Tele Vue Published monthly by PublishedThe Binocular monthly and Telescope since 1985Shop by The55 York Binocular Street, Sydneyand Telescope NSW 2000 Shop 55 York Street, Sydney NSW 2000 the best DECEMBER 2004 * Volume 234 www.bintel.com.au SOLARSOLARSOLAR ACTIONACTIONACTION THETHE SUN’SSUN’S UNUSUALUNUSUAL ACTIVITYACTIVITY THISTHIS YEARYEAR Three times this year there have been days with no observed sunspots on the surface of our star. Sunspots may be seen (with proper filters on a telescope) as dark spots surrounded by shadowy regions on the Sun’s surface. On one day in January and again for two days in mid-October, no sunspots were detected. Physicist David Hathaway of the NASA Marshall Space Flight Centre has noted that the solar minimum is approaching sooner than expected. The Sun’s activity is usually described as an eleven year cycle, although this can vary in length. The time of maximum solar activity and minimum solar activity, The Road Transport Authority has generally called Solar Max amd Solar Min occur about five to six years apart. When maximum activity is occurring the Sun is peppered with sunspots, solar been at it again! With scant regard flares erupt above the surface and the Sun ejects vast clouds of charged gas outwards ito space. Solar observers enjoy this period of increased activity with for surrounding residents feelings, the bonus of the likelihood of seeing flares and auroras. with no thought to the waste of coal- Auroras may well cause power outages in high latitudes, malfunctions in satellites, and interruptions to radio broadcasts. High flying aircraft may be sourced power, they are proposing instructed to fly at lower altitudes when flares occur. The Sun is monitored around the world twenty four hours a day. to erect a giant light tower in the west The solar cycles are not precisely 11 years long as mentioned above. They vary from nine years to about fourteen years. There is no certain way of figuring of Sydney. To make objectors ahead of time whether we will have a short or long cycle. Physicists David Hathaway and Bob Wilson at the NASA Marshall Space Flight Center believe ashamed to complain they are once they have found a way to predict the date of the next solar minimum. Data from the last eight solar cycles have been examined and it was found that the Solar again covering the light polluting Minimum follows two years and ten months after the first day recorded without sunspots. If these figures are correct the next Solar Minimum will be in 2006. monster (and themselves) in a That is about a year earlier than expected. patriotic cloak. Well, I for one think observing the Sun they are a bunch of twerps. Anybody SOLAR SCOPE who thinks that the best way to AA FILAMENTFILAMENT ERUPTSERUPTS with Harry Roberts remember the legendary Light Horse COMPANY TO soldiers is to put up an illuminated, Les Sara Les Sara red-painted, phallic symbol at a Harry Roberts is a keen Sydney highway crossroads needs a reality amateur astronomer with a great JOIN UP WITH check! Or is it simply a way of interest in solar observation. MEADE INC. thumbing their noses at society because they can. See more page 2. Meade Instruments and Coronado Technology Group have ★ ★ ★ Things should start livening up in the signed a deal that sees Meade buying astronomical publishing area. Sky & the solar telescope and filter Telescope’s Australian edition manufacturer. should be on the newsagents’ shelves Coronado is a leading by now. Sky & Space’s current manufacturer of H-Alpha solar filters excellent issue will have to follow which are used to observe the Sun’s up with a blinder in January if they surface and atmosphere. These are to stay the course. Choices... highly specialised and difficult-to- choices! manufacture filters are made under ★ ★ ★ Hydrogen Alpha users often There are in fact two spe- With all the dash of a carefully controlled conditions at I received an anonymous letter witness the weird and the wonderful. cies of filament: the very long Quiet drunken snail the prominence pro- Coronado’s small factory in Tucson, nd regarding what I said about Such was the case on the 22 of Oc- Region Filaments (QRF), and the ceeded to “lift off.” By 02:54 (23 Arizona. creationism in last month’s issue of tober. Morning observations showed shorter Active Region Filaments october, about 4 hours later) I noted Coronado manufactures NIGHT SKY. The letter was well- that a big prominence had appeared (ARF) only found closely involved it “unstable and rising”. By 05:00 it about seven hundred solar scopes and reasoned and sensible... but lacked at the Sun’s eastern limb (Fig 1). with sunspot groups (Active regions, had more than doubled its initial filters each month and is hard-pressed a writer’s name. Pity, it ended up in A prominence is created when AR’s). QRF’s are usually long lived height, and a long thin tendril to keep up with expanding world- the circular filing cabinet. matter (ionised hydrogen) collects at solar phenomena, but as H-alpha re- stretched north to the site of sunspot wide demand. It is understood that the boundary between unlike searcher Prof. Harold Zirin put it in group AR 690. The eruption now Coronado sees advantages in being ★ ★ ★ Do we hear rumours that the great polarities on the Sun’s chromosphere the 1980’s : “Virtually every promi- sped up, and by 06:15 it had ex- allied to Meade as that company has John Dobson is to visit these shores (Fig. 2). Where the unlike fields nence that rises above 50,000 km will panded hugely in both width and very highly sophisticated production 1 again? We do, we do! (hear rumours, “rub” together the right conditions erupt in 48 hours.” height, attaining a height of ~400,000 facilities in California and staff who that is.) If he comes and you can get exit for material to slowly collect in The narrow space formed km, though now quite faint (Fig 3). are able to streamline production for the chance to meet him, do so. It’s a long, stable, serpentine “sausage” between the unlike polarities is analo- At 400,000 km some of the greater efficiency. It may well be that not too often that you get the chance called a filament. A typical large fila- gous to the Lagragian points in huge loop of material was clearly Meade develops a series of filter to meet a real legend. We’ll keep you ment might be 50,000 km high, Earth’s orbit, in that material can col- being drawn back to the Sun by grav- systems designed precisely for their posted. 10,000 km wide, and stretch across lect there without unbalanced forces ity. Calculation gave the rate of ejec- own range of Schmidt Cassegrain ★ ★ ★ the Sun for 500,000km; they are im- tearing it apart. The stronger and tion as a very leisurely 20 km per and Maksutov Cassegrain telescopes. Amateur astronomers in Sydney are pressive “beasts”. Seen from above, more stable the fields, the greater, and second, well under the 618 km/sec There is currently no 3 gearing up for their annual filaments appear as long black shapes higher, the filament grows. Zirin as- solar escape velocity and I assume intention to remove production from Christmas dinners just like stretching across the Sun’s disc in a sures us that the Sun “has trouble all the ejecta, now too faint to see in Arizona and relocate it to Meade’s 2 everybody else. One club is asking wavy pattern. When a filament is holding them down.” . H-alpha, fell back onto the Sun. huge facilities in California. The their members to come along dressed seen side-on, at the Sun’s limb, the When the tall prominence Overall it was a fine example of a twenty five staff at Coronado will as their “favourite astronomical filament is then (confusingly) called (Fig 1) appeared, the first task was QRF ejection, and all part of the continue production of filters and object”. Did they think this one a prominence. When at the limb a to measure its height: I calculated it weird and wonderful world of hydro- telescopes at the present factory at the through? How do you dress as a filament’s height can be accurately over 80,000 km at 22:30 UT on the gen alpha. current time. measured. The word “prominence” 22nd. It was therefore well over 1 Zirin, H. “Astrophysics of the Sun”. nebula? What about a Black Hole? can be applied to any material seen Zirin’s Limit, and the detached north- Cambridge Uni Press. P267. Does a comet slowly melt? How do projected against the blackness of ern end meant that perhaps the ejec- 2 Ibid. you dress to represent certain space at the limb, and includes other tion was already underway albeit 3 Phillips, K. “Guide to the Sun” planets? Hmmm... solar ejecta, in addition to filaments. fairly slowly. Cambridge Uni Press. P188. ★ ★ ★ I’d like to take this opportunity and The Editor of The NIGHT SKY run away with it to a tropical island. together with the staff of The Binocular and Telescope Shop No, not really! But I will take this opportunity to offer all long- would like to wish all our readers and customers suffering readers of Night Sky a a Very Happy Christmas and a Peaceful New Year! Preparing filters at Coronado’s factory. Merry Christmas and A Peaceful New Year! Mel meets French statue .............2 Receive your copy Questions and some answers....