestial Happenings
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Last month’s battle between winter and spring has finally ended
I’m sure many of you are just as excited as I am for the upcoming
and spring has emerged victorious! (Big surprise…) Temperatures
total solar eclipse. When this occurs, the Moon is casting its
have warmed a bit in April and with it we are seeing a few more
shadow onto the surface of Earth. There are some fascinating
showers. Hopefully, these April showers will mean more clear
photos taken from ISS and other satellites during an eclipse that
skies in May. Should you find yourself venturing outside on a
show the Moon’s shadow on the surface of Earth. Most of us,
clear night in May, there are a few planets to observe, some
however, will never get the opportunity to venture in space and
close pairings with the Moon, a comet and a weak meteor
see this as its happening. But, we can see this occurring
shower.
elsewhere in the Solar System. Jupiter, with its four Galilean
Planets
Mars continues to shine in the west as it comes to the end of its
year-long appearance in our evening skies. By month’s end, the
“Red Planet” will begin to get lost in the glow of the twilight sky.
It is currently about magnitude 1.6 and will fade to magnitude 1.7
moons and just a slight tilt of its axis, has total solar eclipses
quite regularly. We see these events as shadow crossings on the
surface of Jupiter. This month and next, there will be several twin
shadow crossings that provide a more challenging observation of
the “King of the Planets.” They will occur on:
as the month progresses.
May 11 at 9:59 p.m.
For May, Jupiter is still the dominant planet for evening
May 18 at 11:54 p.m.
observations. Look for it about 35˚ above the southeastern
horizon an hour after sunset. At magnitude -2.4, Jupiter is the
most brilliant point of light in the evening sky.
Bays Mountain Astronomy Club Newsletter May 2017
May 26 at 1:47 a.m.
May 27 at 8:16 p.m.
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The May 27 event involves Io and Ganymede, the largest moon of
the planetarium during the months of May and June for a
Jupiter. The remaining dates feature Io and Europa, the two
informative video about this from NASA.
Galilean moons closest to Jupiter. Look for dark spots on the
cloudtops of the planet. The crossings are brief, lasting 6 to 35
minutes.
This month, it may be worth getting up early for some morning
observations to catch brilliant Venus. Venus reached its maximum
illuminated extent on April 30th and is heading towards its
Saturn rises in the southeast just as Jupiter is crossing the
greatest western elongation on June 3rd. The month opens with
meridian due south around 11:30 p.m. By month’s end, Saturn
Venus at a very bright magnitude -4.7. It will dim slightly to -4.5
will rise two hours earlier. The ringed world is currently in
by month’s end. For telescope and binocular observers, there will
retrograde. It is in Sagittarius and will trek westward into
be lots of visual changes to Venus’ appearance this month. On
Ophiuchus just after mid-month. It is fairly bright at about
May 1, the disk of the planet spans about 38” of sky and shows
magnitude +0.2 for the month. Also, the ring plane is still quite
25% illumination. As the month ends, Venus will have moved
open to us at 26˚.
away from Earth a bit, reducing the apparent diameter of the disk
If you haven’t been keeping up with the Cassini mission at Saturn,
the spacecraft is running low on fuel and has begun its grand
finale. Starting in April and continuing to September, Cassini will
to 25” but increasing the illuminated area to almost half.
Luna
In the beginning of May, we find a crescent Moon in the evening
be making its closest approaches to the planet with several flybys
sky reaching first quarter on May 3. Full Moon occurs on May 10.
between the ring plane and the planet. This will provide the
Be sure to look for it on May 7 when a gibbous Moon passes just
closest look at the inner rings and ultimately the atmosphere of
2˚ north of Jupiter and then on May 13 as it will be 3˚ north of
Saturn. For the last couple of flybys, the craft will skim the cloud
Saturn.
tops and end the mission by burning up as it enters the
atmosphere. The mission team chose this end for Cassini to
Comet 41P/Tuttle-Giacobini-Kresak(T-G-K)
prevent possible contamination from the spacecraft with the
If you didn’t find an opportunity to look for this comet, this may
moons of Saturn that may have favorable conditions for life, such
be the month to make that observation. The comet reached
as Enceladus. Come and see our “Appalachian Skies” program in
perihelion on April 12. Current observations have it at about
magnitude 7, so definitely a binocular or telescope observation.
Some predictions have it reaching mag 6 in early May, but it will
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Bays Mountain Astronomy Club Newsletter May 2017
Comet 41P Tuttle-Giacobini-Kresak on April 2, 2017
The bright star is Thuban; FOV 1.65° x 2.48°; ISO1600, 30s, 130mm refractor, f.l. 819mm, f/6.3
The sky was poor with haze and humidity and the almost first-quarter Moon up. This forced me to a short exposure to keep the sky brightness down. You
can see the green, hazy coma and a small nucleus. The night before was far better with very clear, dark skies and steady, but the comet was still difficult in
binoculars. A faint, green hazy patch with essentially no nucleus. No wonder we didn’t see it during StarWatch on April 1. Photo by Adam Thanz
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Bays Mountain Astronomy Club Newsletter May 2017
most likely dim to mag 8 as we reach the end of the month.
However, the reason to pay attention to this comet is for a
possible outburst, which has occurred with it several times in the
past. During the month, it will be moving southward through
Hercules. [Ed.: The comet is greenish and has a very low surface
brightness. It’s bolometric magnitude may be around 7, but the
coma is probably mag. 10-11. As such, the coma is distended
and is barely viewable with binoculars in a very dark sky. It is also
very difficult with a telescope. I would recommend an RFT or
spotter. See the photo in this issue.]
Eta Aquariids Meteor Shower
This is not a strong shower for the Northern hemisphere with a
medium rate of 10-30 per hour. The peak occurs on the night of
May 6-7 when you may find some swift meteors with persistent
trains, but few fireballs. Unfortunately, there is a waxing gibbous
Moon at that time, so best observations may be in the pre-dawn
hours around 4 a.m. once the Moon has set.
That’s all for this month. Clear Skies!
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Bays Mountain Astronomy Club Newsletter May 2017
Chapter 4
The
Queen
Speaks
Robin Byrne
Robin Byrne
Happy Birthday Elisabeth Hevelius
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One of my holiday gifts this past year was the book “The
planets found so far, we do not resemble what we are finding. We
Copernicus Complex: Our Cosmic Significance in a Universe of
are located at an ideal distance from our star for liquid water to
Planets and Probabilities” by Caleb Scharf. Given our recent trip
be plentiful. We have sufficient atmosphere to maintain liquid
to Poland, seeing the name of Copernicus got me excited.
water and life. We live in an era of the Universe when enough
Although the book turned out to have very little to do with
high mass stars have died to provide, in sufficient quantities, the
Copernicus, it was still an enjoyable and thought-provoking read.
elements necessary for life as we know it to exist. We reside in a
The premise of the book is to explore the question of whether
we, humans on planet Earth, are “special” or not. Prior to
Copernicus and the heliocentric model, people assumed we
were special and that was evidenced by our location at the
galaxy located in a sparsely populated cluster of galaxies, with
infrequent galactic collisions. Our galaxy has enough gas and
dust to sustain star formation. In many ways, it appears as
though, astronomically speaking, we lucked out.
center of all creation. When planet Earth was delegated to just
Having a background in astrobiology, Scharf next explores the
one of the planets orbiting the Sun, the pendulum shifted in the
conditions necessary for life to exist and evolve. I’ll be honest,
other direction, assuming that we are ordinary - a dime a dozen.
since biology is not my strong point, this section was tougher for
Scharf explores a variety of avenues to see whether we are,
me to go through. He looked at the initial chemistry needed to
indeed, special or ordinary.
produce the building blocks for life, and found that the elements
He begins by exploring astronomical clues. We orbit a star that is
often referred to as “average,” when, in fact, far more stars are
smaller than the Sun than are larger. We reside in a Solar System
with terrestrial planets close to the star, and jovian planets
located at larger distances. When looking at the systems of
Bays Mountain Astronomy Club Newsletter May 2017
involved and the necessary reactions would be quite common.
Exploring the kinds of conditions necessary for life to exist, he
looked not just at the more typical kinds of life found on Earth,
but also the extremophiles that reside in some of the harshest
environments our planet can dish out. So, while life is very
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The cover for “The
Copernicus Complex”
by Caleb Scharf
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Bays Mountain Astronomy Club Newsletter May 2017
abundant on Earth, there is definitely a sampling bias. We live on
a planet inhabited by life forms, so, of course, there will be lots of
life here. Is life on Earth even representative of life that could
evolve on other planets in different circumstances? There are
many unknowns when we enter this realm.
Finally, Scharf invokes probability theory to explore the likelihood
of various conditions, both astronomical and biological, to see
whether we are unique or not. Without giving too much away, the
final answer is both yes and no. In some ways we appear to be
quite unique, while in others we are not. That may not be the
most satisfying answer, but it is the most reasonable. There are
aspects to where and when we live in the Universe that are quite
common, while other parts are quite unusual. Having life may not
be that unusual, but evolving to our level of intelligence and
technology may end up being rare.
If you are interested in a book that explores these kinds of
philosophical questions, while reviewing some of what we know
about astronomy, biology, and statistics, “The Copernicus
Complex” may just be the book for you.
Reference:
The Copernicus Complex: Our Cosmic Significance in a Universe
of Planets and Probabilities” by Caleb Scharf; Scientific
American; 2014
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Bays Mountain Astronomy Club Newsletter May 2017
Chapter 5
Space Place
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Ethan Siegel
NOAA’s Joint Polar Satellite System (JPSS) to
Monitor Earth as Never Before
Later this year, an ambitious new Earth-monitoring satellite will
temperature in over 1,000 infrared spectral channels. It will
launch into a polar orbit around our planet. The new satellite—
enable accurate weather forecasting up to seven days in
called JPSS-1—is a collaboration between NASA and NOAA. It is
advance of any major weather events.
part of a mission called the Joint Polar Satellite System, or JPSS.
• The Advanced Technology Microwave Sounder (ATMS) adds 22
At a destination altitude of only 824 km, it will complete an orbit
microwave channels to CrIS’s measurements, improving
around Earth in just 101 minutes, collecting extraordinarily high-
temperature and moisture readings.
resolution imagery of our surface, oceans and atmosphere. It will
obtain full-planet coverage every 12 hours using five separate,
independent instruments. This approach enables nearcontinuous monitoring of a huge variety of weather and climate
phenomena.
JPSS-1 will improve the prediction of severe weather events and
will help advance early warning systems. It will also be
indispensable for long-term climate monitoring, as it will track
global rainfall, drought conditions and ocean properties.
The five independent instruments on board are the main assets
of this mission:
• The Cross-track Infrared Sounder (CrIS) will detail the
atmosphere’s 3D structure, measuring water vapor and
Bays Mountain Astronomy Club Newsletter May 2017
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• Taking visible and infrared images of Earth’s surface at 750
meter resolution, the Visible Infrared Imaging Radiometer Suite
(VIIRS) instrument will enable monitoring of weather patterns,
fires, sea temperatures, light pollution, and ocean color
observations at unprecedented resolutions.
• The Ozone Mapping and Profiler Suite (OMPS) will measure
how ozone concentration varies with altitude and in time over
every location on Earth’s surface. This can help us understand
how UV light penetrates the various layers of Earth’s
atmosphere.
• The Clouds and the Earth’s Radiant System (CERES)
instrument will quantify the effect of clouds on Earth’s energy
balance, measuring solar reflectance and Earth’s radiance. It
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Bays Mountain Astronomy Club Newsletter May 2017
will greatly reduce one of the largest sources of uncertainty in
climate modeling.
The information from this satellite will be important for emergency
responders, airline pilots, cargo ships, farmers and coastal
residents, and many others. Long and short term weather
monitoring will be greatly enhanced by JPSS-1 and the rest of the
upcoming satellites in the JPSS system.
Want to teach kids about polar and geostationary orbits? Go to
the NASA Space Place: https://spaceplace.nasa.gov/geo-orbits/
This article is provided by NASA Space Place. With articles,
activities, crafts, games, and lesson plans, NASA Space Place
encourages everyone to get excited about science and
technology. Visit spaceplace.nasa.gov to explore space and Earth
science!
Caption: Ball and Raytheon technicians integrate the VIIRS
Optical and Electrical Modules onto the JPSS-1 spacecraft in
2015. The spacecraft will be ready for launch later this year.
Image Credit: Ball Aerospace & Technologies Corp.
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Bays Mountain Astronomy Club Newsletter May 2017
Chapter 6
BMAC
Calendar
and more
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BMAC Calendar and more
Date
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Time
Location
Notes
Friday, May 5, 2017
7 p.m.
Nature Center
Discovery Theater
Program: Some of the astronomy students at Sullivan South High School will join their educator, Tom Rutherford,
and speak about their continuing astronomy research. Topics include the rotational period of an asteroid, the
effects of x-rays on seeds, a high-altitude balloon launch, and an exoplanet transit.; Free.
Friday, June 2, 2017
7 p.m.
Nature Center
Discovery Theater
Program: Topic TBA; Free.
Friday, August 4, 2017
7 p.m.
Nature Center
Discovery Theater
Program: Topic TBA; Free.
3-3:30 p.m.
if clear
At the dam
View the Sun safely with a white-light view if clear.; Free.
Observatory
View the night sky with large telescopes. If poor weather, an alternate live tour of the night sky will be held in the
planetarium theater.; Free.
Saturday, April 29, 2017
1-4:30 p.m.
8:30-10
p.m.
Nature Center
& Observatory
Annual Astronomy Day - Displays et al. on the walkway leading to the Nature Center, 1-4:30 p.m.; Solar viewing
3-4 p.m. at the dam; Night viewing 8:30-10 p.m. at the observatory. All non-planetarium astronomy activities are
free.
July ?, 2017
6 p.m.
?
Annual club picnic. BMACers and their families are most welcome to enjoy the evening along with a potluck
dinner. Please bring a dish to share. You’ll need to bring your own chair and telescope to share the night sky.
BMAC Meetings
SunWatch
Every Saturday & Sunday
March - October
StarWatch
Mar. 4, 11, 2017
7:00 p.m.
Mar. 18, 25, 2017
8:00 p.m.
Apr. 1, 8, 15, 22, 29, 2017
8:30 p.m.
Special Events
Bays Mountain Astronomy Club Newsletter May 2017
36
Bays Mountain Astronomy Club
853 Bays Mountain Park Road
Kingsport, TN 37650
1 (423) 229-9447
www.baysmountain.com
Regular Contributors:
Brandon Stroupe
Brandon is the current chair of the club. He
is a photographer for his home business,
Broader Horizons Photography and an avid
astrophotographer. He has been a member
since 2007.
[email protected]
Robin Byrne
Annual Dues:
Dues are supplemented by the Bays Mountain Park
Association and volunteerism by the club. As such, our
dues can be kept at a very low cost.
$16 /person/year
$6 /additional family member
Note: if you are a Park Association member (which incurs
an additional fee), then a 50% reduction in BMAC dues
are applied.
The club’s website can be found here:
www.baysmountain.com/astronomy/astronomy-club/
Bays Mountain Astronomy Club Newsletter May 2017
Robin has been writing the science history
column since 1992 and was chair in 1997.
She is an Associate Professor of
Astronomy & Physics at Northeast State
Community College (NSCC).
Jason Dorfman
Jason works as a planetarium creative and
technical genius at Bays Mountain Park.
He has been a member since 2006.
Adam Thanz
Adam has been the Editor for all but a
number of months since 1992. He is the
Planetarium Director at Bays Mountain
Park as well as an astronomy adjunct for
NSCC.
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Section 3
Footnotes
Footnotes:
1. The Rite of Spring
Of the countless equinoxes Saturn has seen since the birth of the solar system, this one, captured
here in a mosaic of light and dark, is the first witnessed up close by an emissary from Earth …
none other than our faithful robotic explorer, Cassini.
Seen from our planet, the view of Saturn’s rings during equinox is extremely foreshortened and
limited. But in orbit around Saturn, Cassini had no such problems. From 20 degrees above the
ring plane, Cassini’s wide angle camera shot 75 exposures in succession for this mosaic showing
Saturn, its rings, and a few of its moons a day and a half after exact Saturn equinox, when the
sun’s disk was exactly overhead at the planet’s equator.
The novel illumination geometry that accompanies equinox lowers the sun’s angle to the ring
plane, significantly darkens the rings, and causes out-of-plane structures to look anomalously
bright and to cast shadows across the rings. These scenes are possible only during the few
months before and after Saturn’s equinox which occurs only once in about 15 Earth years. Before
and after equinox, Cassini’s cameras have spotted not only the predictable shadows of some of
Saturn’s moons (see PIA11657), but also the shadows of newly revealed vertical structures in the
rings themselves (see PIA11665).
Also at equinox, the shadows of the planet’s expansive rings are compressed into a single, narrow
band cast onto the planet as seen in this mosaic. (For an earlier view of the rings’ wide shadows
draped high on the northern hemisphere, see PIA09793.)
The images comprising the mosaic, taken over about eight hours, were extensively processed
before being joined together. First, each was re-projected into the same viewing geometry and
then digitally processed to make the image “joints” seamless and to remove lens flares, radially
extended bright artifacts resulting from light being scattered within the camera optics.
At this time so close to equinox, illumination of the rings by sunlight reflected off the planet vastly
dominates any meager sunlight falling on the rings. Hence, the half of the rings on the left
illuminated by planetshine is, before processing, much brighter than the half of the rings on the
right. On the right, it is only the vertically extended parts of the rings that catch any substantial
sunlight.
With no enhancement, the rings would be essentially invisible in this mosaic. To improve their
visibility, the dark (right) half of the rings has been brightened relative to the brighter (left) half by a
factor of three, and then the whole ring system has been brightened by a factor of 20 relative to
the planet. So the dark half of the rings is 60 times brighter, and the bright half 20 times brighter,
than they would have appeared if the entire system, planet included, could have been captured in
a single image.
The moon Janus (179 kilometers, 111 miles across) is on the lower left of this image. Epimetheus
(113 kilometers, 70 miles across) appears near the middle bottom. Pandora (81 kilometers, 50
Bays Mountain Astronomy Club Newsletter May 2017
More on
this image.
See FN3
miles across) orbits outside the rings on the right of the image. The small moon Atlas (30
kilometers, 19 miles across) orbits inside the thin F ring on the right of the image. The
brightnesses of all the moons, relative to the planet, have been enhanced between 30 and 60
times to make them more easily visible. Other bright specks are background stars. Spokes -ghostly radial markings on the B ring -- are visible on the right of the image.
This view looks toward the northern side of the rings from about 20 degrees above the ring plane.
The images were taken on Aug. 12, 2009, beginning about 1.25 days after exact equinox, using
the red, green and blue spectral filters of the wide angle camera and were combined to create this
natural color view. The images were obtained at a distance of approximately 847,000 kilometers
(526,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 74 degrees.
Image scale is 50 kilometers (31 miles) per pixel.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and
the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of
Technology in Pasadena, manages the mission for NASA's Science Mission Directorate,
Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed
and assembled at JPL. The imaging operations center is based at the Space Science Institute in
Boulder, Colo.
For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov/. The
Cassini imaging team homepage is at http://ciclops.org.
Image Credit: NASA/JPL/Space Science Institute
2. Duke on the Craters Edge
Astronaut Charles M. Duke Jr., Lunar Module pilot of the Apollo 16 mission, is photographed
collecting lunar samples at Station no. 1 during the first Apollo 16 extravehicular activity at the
Descartes landing site. This picture, looking eastward, was taken by Astronaut John W. Young,
commander. Duke is standing at the rim of Plum crater, which is 40 meters in diameter and 10
meters deep. The parked Lunar Roving Vehicle can be seen in the left background.
Image AS16-114-18423
Creator/Photographer: NASA John W. Young
3. The Cat's Eye Nebula, one of the first planetary nebulae discovered, also has one of the most
complex forms known to this kind of nebula. Eleven rings, or shells, of gas make up the Cat's Eye.
Credit: NASA, ESA, HEIC, and The Hubble Heritage Team (STScI/AURA)
Acknowledgment: R. Corradi (Isaac Newton Group of Telescopes, Spain) and Z. Tsvetanov (NASA)
4. Jupiter & Ganymede
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NASA's Hubble Space Telescope has caught Jupiter's moon Ganymede playing a game of "peeka-boo." In this crisp Hubble image, Ganymede is shown just before it ducks behind the giant
planet.
Ganymede completes an orbit around Jupiter every seven days. Because Ganymede's orbit is
tilted nearly edge-on to Earth, it routinely can be seen passing in front of and disappearing behind
its giant host, only to reemerge later.
Composed of rock and ice, Ganymede is the largest moon in our solar system. It is even larger
than the planet Mercury. But Ganymede looks like a dirty snowball next to Jupiter, the largest
planet in our solar system. Jupiter is so big that only part of its Southern Hemisphere can be seen
in this image.
Hubble's view is so sharp that astronomers can see features on Ganymede's surface, most
notably the white impact crater, Tros, and its system of rays, bright streaks of material blasted from
the crater. Tros and its ray system are roughly the width of Arizona.
The image also shows Jupiter's Great Red Spot, the large eye-shaped feature at upper left. A
storm the size of two Earths, the Great Red Spot has been raging for more than 300 years.
Hubble's sharp view of the gas giant planet also reveals the texture of the clouds in the Jovian
atmosphere as well as various other storms and vortices.
Astronomers use these images to study Jupiter's upper atmosphere. As Ganymede passes behind
the giant planet, it reflects sunlight, which then passes through Jupiter's atmosphere. Imprinted on
that light is information about the gas giant's atmosphere, which yields clues about the properties
of Jupiter's high-altitude haze above the cloud tops.
This color image was made from three images taken on April 9, 2007, with the Wide Field Planetary
Camera 2 in red, green, and blue filters. The image shows Jupiter and Ganymede in close to
natural colors.
Credit: NASA, ESA, and E. Karkoschka (University of Arizona)
5. 47 Tucanae
In the first attempt to systematically search for "extrasolar" planets far beyond our local stellar
neighborhood, astronomers probed the heart of a distant globular star cluster and were surprised
to come up with a score of "zero".
To the fascination and puzzlement of planet-searching astronomers, the results offer a sobering
counterpoint to the flurry of planet discoveries announced over the previous months.
"This could be the first tantalizing evidence that conditions for planet formation and evolution may
be fundamentally different elsewhere in the galaxy," says Mario Livio of the Space Telescope
Science Institute (STScI) in Baltimore, MD.
The bold and innovative observation pushed NASA Hubble Space Telescope's capabilities to its
limits, simultaneously scanning for small changes in the light from 35,000 stars in the globular star
cluster 47 Tucanae, located 15,000 light-years (4 kiloparsecs) away in the southern constellation
Tucana.
Hubble researchers caution that the finding must be tempered by the fact that some astronomers
always considered the ancient globular cluster an unlikely abode for planets for a variety of
reasons. Specifically, the cluster has a deficiency of heavier elements that may be needed for
building planets. If this is the case, then planets may have formed later in the universe's evolution,
when stars were richer in heavier elements. Correspondingly, life as we know it may have appeared
later rather than sooner in the universe.
Another caveat is that Hubble searched for a specific type of planet called a "hot Jupiter," which is
considered an oddball among some planet experts. The results do not rule out the possibility that
47 Tucanae could contain normal solar systems like ours, which Hubble could not have detected.
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But even if that's the case, the "null" result implies there is still something fundamentally different
between the way planets are made in our own neighborhood and how they are made in the cluster.
Hubble couldn't directly view the planets, but instead employed a powerful search technique
where the telescope measures the slight dimming of a star due to the passage of a planet in front
of it, an event called a transit. The planet would have to be a bit larger than Jupiter to block
enough light — about one percent — to be measurable by Hubble; Earth-like planets are too small.
However, an outside observer would have to watch our Sun for as long as 12 years before ever
having a chance of seeing Jupiter briefly transit the Sun's face. The Hubble observation was
capable of only catching those planetary transits that happen every few days. This would happen if
the planet were in an orbit less than 1/20 Earth's distance from the Sun, placing it even closer to
the star than the scorched planet Mercury — hence the name "hot Jupiter."
Why expect to find such a weird planet in the first place?
Based on radial-velocity surveys from ground-based telescopes, which measure the slight wobble
in a star due to the small tug of an unseen companion, astronomers have found nine hot Jupiters
in our local stellar neighborhood. Statistically this means one percent of all stars should have such
planets. It's estimated that the orbits of 10 percent of these planets are tilted edge-on to Earth and
so transit the face of their star.
In 1999, the first observation of a transiting planet was made by ground-based telescopes. The
planet, with a 3.5-day period, had previously been detected by radial-velocity surveys, but this was
a unique, independent confirmation. In a separate program to study a planet in these revealing
circumstances, Ron Gilliland (STScI) and lead investigator Tim Brown (National Center for
Atmospheric Research, Boulder, CO) demonstrated Hubble's exquisite ability to do precise
photometry — the measurement of brightness and brightness changes in a star's light — by also
looking at the planet. The Hubble data were so good they could look for evidence of rings or Earthsized moons, if they existed.
But to discover new planets by transits, Gilliland had to crowd a lot of stars into Hubble's narrow
field of view. The ideal target was the magnificent southern globular star cluster 47 Tucanae, one of
the closest clusters to Earth. Within a single Hubble picture Gilliland could observe 35,000 stars at
once. Like making a time-lapse movie, he had to take sequential snapshots of the cluster, looking
for a telltale dimming of a star and recording any light curve that would be the true signature of a
planet.
Based on statistics from a sampling of planets in our local stellar neighborhood, Gilliland and his
co-investigators reasoned that 1 out of 1,000 stars in the globular cluster should have planets that
transit once every few days. They predicted that Hubble should discover 17 hot Jupiter-class
planets.
To catch a planet in a several-day orbit, Gilliland had Hubble's "eagle eye" trained on the cluster
for eight consecutive days. The result was the most data-intensive observation ever done by
Hubble. STScI archived over 1,300 exposures during the observation. Gilliland and Brown sifted
through the results and came up with 100 variable stars, some of them eclipsing binaries where the
companion is a star and not a planet. But none of them had the characteristic light curve that
would be the signature of an extrasolar planet.
There are a variety of reasons the globular cluster environment may inhibit planet formation. 47
Tucanae is old and so is deficient in the heavier elements, which were formed later in the universe
through the nucleosynthesis of heavier elements in the cores of first-generation stars. Planet
surveys show that within 100 light-years of the Sun, heavy-element-rich stars are far more likely to
harbor a hot Jupiter than heavy-element-poor stars. However, this is a chicken and egg puzzle
because some theoreticians say that the heavy-element composition of a star may be enhanced
after if it makes Jupiter-like planets and then swallows them as the planet orbit spirals into the star.
Bays Mountain Astronomy Club Newsletter May 2017
The stars are so tightly compacted in the core of the cluster – being separated by 1/100th the
distance between our Sun and the next nearest star — that gravitational tidal effects may strip
nascent planets from their parent stars. Also, the high stellar density could disturb the subsequent
migration of the planet inward, which parks the hot Jupiters close to the star.
Another possibility is that a torrent of ultraviolet light from the earliest and biggest stars, which
formed in the cluster billions of years ago may have boiled away fragile embryonic dust disks out
of which planets would have formed.
These results will be published in The Astrophysical Journal Letters in December. Follow-up
observations are needed to determine whether it is the initial conditions associated with planet
birth or subsequent influences on evolution in this heavy-element-poor, crowded environment that
led to an absence of planets.
Credits for Hubble image: NASA and Ron Gilliland (Space Telescope Science Institute)
6. Space Place is a fantastic source of scientific educational materials for children of all ages. Visit
them at:
http://spaceplace.nasa.gov
7. NGC 3982
Though the universe is chock full of spiral-shaped galaxies, no two look exactly the same. This
face-on spiral galaxy, called NGC 3982, is striking for its rich tapestry of star birth, along with its
winding arms. The arms are lined with pink star-forming regions of glowing hydrogen, newborn
blue star clusters, and obscuring dust lanes that provide the raw material for future generations of
stars. The bright nucleus is home to an older population of stars, which grow ever more densely
packed toward the center.
NGC 3982 is located about 68 million light-years away in the constellation Ursa Major. The galaxy
spans about 30,000 light-years, one-third of the size of our Milky Way galaxy. This color image is
composed of exposures taken by the Hubble Space Telescope's Wide Field Planetary Camera 2
(WFPC2), the Advanced Camera for Surveys (ACS), and the Wide Field Camera 3 (WFC3). The
observations were taken between March 2000 and August 2009. The rich color range comes from
the fact that the galaxy was photographed invisible and near-infrared light. Also used was a filter
that isolates hydrogen emission that emanates from bright star-forming regions dotting the spiral
arms.
Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
Acknowledgment: A. Riess (STScI)
8. Ball and Raytheon technicians integrate the VIIRS Optical and Electrical Modules onto the
JPSS-1 spacecraft in 2015. The spacecraft will be ready for launch later this year. Image Credit:
Ball Aerospace & Technologies Corp.
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Bays Mountain Astronomy Club Newsletter May 2017