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Qj < ro •-3 1 M co CO M (D n ro as ro o I fD fD 3 - crrt r- c *< 01 o en - Cr t ai X OJ ro i— 3 c 3 o M QI n Ml r0o1 r COo 3 n M. 3 c W R) 3 N rr r r 3 s»r QJ rc fD CD 3 -D I—• v£> < M M rr M «e Qi "3 r t M QJ S3 M 5 QJ g CO l— I-J rr Mi n M 3 > r 3 r t M C O fD QJ 3 o Pi cn n 3- «: rr fO t-> a* (D ro * 3 ro fD o t r OJ O QJ >0 01 M O i-" 3- ro fD cr tr oo H" fD a ca M < < M ^ fD CO fO a oa f t 3* r t ro i-" I in. ' • .. n '•'. '! Mil I 1 ..:•.: . >< by Charlie Tazjan DID YOU KNOW ?????? One of the amateur's richest experiences is getting out during a reasonably dark night, looking up at the constellations, and knowing what's up there! One remembered disappointment in my life was my complete ignorance of the Australian skies once when I was in the "outback". The night was dark, we were in the middle of nowhere, and the sky seemed to be filled with a billion stars, seemingly fighting each other for space to exist. If ever I felt awed by the infinite, it was at that moment — but at least it did get me "turned on" to astronomy! One of the best things I did afterwards was to subscribe to the Abrams Planetarium monthly skymaps (Sky Calendar, Abrams Planetarium, Michigan State University, East Lansing, MI 4882 4. Subscription: $6 per year) which are excellent constellation guides. So, what's up there in June worth looking at?? Plenty!! it was only the end of May when George Russell and I went out one night and trained the telescope on Venus shining almost as bright as usual. Wow, were we shocked to discover that "bright" Venus was only a crescent, much like a new moon! The big and little dippers are quite prominent in June, although the stars between Polaris and the far end of its cup may be hard to pick out without lenses. Shortly after twilight when the stars start to stand out clearly, let's say about 9:15pm or so, you should visually follow the handle of the big dipper, about 2-1/2 times the handle length to a very bright star, Arcturus, which is in the constellatiom Bootes. Bootes looks something like a parachute with its blunt end pointing east of the two dippers, be sure and look east of "the canopy" of Bootes for the Corona Borealis appearing as a large letter "u". If you continue to look south, about 1-1/2 times the length of Bootes you will see another bright star, Spica, which is in the constellation of Virgo. Virgo appears as a "Y" with its "leg" pointing south southeast. Don't overlook the very easy-to-spot constellation Corvus which appears as a small trapezoid t o the southwest of Spica. Using Arcturus as our basepoint, another fairly bright star appears about twice the length of the big dipper to the west of Arcturus. This is Regulus, the brightest star in the constellation of Leo, which is somewhat hard to describe but does exhibit "the Sickle" (another "u-shaped" object) to its north. The open end of the Sickle is to the west. The two bright stars you see to the northwest are the Gemini twins, Pollux and Castor. The other night they seemed to be almost stationary for the 90 minutes or so that we were observing the skies. Cassiopeia is supposed to be near the northern horizon but I've yet to see it because of skyline vegetation, in like manner, Antares, in the constellation Scorpius is on the skyline to the south southwest. While you're looking in a southwest direction and if you stay out long enough you'll be rewarded with a view of Saturn which should appear earlier and earlier as the month wears down. The last heavenly body to look for is a "whopper" and will be found to the east northeast. This one is the "summer triangle" which includes stars from three constellations: Deneb in the constellation Cygnus, Vega in the constellation Lyra, and Altair in the constellation Aquila. Deneb is also the northernmost star in the Northern Cross which is also within Cygnus. Incidentally, don't forget the mosquito repellent and try wearing a bandana draped from your cap around your neck. It might help!!! _w •'•«:•( UOY ; LQ • • , >"->;Jc..i..i:). . • ! 1 !.Ibi •• m .... • "'o b '• • • ! h : • i . •.••, i I • iff: 1 1 : '• i. " '" t 1 "'•'•. ; . 1 • ih: • • , • ! i ' c„ •• | 1 ; . • , • . r. .1 • B •',-.. ."l l" 1-j. ] t i> ' - ;•->< VMI . I". :'• '.' 1. ' 1 .' 1 ": ' : ' ••• : ' •' • ' . Ml :>i : • • '.'.>•''•'': • 1 i ' ,. • " , , • i IV.'Iff • 1 !:!-!< . •! ' ' ' • • - ' :. ' ; - • • * ! 1 i - ' " • • .' : • •.. 'I'.rJiH .•'...• Oi 'id •'"> J '.:•"'-•. • iii t ' : i" ' i <. • • •• ". • i • . :. • ': I • V • •' J J. -. W < i j -f ;if I : ij 1 ,'•• :.-'.. < • \: • ,!T >• . i r Tl ; . • ' ' I ,••' . . '• .. • :•: JUNE 198B All tines Eastern Daylight Prepared for Delaware Astronosical Society Copyright 1988 Robert F. Wieland J, + Sunday Monday Tuesday Wednesday Thursday Friday Saturday 29 HAY 88 ! 30 HAY 88 ! 31 HAY 88 ! 01 JUN 88 ! 02 JUN 88 ! 03 JUN 88 ! 04 JUN 88 1 ^ FULL HOON 6:53 ! Hoon 24' S o f Hoon 5 d e g S o f Antares, 6:00 Uranus, 17:00; (occultation 6 deg S o f Hoon 6 d e g S o f Tau Herculid Alpha Circinid ! for Australia) Saturn, 18:00 Neptune, 8:00 meteor shower meteor shower 1 ! 05 JUN 88 06 JUN 88 07 JUN 88 08 JUN 88 09 JUN 88 10 JUN 88 11 JUN 88 ! LAST QUARTER HOON 2:21 Hoon 6 d e g N of ! Jupiter 23:00 ! Hoon occults ! Comet Finlay Hininun of Phi Aquarius 2:32 Hercury at ! ! at perihelion Algol 5 : 2 7 ! aphelion ! Arietid & ! Scorpid Hoon 2 d e g N Zeta Perseid Minimum of Sagitariid ! ! meteor shower of Hars 16:00 ! meteor showers Librid meteors Algol 2 : 1 5 1 meteor shower ! + + 12 JUN 88 13 JUN 88 14 JUN 88 15 JUN 88 16 JUN 88 17 JUN 88 18 JUN 88 YEAR'S EARLIEST NEW HOON 5:14 SUNRISE 4 : 3 1 Moon crosses Hercury at Pleiades inferior before dawn conjunction, 0:00 Minor Planet 2 Pallas Venus at inferior Theta Ophiuchid Alpha Scorpiid June Lyrid Hoon near 1.5' SSH of conjunction 20:00 meteor shower meteor shower meteor shower Castor & P o l l u x U Delphini 5:30 + + 19 JUN 88 20 JUN 88 21 JUN 88 22 JUN 88 23 JUN 88 24 JUN 88 25 JUN 88 SUHHER SOLSTICE FIRST QUARTER 23:57 6:23 Uranus & Saturn Moon 1.2 deg N o f at opposition Moon 1.1 deg S Regulus 14:00 0:00 & 5:00 of Spica 4:00 (occultation (occultation for the Arctic) Ophiuchid meteors for Antarctica) 26 JUN 3S 27 JUN 88 28 JUN 88 29 JUN 88 30 JUN 88 01 JUL 88 02 JUL 88 YEAR'S LATEST MOON FULL 15:46; SUNSET 7:33 6 deg S of Saturn linimum of i 5 d e g S o f Algol 7 : 0 8 Uranus 0:00; 6 d e g Hoon occults S of Neptune 16:00 Saturn 1.3 deg N 1 Scorpii 0 : 0 0 of Uranus 22:00 Beta Taurid & Moon 24' S o f June Draconid Neptune at Corvid meteors Antares 15:00 meteor showers opposition 6:00 • Another Look at the Drake Equation or E.T. Phone Home, But Was Anyone There? Part II Last month I presented my reasons as to why I feel that the current SETI experiments imply that there are fewer than one million intelligent, communicable civilizations in the galaxy. I also pointed out a major problem with the current (and planned) SETI experiments, namely that a civilization must transmit in the radio frequencies we consider "likely" channels for interstellar communication in order to be detectable. If the intelligences "out there" do not transmit in this set of frequency ranges, then we won't detect them, and we are wasting time and money. This month I am going to discuss the Drake equation, that infamous equation which supposedly gives the number of intelligent, communicable civilizations in the galaxy, and hopefully convince you that civilizations are a rarity in the galaxy, numbering far fewer than the one million figure quoted by many SETI advocates. Here goes... Let me begin by writing down the Drake equation, after which I will explain what each symbol means... N = SxPxExLxIxC where N is the number of communicable civilizations in the galaxy, S is the number of stars in the galaxy capable of sustaining life. P is the probability that a star will have planets, E is the probability that a planet is capable of sustaining life, i.e., the chances that a planet is habitable, L is the probability that life will evolve on a habitable planet, I is the probability that intelligent, civilized life will evolve from less complicated organisms, and C is the fraction of the star's lifetime that the civilization lasts. Before we begin, a word of caution - When a scientist talks about life, he is referring to life as we know it We are not postulating the existence of lifeforms based on other elements, like silicon. Further, we assume that the same principles that govern the evolution of life here on earth also apply to other worlds. With that in mind, let us now look at each of the terms of the Drake equation and see if we can come up with some numbers. The number of stars capable of sustaining life (S) - We know there are about 400 billion stars in the galaxy. But are all of these capable of sustaining life as we know it? The answer is definitely not, as intelligent(?) life on earth has taken 5 billion years to evolve, requiring the Sun to have been stable for this length of time. Stars much bigger than the Sun have a lifetime of only a few hundred million years, so we can eliminate them as candidates. Stars much smaller than the Sun do not produce much in the way of heat, requiring any possible life-supporting planets to be very close to the star's "surface" and vulnerable to flares. Further, such stars are often variable in the amount of radiative energy they produce, again making it tough to develop life. We can therefore conclude that a star must be similar to the Sun in order for it to be capable of sustaining life. Such stars account for about ten percent of the stars in the galaxy, so S = 40,000,000,000 or 40 billion . ' • •I . ! [n •. • . . , ' ' ' ! ' The fraction of stars with planets (Pj - AS of yet, we have no conclusive evidence for pianets in orbit about other stars. However, there are some tantalizing clues and hints (which hopefully will be resolved by Space Telescope) that most stars have planetary systems. Lacking any better figure, let's assume seventy-five percent of the stars in the galaxy have planets. Thus, P = 0.75 or 3/4 The number of habitable planets around a star (E) - If we use our Solar System as an example, we get a number of 1. However, the latest computer models indicate that life can develop on a planet only if it meets the following conditions 1. The planet must have a mass between 85% and 120% that of Earth. 2. The planet must rotate fairly rapidly, i.e., have a length of day similar to that of Earth. 3. There must be large amounts of liquid water (oceans) on the surface. The scientists behind these models estimate that only about one out of every one hundred solar-type stars will possess such planets. Based on these results, let us assign E = 0.01 or 1/100 The probability that life will develop on an habitable planet (L) - We really have no idea as to the value of this part of the equation. Let us therefore adopt a middle-of-the-road stance and set L equal to 50%, thus assuming that half of all habitable planets develop life. So L = 0.5 or 1/2 The probability that life will evolve into a communicable civilization (I) - To get an idea of this number we turn to the work of evolutionary biologists, who are the experts in this sort of thing. They say that the odds of an intelligent species developing from single-celled organisms are about 1 in 100 million. In fairness, I will state that this is the majority opinion, and that there are notable dissenters, such as Stephen Gould, who argue that this number is much closer to one. But, let us stick with the majority opinion and assume I = 0.00000001 or 1/100,000,000 The fraction of a star's lifetime that a communicable civilization exists about it (C) - This is another one of those "Pick a number" terms. How long can a civilization survive? Will we blow ourselves to bits in the near future? If we do so, and all civilizations follow suit,destroying themselves after a few hundred or thousand years, then C is very small, on the order of one in ten million! But if this is not the case, then there should be no reason why a civilization could not last through most of a star's life, perhaps even moving to another star as theirs dies. Again, let us take a middle-of-the-road stance and say C = 0.5 or 1/2 Now let us put everything together and see what results: N = 40,000,000,000 x 0.75 x 0.01 x 0.5 x 0.00000001 x 0.5 = 0.75 Hmmm...According to these numbers, it would seem there is only one civilization in the galaxy - us! Certainly not a million. Then, why SETI? Because a SETI scientist would argue that I is much closer to one, say one in a hundred, giving N = 750,000, • I •l ( FO I ' ' <••:•. " > ' which is much closer to the often-quoted figure of one million. It all boils down as to which term is dominant - the number of stars capable of supporting life (S), or the chances of a civilization evolving from single-celled organisms (I). If the SETI people are right, then S is the dominant part and we have lots of civilizations. If the majority biology opinion is right, then I dominates and we could very well be alone in the galaxy. Personally, I think I'll listen to the biologists - after all, they're the experts when it comes to life. I don't necessarily think we're the only civilization in the galaxy, but I do believe there are very few of them out there (less than one hundred). As a result, 1 don't think we will ever detect any signals from alien civilizations, and so SETI is wasting much-needed money that could help revitalize a floundering space program. Even if I'm wrong, and there are many civilizations in the galaxy, we will eventually discover them as we move out into the galaxy. That's it If I've got you to think a little about SETI and extra-terrestrial intelligences, then I've accomplished my purpose, whether you agree with me or not "Thinking is a great thing for a person to do - astronomers should do it more often. SST-SPECTROSCOPIC SURVEY TELESCOPE George Russell More than half of all professional astronomical observations involve spectroscopy. Spectroscopy involves the analysis of light that has been sep- arated into its component colors or wavelengths. Astronomers use spectro- scopy to acquire such vital . i n f o r m a t i o n as the compositions, m o t i o n s , temper- atures, pressures, d i s t a n c e s , and ages of celestial objects. Astronomers from Pennsylvania State University and the University of Texas are building an innovative telescope dedicated to spectroscopy. Unlike tradi- tional multi-purpose telescopes, the SST is designed to m i n i m i z e costs while maximizing efficiency of a single function. When dedicated, the SST will con- sist of seventy-three 36 inch diameter mirrors. All of the mirrors will be ar- ranged in a single large framework to form a single mirror with an effective ap- erture of 8 m e t e r s (about 25 feet) in diameter. This is larger than any tele- scope currently in u s e . The SST will rotate in azimuth (parallel to the horizon) but not in alti- tude ( u p and down). It will take advantage of earth's spin on its axis by let- ting the sky move through its chosen field of view for any given set of obser- vations . The collected light will be brought to a focus at a moving assembly on top of the telescope. As the sky "drifts by", this focal plane assembly will auto- matically track the star or galaxy being observed for up to an hour, more than enough time to acquire detailed spectroscopic information from almost any astronomical target. A small TV camera will travel along with the focal plane assemblyto help locate and track desired objects in the sky. Most of the light, however, w i l l be fed from the telescope focus to a separate room through a long set of fiber optics. The spectrographs will be located in this other room. Because of the use of small inexpensive mirrors, along with a number of other design innovations, the SST will cost about $6 million, as opposed to the $50-100 million cost of a telescope with a comparable single-surface mirror. The SST will be located at the University of Texas at A u s t i n McDonald Observatory in Ft. D a v i s , T e x a s , and should be operational by 1 9 9 1 . The foregoing was adapted from the May/June 1988 issue of STAR DATE p u b - lished by the McDonald Observatory Public Information office by the University of Texas at A u s t i n .
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