March 2018 March the Monthly Newsletter of the Bays Mountain Astronomy Club

March 2018 March The Monthly Newsletter of the Bays Mountain Astronomy Club

More on Edited by Adam Thanz this image. See FN1 Chapter 1 Looking Up

Brandon Stroupe - BMAC Chair

More on this image. See FN2 Brandon Stroupe

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Hello BMACers, how we perceive what we actually see in an esoteric sense. I believe Dan will be giving us a very informative and enjoyable Here we are in March already. The months are moving right along talk. I hope everyone will be able to come out and participate in and the weather is completely unpredictable. Have I mentioned our meeting. in the past how much that I do not like the weather here in Tennessee? Of course, I have. It is getting closer and closer to At our February meeting, our topic of discussion was eyepieces. warmer weather which probably makes many of you happier. It We spoke about the various types of eyepieces and what objects makes me just a little sad. You all know I like the cooler weather. in the night sky that they would be used for. We spoke briefly It is much better weather to image with a DSLR. And the about the different optics in the eyepieces as well as the humidity is much lower in cooler weather. I hate that hot, sticky materials they are made from. We also spoke about the different feeling. Okay, I am done talking about the weather and how types of filters that are used with different eyepieces and what much I do not like it. they are good for. There were different types of eyepieces, a Barlow lens, and filters to look at. This was an open format For our March meeting, we will be given a presentation by one of presentation, which was a good thing since I am not very our very own members. Dan Mullen will be giving his knowledgeable about eyepieces. We had a lot of people give presentation entitled, “From Reality to Perception.” For those their opinions and knowledge about eyepieces. Even I learned a whose passion is visual astronomy, we may take for granted the lot. Again, I really like these types of presentations because it view through our telescopes of our favorite objects. However, it gets the audience involved and many of you have a lot to offer in is quite a feat that our instruments can deliver such images the field of amateur astronomy. I want to thank everyone that taking in consideration the obstacles or “filters” through which came out and participated in the meeting and I hope to see you the light path travels. Our discussion will be on the effect of all at the next meeting. these “filters” on our viewing sessions, and taking a step further,

Bays Mountain Astronomy Club Newsletter March 2018 3 Lynx Image from Stellarium annotations by Adam Thanz

4 Bays Mountain Astronomy Club Newsletter March 2018 Sculpture of Hevelius in Gdańsk, Poland. Image by Adam Thanz

5 Bays Mountain Astronomy Club Newsletter March 2018 Our constellation this month will be Lynx. As you may have because Wayne Manly, who typically runs them, may not be able guessed it, it is named after the animal. This constellation does to be available as much this year. As mentioned in the meeting not have any mythology behind it that I could find. This last month, to volunteer to help run the scopes at Bays Mountain, constellation was formed by the Polish astronomer Johannes you will need to be trained and authorized. You can contact Adam Hevelius in 1687 from 19 faint stars between the constellations Thanz or Jason Dorfman if you are interested. Please don't let Ursa Major and Auriga. He named it Lynx because of its faintness that stop you from volunteering though. It should be a quick and and he challenged future stargazers to spot it. He claims that only easy process to complete. It will be worth the effort for the public. the lynx-eyed, which would be those with good eye sight, would Just remember how fun it is to see a kid’s, and even some grown- be able to recognize it. As for deep-sky objects in this up’s, reactions when looking through a telescope for the first time constellation, there is a globular cluster, some galaxies, and even or seeing Saturn’s rings or Jupiter’s moons for the first time. It a supercluster. The globular cluster NGC 2419 known as the never gets old sparking an interest in astronomy to someone of “Intergalactic Wanderer” is the most notable in this constellation. any age. Until next month… Clear Skies. NGC 2537 is a dwarf galaxy in Lynx along with the NGC 2841 group, which is a group of galaxies lying among this constellation and Ursa Major. The Lynx Supercluster is a remote supercluster. It was the most distant supercluster known at the time of its discovery in 1999. It is made up of 2 main clusters of galaxies and other smaller clumps. I did not know much about this constellation until I wrote this article. It has plenty of objects to look at the next time you are out under the stars. If you would like to know more, check out Jason Dorfman’s article, “Celestial Happenings.”

That will be it for this month. Please remember that the StarWatches and the SunWatches will start again this month. I hope everyone will be able to make plans to help with them if possible. We will deﬁnitely need some help with the SunWatches

6 Bays Mountain Astronomy Club Newsletter March 2018 Chapter 2 BMAC Notes

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Tennessee Spring Star Party 2018 There will be vendors set up in the lobby at the inn as well as a The Astronomy in the Parks Society, Cumberland Astronomical swap table. Society, Dyer Observatory and Fall Creek Falls State Park will be We will also offer an introduction to astronomy on Saturday night hosting the annual Tennessee Spring Star Party 2018 on March on the observation field, showing those interested how to use a 16-18, 2018 at Fall Creek Falls State Park in Pikeville, Tennessee. star wheel and telescope. As in the past, TSSP 2018 is free to attend and registration is not Come enjoy a weekend under the stars at one of Tennessee's required. All are welcome to attend and are responsible for their premier parks. Fall Creek Falls has a family friendly atmosphere own food and lodging. Fall Creek Falls is offering a star party with activities offered for all ages. package for those wishing to stay at the inn. Campsites are also available. Call 1-800-250-8610 for reservations. Ask for the star http://tn.gov/environment/parks/FallCreekFalls/ party package for rooms at the inn. For more information, contact: Lloyd Watkins There will be all night observing Friday and Saturday night on the [email protected]; Allen Ball [email protected] observing field (observers are permitted to nap in their vehicles, but camping on the observing field is not permitted). We will have a hospitality/warming tent on the observing field with warm beverages and snacks provided. There will be public viewing Friday and Saturday nights, 7-10 p.m.

During the day on Saturday there will be free programs oﬀered in the Cascade Room. The speakers are being ﬁnalized at this time.

Bays Mountain Astronomy Club Newsletter March 2018 8 Chapter 3 Celestial Happenings

Jason Dorfman

More on this image. See FN5 Jason Dorfman

More on Celestial Happenings this image. See FN3

The month of March begins and ends with a full moon. This will 1.1° to the right of Venus. Both will appear nearly full. Venus will be the second “blue moon” of the year - the first was in January. show about a 10” diameter disk with Mercury about half that at The vernal equinox occurs on the 20th, this is the official start of 5.6” and showing 87% illumination. As the month continues on, Spring, though as I write this in February we are having lovely the two begin to climb out of the twilight glow. Swift Mercury 70° weather. Also this month, don’t forget the time change to climbs higher initially, reaching its peak and greatest elongation Daylight Saving Time on Sunday, March 11. Set your clocks on the 15th. A half hour after sunset on that day, it will be about forward an hour on this day. 12° above the horizon and 6° high a half hour later when the sky is a bit darker. At its greatest elongation, the magnitude of Mercury will have dropped to -0.4 and the illumination to about Planets half, but the disk will have grown to 7.3”. After this day, Mercury begins its swift plunge back into the bright twilight of the setting For those who have been missing the opportunity to view the Sun. Be sure to look again on the 18th to catch a thin crescent planets in the evening sky, your wait is finally over. As March Moon to the left of Venus and Mercury. The Moon will be about begins, look low towards the western horizon in the early twilight 4° from Venus with Mercury about the same distance away to the hour. First, you’ll find Venus and then look harder for Mercury. On right of Venus. The trio will be about 10° above the horizon a half the 1st, Venus will be about 5° above the horizon a half hour after hour after sunset. sunset with Mercury about 1.8° to the lower right. At magnitude -3.9, Venus will easily penetrate the bright evening twilight. Faint Neptune is now gone from our evening skies and will be in Mercury, however, may be more challenging for the naked eye at conjunction with the Sun on the 4th. Uranus is still visible as the magnitude -1.3. With binoculars, locate Venus first and then month begins. It will be about 25° above the western horizon an Mercury. On the 3rd, the two will be a bit closer with Mercury hour after sunset at the end of the first week and 20° after the

Bays Mountain Astronomy Club Newsletter March 2018 10 second week. On the 28th, Uranus will appear just 4’ from Venus, Mars will be 0.9° to the west of this wonderful 5th-magnitude the closest that the two have been since this same date in 2003. globular cluster and just 1.7° to the lower right of Saturn. Mars At 6th magnitude, though, you may have difficultly pulling Uranus and Saturn will rise together on this day just before 3 a.m. from the evening twilight. This is your last opportunity to glimpse Both Mars and Saturn reach west quadrature (when they are 90° this distant ice giant before it transitions into our morning skies, west of the Sun) this month - Mars on the 24th and Saturn on the next month. 29th. This position with respect to the Earth provides some Rising just before midnight is Jupiter, your next planet to observe. unique observational effects. Mars will appear gibbous with a It starts the month at magnitude -2.2 with a disk diameter of 39” shadowed edge highlighting that, though it’s a more distant and ends it at magnitude -2.4 and a slightly larger disk of 43”. planet from the Sun, it does exhibit a slight phase effect. With Currently among the background stars of Libra, best observations Saturn, the shadows of the planet and rings will extend the will occur in the pre-dawn hours when the planet climbs higher in farthest to the side, providing a more 3-dimensional view to the the south. “Ringed World.”

The Red Planet rises a few hours later at about 2:30 a.m. On the Saturn has a much slower movement eastward with its greater first, its magnitude will be +0.8 and the disk will span 6.7”. By the distance from the Sun and so will remain roughly above the end of the month, the disk will have grown to 8.4” and Mars will Teapot in Sagittarius throughout the month. In fact, it will be have brightened to magnitude +0.3. Mars makes a good trek about 2° from M22 all month long - creating a nice pairing without eastward of about 20° this month moving through the heart of the Mars in the field for most of the month. The rings of Saturn span Milky Way from the lower part of Ophiuchus into Sagittarius. This about 37” during March and are tilted 26° to us. The magnitude of provides some great observational opportunities, as well as Saturn is +0.5 for the month. unique astrophotography pairings, as Mars moves past some wonderful deep sky objects. Mars crosses into Sagittarius on the 12th. On the 19th, it will be midway between M8 and M20, the Luna Lagoon and Trifid nebulae, respectively. Next is M28 on the 28th, Mars will pass 1.3° north of this globular cluster. Mars ends the Once again this year, we will have two full Moons, one on the 1st month spectacularly with a close grouping with Saturn and M22. and another on the 31st. In addition to the alignment with Venus and Mercury on the 18th, the Moon swings past Jupiter, Mars and

11 Bays Mountain Astronomy Club Newsletter March 2018 Saturn earlier in the month, just as it did last month. On the 7th, a The constellation for March is Lynx and is definitely one of the small waning gibbous Moon will be about 3-4° to the upper left of more challenging to find in the sky. The brightest star, ! Lyn, is Jupiter. Then from the 9th to the 11th, as the Moon progresses magnitude +3.1 and the remaining stars that define the shape of from 3rd quarter to a waning crescent, it will glide past Mars and the Lynx are all between this and magnitude +4.6, which makes then Saturn. this a tough one to see around much of the Tri-Cities area. To find this constellation during March, look high overhead and just north of zenith. Lynx runs like a squiggly line from the southeast next to Meteor Showers? Leo Minor up towards Camelopardalis in the northwest passing between Ursa Major and Gemini. There are roughly eight bright There are no notable showers for our latitude this month, stars that define the shape of this wild cat. however, we do have the opportunity to observe a feature related to the occurrence of meteors, the zodiacal light. When we are The constellation was not from Ptolemy, but came years later observing meteors streaking across the sky from a meteor from Johannes Hevelius. There are a baker’s dozen of galaxies shower, we are typically seeing comet dust burn up in our located in Lynx but, all are quite faint at 12th and 13th magnitude atmosphere. This debris is left over from the passage of a comet and there are no Messier objects. One object of interest, NGC through the inner part of the Solar System. Though not all comets 2419, is the most distant globular cluster in the Milky Way. It is take a path that is aligned with the Ecliptic, much of the comet located nearly opposite the galactic center and is roughly 182,000 debris is concentrated along the ecliptic plane. This month, as it ly from the Sun. This distance is similar to the Magellanic Clouds does every March, the Ecliptic makes a steep angle to the and suggests that this cluster may be an independent western horizon providing an opportunity to see the pyramidal intergalactic object. It has a magnitude of roughly +11.5 and glow due to the dust. To look for this, head away from city lights spans about 2’ and can be seen as a small fuzzy spot in small and look to the west after twilight ends. The best time will be telescopes. between the 3rd and the 18th, when the Moon is not visible in the Happy Observing!! evening sky.

Constellation of the Month

12 Bays Mountain Astronomy Club Newsletter March 2018 Chapter 4 The Queen Speaks Robin Byrne Robin Byrne

More on Book Review: From a Certain Point of View this image. See FN3

I’m deviating from my traditional review of a book dealing with the Jawas; a touching story from the perspective of the red droid factual information to the realm of fiction. Why? BECAUSE IT’S with the bad motivator that was rejected by Luke’s Uncle Owen; STAR WARS! From a Certain Point of View was written to thoughts from a disgruntled Storm Trooper who would rather get celebrate the 40th anniversary of the release of Star Wars: A New a drink in the cantina than question people about droids they Hope. It is comprised of 40 short stories, each written by a aren’t even looking for; several stories from the various beings different author (or authors). While the stories follow the events of frequenting the cantina; why the bar tender really hates droids A New Hope, they are told from the perspective of characters and won’t serve their kind; who was that cloaked, long-nosed either in the background, or not even seen in the film. spy telling the Storm Troopers where to find the droids; tales from a variety of employees stationed on the Death Star; the Because each story has a different author, the styles vary widely. contents of the incident report filed after Darth Vader force That means there may be some stories you’ll love and others choked Admiral Motti; the last moments of Leia’s adoptive that bore you. That was certainly my experience. However, there parents on Alderaan; an ill-fated love affair on the Death Star as were far more that I truly enjoyed than stories I could have done seen through the eyes of a mouse droid; the experiences of without. I got the audio book to listen to while driving to and from different rebels during the Battle of Yavin; where Mon Mothma work. The audio book version has the added bonus of hearing was during the battle and how she was prepared for the worst; the stories read by a variety of people lending their voice talents and a humorous take on the opening crawl from a critic. to the characters, along with sound effects and music enhancing the stories. The stories range from heart-breaking to hilarious, and they left me wanting to watch A New Hope again with an eye only on Some of the stories you’ll encounter include: how to cover up the what’s happening in the background. And if that isn’t enough to fact that you didn’t shoot down the escape pod that you now encourage you to get the book, proceeds are donated to First realize carried the Death Star plans to Tatooine; dreams of one of

Bays Mountain Astronomy Club Newsletter March 2018 14 The cover to “From a Certain Point of View” along with the authors listed.

15 Bays Mountain Astronomy Club Newsletter March 2018 Book, which provides books to teachers and children’s organizations.

So there you have it - a combination of Star Wars, a wide range of stories, and it helps a non-proﬁt organization. What are you waiting for? Get yourself a copy of From a Certain Point of View.

References:

From a Certain Point of View: 40 Stories Celebrating 40 Years of Star Wars, various authors, Del Rey, 2017

16 Bays Mountain Astronomy Club Newsletter March 2018 Chapter 5 Space Place

More on this image. See FN6 Linda Hermans-Killiam

What Is the Ionosphere? More on this image. See FN3

High above Earth is a very active part of our upper atmosphere many of the tools we take for granted here on Earth, such as called the ionosphere. The ionosphere gets its name from ions— GPS. Radio signals also allow us to communicate with tiny charged particles that blow around in this layer of the astronauts on board the International Space Station, which orbits atmosphere. Earth within the ionosphere. Learning more about this region of our atmosphere may help us improve forecasts about when How did all those ions get there? They were made by energy these radio signals could be distorted and help keep humans from the Sun! safe. Everything in the Universe that takes up space is made up of In 2018, NASA has plans to launch two missions that will work matter, and matter is made of tiny particles called atoms. At the together to study the ionosphere. NASA’s GOLD (Global-scale ionosphere, atoms from the Earth’s atmosphere meet up with Observations of the Limb and Disk) mission launched in January energy from the Sun. This energy, called radiation, strips away 2018. GOLD will orbit 22,000 miles above Earth. From way up parts of the atom. What’s left is a positively or negatively charged there, it will be able to create a map of the ionosphere over the atom, called an ion. Americas every half hour. It will measure the temperature and The ionosphere is ﬁlled with ions. These particles move about in makeup of gases in the ionosphere. GOLD will also study a giant wind. However, conditions in the ionosphere change all bubbles of charged gas that are known to cause communication the time. Earth’s seasons and weather can cause changes in the problems. ionosphere, as well as radiation and particles from the Sun— A second NASA mission, called ICON, short for Ionospheric called space weather. Connection Explorer, will launch later in 2018. It will be placed in These changes in the ionosphere can cause problems for an orbit just 350 miles above Earth—through the ionosphere. humans. For example, they can interfere with radio signals This means it will have a close-up view of the upper atmosphere between Earth and satellites. This could make it diﬃcult to use to pair with GOLD’s wider view. ICON will study the forces that

Bays Mountain Astronomy Club Newsletter March 2018 18 More on this image. See FN8

19 Bays Mountain Astronomy Club Newsletter March 2018 shape this part of the upper atmosphere.

Both missions will study how the ionosphere is aﬀected by Earth and space weather. Together, they will give us better observations of this part of our atmosphere than we have ever had before.

To learn more about the ionosphere, check out NASA Space Place: https://spaceplace.nasa.gov/ionosphere

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!

20 Bays Mountain Astronomy Club Newsletter March 2018 Chapter 6 BMAC Calendar and more

More on this image. See FN7 More on BMAC Calendar and more this image. See FN3

Date Time Location Notes

BMAC Meetings

Program: Dan Mullen: “From Reality to Perception.” For those whose passion is visual astronomy, we may take for granted the view through our telescopes of our favorite objects. However, it is quite a feat that our Nature Center Friday, March 2, 2018 7 p.m. instruments can deliver such images taking in consideration the obstacles or “ﬁlters” through which the light path Discovery Theater travels. Our discussion will be on the effect of these “ﬁlters” on our viewing sessions, and taking a step further, how we perceive what we actually see in an esoteric sense.; Free.

Nature Center Friday, April 6, 2018 7 p.m. Program: Topic TBA; Free. Discovery Theater

Nature Center Friday, May 4, 2018 7 p.m. Program: Topic TBA; Free. Discovery Theater

SunWatch

Every Saturday & Sunday 3-3:30 p.m. At the dam View the Sun safely with a white-light view if clear.; Free. March - October if clear

StarWatch

Mar. 3, 10, 2018 7:00 p.m. View the night sky with large telescopes. If poor weather, an alternate live tour of the night sky will be held in the Mar. 17, 24, 2018 8:00 p.m. Observatory planetarium theater.; Free. Apr. 7, 14, 21, 28, 2018 8:30 p.m.

Special Events

1-4:30 p.m. Annual Astronomy Day - Displays et al. on the walkway leading to the Nature Center, 1-4:30 p.m.; Solar viewing Nature Center Saturday, April 21, 2018 8:30-10 3-3:30 p.m. at the dam; Night viewing 8:30-10 p.m. at the observatory. All non-planetarium astronomy activities & Observatory p.m. are free.

Bays Mountain Astronomy Club Newsletter March 2018 22 Bays Mountain Astronomy Club Regular Contributors:

853 Bays Mountain Park Road Brandon Stroupe

Kingsport, TN 37650 Brandon is the current chair of the club. He is a photographer for his home business, 1 (423) 229-9447 Broader Horizons Photography and an avid astrophotographer. He has been a www.baysmountain.com member since 2007. [email protected] Robin Byrne

Robin has been writing the science history column since 1992 and was chair in 1997. She is an Associate Professor of Annual Dues: Astronomy & Physics at Northeast State Community College (NSCC). 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. Jason Dorfman $16 /person/year Jason works as a planetarium creative and $6 /additional family member technical genius at Bays Mountain Park. He has been a member since 2006. Note: if you are a Park Association member (which incurs an additional fee), then a 50% reduction in BMAC dues are applied. Adam Thanz

The club’s website can be found here: Adam has been the Editor for all but a number of months since 1992. He is the www.baysmountain.com/astronomy/astronomy-club/ Planetarium Director at Bays Mountain Park as well as an astronomy adjunct for NSCC.

Bays Mountain Astronomy Club Newsletter March 2018 23 Section 3

More on Footnotes this image. See FN3

miles across) orbits outside the rings on the right of the image. The small moon Atlas (30 Footnotes: 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 1. The Rite of Spring 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. 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 This view looks toward the northern side of the rings from about 20 degrees above the ring plane. Earth … none other than our faithful robotic explorer, Cassini. The images were taken on Aug. 12, 2009, beginning about 1.25 days after exact equinox, using Seen from our planet, the view of Saturn’s rings during equinox is extremely foreshortened and the red, green and blue spectral filters of the wide angle camera and were combined to create this limited. But in orbit around Saturn, Cassini had no such problems. From 20 degrees above the natural color view. The images were obtained at a distance of approximately 847,000 kilometers ring plane, Cassini’s wide angle camera shot 75 exposures in succession for this mosaic showing (526,000 miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 74 degrees. Saturn, its rings, and a few of its moons a day and a half after exact Saturn equinox, when the Image scale is 50 kilometers (31 miles) per pixel. sun’s disk was exactly overhead at the planet’s equator. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and The novel illumination geometry that accompanies equinox lowers the sun’s angle to the ring the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of plane, significantly darkens the rings, and causes out-of-plane structures to look anomalously Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, bright and to cast shadows across the rings. These scenes are possible only during the few Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed months before and after Saturn’s equinox which occurs only once in about 15 Earth years. Before and assembled at JPL. The imaging operations center is based at the Space Science Institute in and after equinox, Cassini’s cameras have spotted not only the predictable shadows of some of Boulder, Colo. Saturn’s moons (see PIA11657), but also the shadows of newly revealed vertical structures in the For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov/. The rings themselves (see PIA11665). Cassini imaging team homepage is at http://ciclops.org. Also at equinox, the shadows of the planet’s expansive rings are compressed into a single, Image Credit: NASA/JPL/Space Science Institute 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.) 2. Duke on the Craters Edge 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 Astronaut Charles M. Duke Jr., Lunar Module pilot of the Apollo 16 mission, is photographed then digitally processed to make the image “joints” seamless and to remove lens flares, radially collecting lunar samples at Station no. 1 during the first Apollo 16 extravehicular activity at the extended bright artifacts resulting from light being scattered within the camera optics. 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 At this time so close to equinox, illumination of the rings by sunlight reflected off the planet vastly meters deep. The parked Lunar Roving Vehicle can be seen in the left background. 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 Image AS16-114-18423 right. On the right, it is only the vertically extended parts of the rings that catch any substantial Creator/Photographer: NASA John W. Young sunlight. With no enhancement, the rings would be essentially invisible in this mosaic. To improve their 3. The Cat's Eye Nebula, one of the first planetary nebulae discovered, also has one of the most visibility, the dark (right) half of the rings has been brightened relative to the brighter (left) half by a complex forms known to this kind of nebula. Eleven rings, or shells, of gas make up the Cat's factor of three, and then the whole ring system has been brightened by a factor of 20 relative to Eye. 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 Credit: NASA, ESA, HEIC, and The Hubble Heritage Team (STScI/AURA) a single image. Acknowledgment: R. Corradi (Isaac Newton Group of Telescopes, Spain) and Z. Tsvetanov The moon Janus (179 kilometers, 111 miles across) is on the lower left of this image. Epimetheus (NASA) (113 kilometers, 70 miles across) appears near the middle bottom. Pandora (81 kilometers, 50

Bays Mountain Astronomy Club Newsletter March 2018 24 4. Jupiter & Ganymede Another caveat is that Hubble searched for a specific type of planet called a "hot Jupiter," which is NASA's Hubble Space Telescope has caught Jupiter's moon Ganymede playing a game of "peek- considered an oddball among some planet experts. The results do not rule out the possibility that a-boo." In this crisp Hubble image, Ganymede is shown just before it ducks behind the giant 47 Tucanae could contain normal solar systems like ours, which Hubble could not have detected. planet. 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. 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 Hubble couldn't directly view the planets, but instead employed a powerful search technique its giant host, only to reemerge later. 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 Composed of rock and ice, Ganymede is the largest moon in our solar system. It is even larger enough light — about one percent — to be measurable by Hubble; Earth-like planets are too small. 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 However, an outside observer would have to watch our Sun for as long as 12 years before ever in this image. 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 Hubble's view is so sharp that astronomers can see features on Ganymede's surface, most the planet were in an orbit less than 1/20 Earth's distance from the Sun, placing it even closer to notably the white impact crater, Tros, and its system of rays, bright streaks of material blasted from the star than the scorched planet Mercury — hence the name "hot Jupiter." the crater. Tros and its ray system are roughly the width of Arizona. Why expect to find such a weird planet in the first place? 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. Based on radial-velocity surveys from ground-based telescopes, which measure the slight wobble Hubble's sharp view of the gas giant planet also reveals the texture of the clouds in the Jovian in a star due to the small tug of an unseen companion, astronomers have found nine hot Jupiters atmosphere as well as various other storms and vortices. 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 Astronomers use these images to study Jupiter's upper atmosphere. As Ganymede passes behind so transit the face of their star. 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 In 1999, the first observation of a transiting planet was made by ground-based telescopes. The of Jupiter's high-altitude haze above the cloud tops. 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 This color image was made from three images taken on April 9, 2007, with the Wide Field Planetary circumstances, Ron Gilliland (STScI) and lead investigator Tim Brown (National Center for Camera 2 in red, green, and blue filters. The image shows Jupiter and Ganymede in close to Atmospheric Research, Boulder, CO) demonstrated Hubble's exquisite ability to do precise natural colors. photometry — the measurement of brightness and brightness changes in a star's light — by also Credit: NASA, ESA, and E. Karkoschka (University of Arizona) looking at the planet. The Hubble data were so good they could look for evidence of rings or Earth- sized moons, if they existed. 5. 47 Tucanae 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 In the first attempt to systematically search for "extrasolar" planets far beyond our local stellar the closest clusters to Earth. Within a single Hubble picture Gilliland could observe 35,000 stars at neighborhood, astronomers probed the heart of a distant globular star cluster and were surprised once. Like making a time-lapse movie, he had to take sequential snapshots of the cluster, looking to come up with a score of "zero". for a telltale dimming of a star and recording any light curve that would be the true signature of a To the fascination and puzzlement of planet-searching astronomers, the results offer a sobering planet. counterpoint to the flurry of planet discoveries announced over the previous months. Based on statistics from a sampling of planets in our local stellar neighborhood, Gilliland and his "This could be the first tantalizing evidence that conditions for planet formation and evolution may co-investigators reasoned that 1 out of 1,000 stars in the globular cluster should have planets that be fundamentally different elsewhere in the galaxy," says Mario Livio of the Space Telescope transit once every few days. They predicted that Hubble should discover 17 hot Jupiter-class Science Institute (STScI) in Baltimore, MD. planets. The bold and innovative observation pushed NASA Hubble Space Telescope's capabilities to its To catch a planet in a several-day orbit, Gilliland had Hubble's "eagle eye" trained on the cluster limits, simultaneously scanning for small changes in the light from 35,000 stars in the globular star for eight consecutive days. The result was the most data-intensive observation ever done by cluster 47 Tucanae, located 15,000 light-years (4 kiloparsecs) away in the southern constellation Hubble. STScI archived over 1,300 exposures during the observation. Gilliland and Brown sifted Tucana. through the results and came up with 100 variable stars, some of them eclipsing binaries where the Hubble researchers caution that the finding must be tempered by the fact that some astronomers companion is a star and not a planet. But none of them had the characteristic light curve that always considered the ancient globular cluster an unlikely abode for planets for a variety of would be the signature of an extrasolar planet. reasons. Specifically, the cluster has a deficiency of heavier elements that may be needed for There are a variety of reasons the globular cluster environment may inhibit planet formation. 47 building planets. If this is the case, then planets may have formed later in the universe's evolution, Tucanae is old and so is deficient in the heavier elements, which were formed later in the universe when stars were richer in heavier elements. Correspondingly, life as we know it may have appeared through the nucleosynthesis of heavier elements in the cores of first-generation stars. Planet later rather than sooner in the universe. 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

25 Bays Mountain Astronomy Club Newsletter March 2018 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. 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. This illustration shows the layers of Earth’s atmosphere. NASA’s GOLD and ICON missions will work together to study the ionosphere, a region of charged particles in Earth’s upper atmosphere. Changes in the ionosphere can interfere with the radio waves used to communicate with satellites and astronauts in the International Space Station (ISS). Credit: NASA’s Goddard Space Flight Center/Duberstein (modiﬁed)

26 Bays Mountain Astronomy Club Newsletter March 2018