FirstLight Newsletter of the Alachua Club

29° 39'N, 82° 21'W April 1995

Upcoming Monthly Events

Next Meeting — Tuesday, April 11 of . Topic: "Surfing the : Grabbing Astronomical Resources Via • 7:00 p.m. Executive Council Meets. The Internet." Synopsis: An overview of • 7:30 p.m. Business Meeting. astronomy resources available on the • 8:00 p.m. Speaker: Professor John P. Internet, and how one astronomy Oliver, Dept. of Astronomy, University professor uses them in teaching and research.

North Central Florida's Amateur Astronomy Club. Meets second Tuesday May Meeting — Tuesday, May 9 of each month, 7:30 p.m., Doyle Conner 00 p.m. Executive Council Meets. Building, S.W. 34th Street at S.W. 20th 30 p.m. Business Meeting. Avenue, Gainesville, Alachua County, Florida. General public and beginning - 00 p.m. Speaker: Professor Robert E. gazers invited to all meetings, star parties Wilson, Dept. of Astronomy, Univer- and club events. No equipment needed. sity of Florida. Topic: "Can Obser- Call a club officer for more information. vations Live Forever? — The Aston- ishing Case of Beta Lyrae." Synopsis: President Robert Jacobs Alachua (462-4558) Dr. Wilson's talk will discuss one of Vice-President Mark Cowan the best known eclipsing binaries, Beta Gainesville (375-2564) Lyrae, and the role amateurs have Treasurer Doug Richards played observing this star. Gainesville (332-4317) Publicity Pamela Mydock Lochloosa (481-5238) Upcoming Star Parties Star Parties Bruno Pancorbo Gainesville (373-0279) • March 31 (meet at 6:00 p.m. EST). FirstLight Chuck Broward Observing location southeast corner of Editors Melrose (475-1014) Santa Fe Community College on N.W. Howard Cohen 83rd Street (just north of N.W. 23rd Gainesville (376-5833) Boulevard). This location has a clear west horizon free from high trees. World Wide Web Home Page at URL http://nervm.nerdc.ufl.edu/~cohenba Goal is to see new Moon only 21.6 F/rstL/ght: Newsletter of the Alachua Astronomy Club Page 2

hours old. Must be at site about 45 Jacobs' house (see map inside). Moon minutes before sunset (6:47 p.m. EST) one day past last quarter (rises 2:21 if you want to try your luck at seeing a.m. EDT; sunrise at 6:55 a.m. EDT). this incredibly young Moon! Bring Party Events: Lyrid meteor shower binoculars or a small spotting scope if near peak (zenith hourly rate = 15); you have one. search for open clusters. After moonset (7:31 p.m. EST), During second half of night observe proceed to Bob Jacobs' house for continuation of observing. (rises 11:06 p.m. EDT, mag. -2.5); hunt for Uranus (rises 2:23 a.m. EDT, mag. +5.7), Neptune (rises 2:02 a.m. EDT, mag. +7.9), and Pluto (rises April 22 (meet at sunset, 8:00 p.m. 9:38 p.m. EDT, mag.+13.7). 0 EDT). Observing location at Bob

Minutes: March 14 Meeting — Mark Cowan

Attendance: fifteen m e m b e r s , one guest. these and make suggestions. We opened the board meeting at John Brandorff invited ideas for raising 7:00 pm. Doug Richards reported that we money for the club's long range goals. A have $312.03 in our treasury. silent auction, instead of a program at one We discussed future star parties: of our meetings, was a suggestion. Saturday, April 22, at Robert Jacobs, Don Loftus presented his idea for the club coincident with the Lyrid meteor shower. to hold a merit-badge day, for Boy In May we will search for Pluto. Scouts. Jeff Majewski would like to see We reached no consensus regarding our (lie club observe Astronomy Day, May 6. attendance at the Spring Arts Festival as The program was about digital image a club function. processing, by Howard Cohen. He used a The club's constitution and by-laws, from slide presentation which he had designed September 1988, need updating. Mark for pre-college teachers. O- Cowan and Joe Haldeman will review

Authors Wanted!

FirstLight needs writers. Get published! Send material to Howard L. Cohen, Nothing fancy needed. Otherwise, your Editor, 1501 N.W. 28 St., Gainesville, FL newsletter will contain lots of white 32605-5037. Use at least 12 point type; space. Deadline for submission is two print dark. Better, e-mail your material to weeks following each monthly meeting. him at cohenba(fl)nervm.nerdc.ufl.edu. o FirstLight: Newsletter of the Alachua Astronomy Club Page 3

Pluto's Remarkable Crossings — Howard L. Cohen

Pluto travels in an orbit large beyond about 30 to 50 AU. This is enough to human comprehension. Even at the speed allow Pluto to move more than ten of light, a space craft would need five million miles closer to the Sun than hours to reach the realm where this cold, Neptune! mysterious planet roams. From Pluto's Of course, Pluto must "cross" the orbit of orbit, the Earth would shine feebly with Neptune to bring itself this close. the light of a star barely visible to the Collisions might seem possible at these naked eye. However, human eyes could times. However, the inclination of Pluto's not see Earth for their world would orbit to Neptune's (about 15°) makes the always remain within a degree of their minimum distance between the two orbits Sun, shrunken to a point but still blazing 240,000,000 miles, a distance more than with the light of two hundred fifty full two and one-half times the Earth's moons. distance from the Sun. In fact, dynamical Back on Earth, we have watched Pluto effects due to gravitational interactions move only one third of its 248 year orbit between these two planets keep them about the Sun since its discovery earlier positioned in their orbits so Pluto and this century (1930). One Pluto year (248 Neptune never approach each other earth years) consumes more than three closer than 18 AU! average human life spans, a time longer During most of its orbit, Pluto remains than our countiy is old. However, once fainter than apparent magnitude +14, too each orbit, Pluto does something very faint for most amateur size telescopes. remarkable. Although planetary tables list Llowever, as Pluto approaches Neptune's Pluto as the outermost known planet, orbit, Pluto begins to brighten sufficiently Pluto spends more than twenty years to make possible visual sightings in small inside the orbit of its nearest planetary telescopes (with about 200 mm or 8-in. neighbor, the blue-green giant, Neptune. apertures) if skies are very dark and clear. Whereas Neptune has one of the most (See Figure 1 for a graph showing Pluto's circular planetary orbits, Pluto is famous apparent visual magnitude from 1800 to for the most eccentric orbit of any planet. 2300 A.D., a time equal to about two Although a scale drawing of Pluto's orbit Pluto orbits.) appears almost circular, the Sun's position within Pluto's orbit is 25 percent Since Pluto remains brighter than away from the center of the orbit. This magnitude +14 for only about 15 per cent causes Pluto's distance from the Sun to (35 years) of its orbit period (248 years), vary from its average value of 40 AU most amateur star gazers will never (astronomical units1) by 10 AU. Thus, glimpse this faraway planet in their home Pluto's distance from the Sun varies from scopes. Who, in history, has seen Pluto in a small telescope? Relatively few, since the first time Pluto moved within the orbit of Neptune since its discovery sixty-five 'An astronomical unit is the average years ago occurred in 1979! Pluto will distance between the Earth and the Sun. FirstLight: Newsletter of the Alachua Astronomy Club Page 4

remain closer to the Sun than Neptune now! During the next several months, until March 14, 1999 and will dim below Pluto is well placed for observation and the fourteenth magnitude during the first shines near greatest brilliancy at magni- decade of the twenty-first century. When tude +13.7. In April, Pluto rises at about Pluto approaches aphelion (farthest from 10:00 p.m. EDT, and in May near sunset Sun) near the beginning of the 22nd (opposition to the Sun occurs on May centuiy, its apparent magnitude will be 10). Pluto will remain a good evening

Figure 1

Pluto's Apparent Visual Magnitude 1800 A.D.to2300A.D.

+13.5

0) "D +14.0

o> +14.5

c +15.0 0) a. +15.5

+16.0 o o o o o o o o O O O o u> o io o u> o u> o UO O 00 CO or> cr> o o T- CM CM CO r - T- CM CM CM C•^M CM CM CM Year

almost +16, about ten times fainter than object through the summer, but evening Pluto is now. Florida thunderstorms and high humidity will make finding Pluto more difficult Therefore, if you want to "see" this planet because one needs very dark, clear skies. in a typical amateur size telescope, do it FirstLight: Newsletter of the Alachua Astronomy Club Page 5

The current issue of Sky and Telescope discemable 2.2 arc second diameter disk. (April 1995) has a good article about And don't forget to look for Jupiter, viewing Pluto and excellent finding rising in April near midnight. With a charts (see pp. 70-71). In fact, the April magnitude of-2.4, Jupiter is the brightest issue also includes finding charts for both nighttime object (until Venus rises just Uranus and Neptune, which rise four to before dawn). five hours after Pluto and are visible in If you can next find Pluto in your the morning sky. Hence, I have not telescope, welcome yourself to a select included finding charts for any of these group who have visually seen an object planets with this article. If you have that roams the distant, cold, icy fringes of trouble sighting Pluto, try practicing on our solar system. But don't waste time Uranus, which is now at magnitude +5.7 tiying to see its disk. Even when closest and visible in binoculars. With a small to the Sun, this planet, which is only telescope you can see a small two-thirds the size of our Moon, shows greenish-gray disk 3.6 arc seconds an apparent diameter only 0.1 arc across. Then try finding N e p t u n e , dimmer seconds across! © at magnitude +7.9, but easily seen in a very small telescope with a barely

STS-67 (Endeavor) Howard L. Cohen

The recent flight of Endeavor was not Wide Web. According to NASA,1 "Users only highly successful but was also the of more than 200,000 computers from 59 longest mission (16 days) countries logged on to the Astro-2 'home to date. This mission attracted the page,' tracking the missio"s progress and attention of both amateur and leaving messages for the STS-67 crew professional astronomers because members. More than 2.4 million requests astronomy was the focus of the entire for information were recorded over the flight. STS-67 carried an added attraction last 15 days, to the delight of the home for Florida astronomers, payload page administrators at NASA's Marshall specialist Dr. Ronald Parise, who Space Flight Center in Huntsville, received his Ph.D. degree in astronomy Alabama." from the University of Florida in 1979. "This has been an outstanding mission," This shuttle flight was also a public said Astro-2 Mission Scientist Dr. relation coup for NASA; Astro-2 was Charles Meegan. "We had planned to the first S p a c e Shuttle mission to have its explore 23 different science programs own home page on the Internet World and we 'nailed' them all." 0-

1 All quotations taken from STS-67's Internet World Wide Web pages (at URL http://vvww.ksc.nasa.gov/shuttle/missions/sts-67'mission-sts-67.html). FirstLight: Newsletter of the Alachua Astronomy Club Page 6

Star Party at Robert Jacobs — Gilbert Bernardo

At last we enjoyed a decent night of star white while the Odyssey being red; under watching at a planned star party. The site red light, the Odyssey appears almost at the Jacobs' place is more than ade- white. quate. There is a nice border of trees to There was no suitable recipient for the block local lighting, but they are not so five inch refractor that Jan donated to the high as to obscure the usable horizon. It Science Fair, so for the time being, the is about as good as we can get this close club will have a new rich field refractor. to Gainesville. John and Gilbert were using it to explore Several club members were present. We open clusters and nebulae in and around enjoyed views of , and although the the region of Orion. They also compared disk is small, the club six inch showed it to a 4.25 inch Astroscan. The refractor the polar cap nicely and some wispy dark was by far the superior of the two. features. Bruno brought his newly Many thanks to Bob Jacobs for the use of acquired Meade 12.5 inch. Dob and Dale his site. He kindly extended future invi- brought out his big Odyssey. It was tations. I am sure they will be generously interesting comparing the two instru- accepted. o ments. Bruno commented on the differ- ences in paint jobs, his being a stark

Viewpoint — Robert Jacobs At our latest star party several of our thoughts to beginning star gazers. My observers saw what they called double experience, in this respect, has been stars through their eyepieces. Does this mostly on the receiving end of the talk. mean that what they described was two Our reference terms should indicate, stars from a single system that were in where necessary, that apparent size and somewhat close proximity? Not exactly. position is our meaning so that the in- Did this mean that the stars were part of experienced audience will not be "tuned a single galaxy? Not exactly. Were they out." In this way, we can be sure of hold- even assumed to be the same distance ing our listeners and then aid them in from our own solar system? Not exactly. building their vocabulary in astronomical What, then, were the observers terms. Let's face it, even "sky" has describing? meaning — but only on the earth's surface. When we look at deep sky objects and make reference to them, we include our Proper description relates die idea to the experience. Communicating to others term used and aids understanding. Put what we see, like brightness, position and that in action when your time comes to color, we use that experience and we speak to others of the stars and planets. « must allow for this when relating some FirstLight: Newsletter of the Alachua Astronomy Club Page 7

Directions to Bob Jacobs — Howard L. Cohen

Address is 9617 N.W. 143rd Street Note: Bob's driveway is paved and (HWY 241). See map below. marked by a five foot high, brick mail- box. (A sign past the mailbox reads From 175, go 2.9 miles west on 39th Hurricane Harbor.) It is a few hundred Avenue (HWY 222) to N.W. 143rd feet up the driveway to Bob's house. (Do Street (HWY 241). Note: N.W. 39th not continue up the paved driveway onto Street ends at N.W. 143rd Street. Turn a dirt road — you will pass his house.) north (right) on 143rd Street. If you come from Alachua, go south on Go 3.5 miles north on N.W. 143rd Street HWY 241 (143 Street). Bob's dnveway to N.W. 94 Avenue. Curves precede the is 0.7 miles past the 175 overpass on the approach to N.W. 94th Avenue. An left-hand (east) side of 143rd Street. intersection sign marks the approach to the junction of N.W. 94th Street and Note: Driving time from Santa Fe N.W. 143 Street. Community College Campus (on N.W. 83rd Street) to Bob's place is about ten Note: N.W. 94th Street is also 1.6 miles minutes. If you arrive after dark, please north of Millhopper Road (HWY 232). use only parking lights as you come up Go 0.1 miles past 94th Avenue. Bob's Bob's driveway. There are restroom driveway is on right-hand (east) side of facilities but bring lawn chairs and snacks 143rd Street. (and some to share). O

175 Overpass

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232

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s: ^ \ 993 B( Lorrai^hvtjniruI ' April Astro Calendar (Times EDT) Sun 2 2h Eastern Daylight Time Begins i .S chu

Sat 8 2h First Quarter Moon r < . Br

73 s Thu 13 13h Venus 0.6° Degrees North of Saturn a A Fri 14 9h Mercury at Superior Conjunction 3 o Sat 15 5h Spica 1° South of Moon ca rjrj S 55. m

Full Moon nom 8h -n o d aj s ^ i X , Edito Fri 21 23h Last Quarter Moon r~ N3 3

Sat 22 11h Lyrid Meteor Shower Peaks (ZHR=15) to y Clu Wed 26 Martian Summer Soltice: N. Hemisphere h r

en t Thu 27 1h Venus 4" South of Moon b 17h Neptune Stationary Sat 29 14h New Moon