Download disini=>LIST NAME OF REMEDIAL TEST
Polaroid
Polaroid SX-70
From Wikipedia, the free encyclopedia
polaroid
http://en.wikipedia.org/wiki/File:Polaroid_SX-70.jpg
http://upload.wikimedia.org/wikipedia/commons/6/69/Polaroid_SX-70.jpg
SX-70 Model 2 with film cartridge protruding from the front
A half-collapsed SX-70
A fully collapsed SX-70
The SX-70 is a folding single lens reflex Land Camera which was produced by the Polaroid Corporation from 1972-1981.
Contents
[hide]
History
Though Polaroid had considered a Henry Dreyfus-designed SLR for its Colorpack film, the SX-70 was the first instant SLR and the first camera to use Polaroid’s new SX-70 integral print film, which developed automatically in broad daylight without the need for intervention from the photographer. The SX-70 was also notable for its elegant folding design, which allowed the camera to be compact enough to fit a man’s suit-jacket pocket when collapsed.
There were a variety of models beginning in 1972 with the original SX-70, though all shared the same basic design. The first model, sold in Florida in late 1972, had a plain focusing screen (the user was expected to be able to see the difference between in- and out-of focus) because Dr. Land wanted to encourage photographers to think they were looking at the subject, rather than through a viewfinder. When many users complained that focusing was difficult, especially in dim light, Dr. Land was forced to include a split-image rangefinder prism of the kind used on 35mm SLR focusing screens. This feature is standard on all later models.
The later Sonar OneStep and SLR 680 models were equipped with a sonar autofocus system, which permitted returning to the plain focusing screen. The Sonar Onestep models were the first autofocus SLRs available to consumers. (Polaroid Corporation marketed this relatively inexpensive, novel sonar technology as a set of components to hobbyists in order for them to incorporate distance sensing into other systems.) The later SLR 680/690 models updated the basic design of the Sonar Onestep to more modern standards by incorporating support for newer 600 cartridges instead of SX-70 cartridges, and a built-in flash instead of the disposable Flashbar. Today they are the most evolved forms of the SX-70, and are highly sought after by Polaroid enthusiasts[citation needed].
Though expensive, the SX-70 was popular in the 1970s and retains a cult following today[1].
[edit] Design features
The SX-70 included many sophisticated design elements. A collapsible SLR required a complex light path, with many mirrors (including one Fresnel reflector) of unusual, aspheric shapes and at odd angles. Many mechanical parts were precision plastic moldings. The body was glass-filled polysulfone, a very rigid plastic which could be plated with genuine copper-nickel-chromium. This plating looks and feels so much like solid metal that some users still insist the camera is solid stainless steel.[dubious – discuss] Models 2 & 3 would switch to the less-expensive and more-easily cracked ABS in either Ebony or Ivory color. The film pack contained a flat, 6-volt “PolaPulse” battery to power the camera electronics, drive motor and flash. The original flash system, a disposable “Flash Bar” of 10 bulbs from General Electric, used logic circuits to detect and fire the next unused flash.
[edit] Models
The original SX-70 was a high-end consumer market camera, with a folding body finished in brushed chrome and genuine leather panels. It could utilize a whole array of accessories, such as a close-up lens (1:1 @ 5 inches), electrical remote shutter release, tripod mount and an Ever-Ready carrying case that hung from the neck and unfolded in concert with the camera. Most of the same technology was later sold in rigid plastic fixed-focus versions, Pronto, Presto and OneStep. In its heyday, the OneStep’s simplicity, bargain price and use of the same instant film made it the #1 selling camera in the USA.[citation needed]
[edit] Film history
Polaroid SX-70 film was introduced to the market in 1972, and was a market success despite some problems with the batteries on early film packs. The original SX-70 film was improved once in the mid-’70s (New Improved Faster Developing!) and replaced in 1980 by the further advanced “SX-70 Time-Zero Supercolor” product, in which the layers in the film pack were altered to allow a much faster development time (hence the “time zero”). It also had richer, brighter colors than the original 1972 product. There were also professional market varieties of the SX-70 film including 778 (Time Zero equivalent) and the similar 708, Time Zero film without a battery, intended for use in applications such as the “Face Place” photo booth and professional or laboratory film-backs, where a battery is not needed. Time Zero was the film manufactured up until 2005, though overseas-market and some last run film packs were marked only as SX-70.
A feature of the SX-70 film packs was a built-in battery to power the camera motors and exposure control, ensuring that the battery would never be exhausted as long as film was in the camera. The “Polapulse” battery was configured as a 6 volt thin flat battery, and used zinc-chloride chemistry to provide for the high pulse demand of the camera motors. [1] Polaroid later released development kits to allow the Polapulse battery to be used in non-photographic applications. [2]
[edit] Film issues
This article’s Criticism or Controversy section(s) may mean the article does not present a neutral point of view of the subject. It may be better to integrate the material in those sections into the article as a whole. (February 2010)
This section may contain original research. Please improve it by verifying the claims made and adding references. Statements consisting only of original research may be removed. More details may be available on the talk page. (February 2010)
Polaroid’s SX-70 “Time-Zero” film was phased out of production in late 2005 to early 2006 (differing according to regional markets). Small quantities of the film may still be acquired, however at often very highly inflated prices. Thus, SX-70 users are left with two options for using new film in their cameras:
Polaroid SX-70 Blend Film
In October 2006, a brand new SX-70 film pack was licensed by Polaroid and produced at the Netherlands plant in small batches, with only word of mouth and Web to advertise it. It very cleverly used an integrated neutral-density filter and modified 600 film chemistry to yield vibrant colors, strong contrast, and high resolution. As the cartridge was made to its original SX-70 specifications, and the ND filter was placed over the opening of the film pack and not the lens, it allowed for full and normal use of all the camera’s functions. Unfortunately, when Polaroid ceased production of all film, the SX-70 Blend died as well.
Polaroid 600 film
Many SX-70 owners modify their cameras to use Polaroid’s more recent 600 film, although it is now discontinued. SX-70 and 600 film are not exactly the same, however, the 600 having some extra little ‘nubs’, so photographers must either use a playing card or dark slide from a used Polaroid film pack to help slide the 600 film into the camera or slice the nubs off the cartridge.
Another problem with using 600 film is that its speed is two stops faster than SX-70 film, causing overexposure. To address this issue, some photographers simply set the exposure dial all the way to “darken” and replace the small ND filter over the electronic eye with a similar clear filter. Polaroid itself recommends placing a 1-stop ND filter over the lens, and replacing the small ND filter over the electronic eye with a clear piece of plastic (as from a CD case). Even with these modifications, SX-70 users may find they need to set the exposure controls fully to “darken.”
Perhaps the most effective way to use 600 film is to have the SX-70′s exposure electronics electronically modified to accept the film’s higher speed. The advantage to this type of camera modification is that the camera will expose the film correctly without the use of filters or exposure adjustments. Full exposure control is retained, and one does not have to worry about forgetting to set the exposure to “darken” each time the camera is opened. Furthermore, this type of modification allows the camera to benefit from faster exposures, as it causes the camera to function at a true ISO 640 film speed. These modifications are very difficult to perform except by experienced camera technicians.
Impossible Project
While Fujifilm still produces some of the older-style, professional ‘peel-apart’ films, Polaroid’s Enschede, Holland film plant was the last manufacturing center for the ‘integral’ SX-70, 600 and Spectra films. However, in late 2008 several former employees of the Polaroid plant and Florian Kaps (the Austrian entrepreneur behind the effort) undertook the aptly named Impossible Project ( http://www.the-impossible-project.com )
They were able to take a lease on the plant and intercept the 9 integral-film assembly-machines before they were cut up and hauled off for scrap. They are currently working from scratch to create new development chemicals so that they can begin selling new versions of the 125 and 600 ASA films in 2010.
On 22 March, 2010, Yahoo News reported that the “Impossible Project” had borne results in the form of “instant film,” which was reported by the Associated Press’ Technology Writer Peter Svensson.
The Associated Press’ article said: “A group of engineers and enthusiasts who leased an old Polaroid film factory in the Netherlands announced Monday that they had successfully reinvented instant film and will start selling packs this week.”
[edit] Image manipulation
A “manipulated” photograph of a Chevy Nova
One feature of SX-70 integral print film is its ability to be manipulated while developing, and for some days after. Because the emulsion is gelatin-based, and the Mylar covering does not allow water vapor to readily pass, the emulsion stays soft for several days, allowing artists to press and manipulate the emulsion to produce effects somewhat like impressionist paintings. An example of this technique was used on the cover of Peter Gabriel’s third album, Peter Gabriel.
The 500, 600, and Spectra/Image materials do not use a gelatin-based emulsion, and cannot be manipulated this way.
Manipulation of the photograph is best done about two minutes after the picture has fully developed. It will stay soft and workable for about 5–15 minutes. Some colors will be more difficult to work on (dark green), whereas others are workable for a long time (red). If the photo is on a warm surface or slightly warmed in an oven, image manipulation is made easier.
Pergeseran dan Pembalikan Kutub di Tahun 2012
Sabtu, 24 Januari 2009
Oleh: Patrick Geryl
2012 era: Pada 2012 pembalikan kutub akan terjadi di bumi. Ini artinya kutub utara akan berubah pindah ke kutub selatan. Secara ilmiah ini hanya bisa dijelaskan dengan fakta bahwa bumi akan berputar atau berotasi dengan arah sebaliknya, bersamaan dengan terjadinya bencana yang besarnya belum diketahui.
Di banyak buku-buku saya, saya mengungkap bencana alam yang sangat besar yang akan mendera bumi dalam beberapa waktu ke depan yang tidak terlalu lama lagi. Diasumsikan oleh sebagian besar orang dan ilmuwan secara umum bahwa bumi berotasi secara stabil, bagaimanapun juga, seperti di jelaskan pada apa yang saya kerjakan mengenai masalah ini, bahwa bukan itu masalah sebenarnya. Laporan-laporan mengerikan mengenai malapetaka yang terjadi sebelumnya seharusnya telah menjadikan semuanya lebih jelas.
Eksplorasi historis mengenai kosmologi (cabang ilmu metafisika yang berhubungan dengan alam dan semesta) di buku-buku sebelumnya ditemukan pada terjemahan tulisan hieroglif, pemecahan kode-kode, penemuan pembalikan daya magnetis matahari, pembelajaran peta-peta kuno, pengkodean ulang petunjuk-petunjuk astronomis, riset geologis, dan penemuan arkeologis di jaman moderen:
1. seperti kebiasaan jam berjalan secara normal, pembalikan kutub bumi secara tiba-tiba adalah sesuatu yang normal. Hasilnya adalah kehancuran dunia, dan didukung dengan bukti2 paleo magnetis dan manuskrip2 kuno
2. pembalikan kutub adalah salah satu proses dalam siklus harmonisasi medan magnet pada matahari
3. pembalikan kutub dapat dihitung dengan tepat dengan berdasar pada teori siklus bintik matahari atau teori medan magnet, yang banyak dikuasai oleh bangsa Maya dan mesir kuno. Rahasia2 ini disimpan di Labyrinth of Hawara, sebuah tempat sangat besar yang memiliki 3000 ruangan.
Saya menjelaskan secara panjang lebar dan jelas sebab kehidupan setelah pembalikan kutub adalah kehidupan horor dan benar2 murni horor. Semua keamanan yang kita miliki, makanan, transportasi dan obat2an akan hilang dalam satu kali ledakan saja, semuanya hilang ke dalam ketidakadaan. Tidak akan lebih mengerikan dari hal ini, ini lebih buruk dari mimpi buruk. Lebih destruktif daripada perang nuklir yang gudang senjatanya diledakkan dalam satu kali ledakan saja. Apakah anda menangkap faktanya?
Bumi akan dihancurkan secara total. Dan akan lebih parah daripada penjelasan saya. Kelaparan yang mengerikan, dingin dan sakit, dan lebih dari itu semua akan menjadi keseharian anda, tanpa harapan penyembuhan dan perbaikan secara cepat, karena semua pengetahuan dan sumber2nya akan dihancurkan secara total. Ini akan menjadi realitas pada keseharian kita setelah pembalikan kutub. Dan dalam skenario ini anda akan berusaha untuk bertahan.
Teka-Teki Medan Magnet Terpecahkan
Sekarang para ilmuwan masih belum mengetahui banyak tentang mekanisme yang membangkitkan medan magnet bumi. Tidak ragu lagi bahwa kelanjutan eksistensi kita bergantung pada ini. Ribuan tahun lalu, para pendahulu kita mengetahui bahwa jika medan magnet ini miring, maka akan terjadi kehancuran seluruh dunia. Ahli geologi, astronot dan ahli fisika hanya tahu sedikit mengenai hal ini. Maka dari itu kita sebenarnya sedang menuju hari kiamat, tanpa mengetahui tentangnya dari sumber-sumber yang jelas.
Jadi apa yang perlu diketahui oleh para profesor kita? Tidak ada! Secara singkat, skenarionya seperti ini : sebuah inti berotasi di tengah bumi. Dikelilingi oleh lapisan besi cair, di atasnya kerak bumi terus mengalir. Seluruh struktur ini tampak seperti dinamo yang sedang berputar. Dan, lapisan besi cair berotasi pada medan elektrostatik matahari serta melakukan pengisian tenaga secara otomatis.
Bagaimanapun juga hal ini tidak efisien : pengeluaran tenaga elektrik lebih banyak daripada pemasukannya. Seperti batere yang hampir kosong sehingga susah untuk di charge dan menjadi semakin mudah dan cepat lelah. Inilah situasi batere medan magnet bumi. Karena alasan inilah orang melihat kekuatan medan magnet menyusut sebanyak 60 % selama lebih dari 2000 tahun terakhir.
Pada level ini tidak ada waktu yang tersisa kecuali hanya beberapa dekade saja! Dan kemudian terjadilah pembalikan kutub. Tapi tidak ada seorang pun yang mengetahui bagaimana proses terjadinya, ataupun konsekuensi yang akan terjadi, sebaliknya dengan bangsa Maya dan mesir kuno yang mengetahui konsekuensi2 mengerikan. Ilmu pengetahuan mereka, agama mereka dan way of life mereka benar2 didasarkan pada hal tersebut. Mereka menerjemahkan pengetahuan mereka dalam angka2 suci dan arsitektur mereka.
Saya membutuhkan berhari-hari, berbulan-bulan dan tahun untuk mengikuti petunjuk2 mereka secara hati2 dan menerjemahkan kode2 itu. Setelah pencarian panjang, saya menemukan bahwa kode2 ini terhubungkan dengan peristiwa2 besar di bumi yang disebabkan pergeseran kutub. Beberapa kodenya sangat rumit walaupun tetap dapat dimengerti. Begitu anda menemukan kuncinya, anda akan dapat mengetahui tingkatan2 yang berbeda pada bahasa ilmiah mereka. Kemudian anda dapat mengupas lapisan demi lapisan secara literal sampai anda meraih hasil mengenai latar belakang bencana2 itu.
Teori Bintik Matahari yang tak dikenal Menjawab
Jawaban2 atas pertanyaan2 ini sangat menakutkan. Seluruh uraian saya menunjuk kepada sebuah ilmu pengetahuan yang kompleks dan luar biasa. Ketika anda, sebagai seorang ilmuwan, menemukan sesuatu yang tidak diketahui oleh para ahli astronomi, maka tidak ragu lagi telah menemukan sesuatu yang sangat penting. Semua orang harus mengakuinya, dan inilah yang sebenarnya telah saya lakukan : Saya menemukan gema dari terminologi teknologi yang telah lama hilang, sebuah bangunan agung dengan kunci yang canggih. Angka2nya didasarkan siklus bintik matahari, yang telah mereka temukan. Sebuah teori yang tak dapat dibantah kebenarannya dan belum diketahui oleh para ahli fisika kita. Tidak ada yang lebih menakutkan daripada ini …
Teori ini, pada gilirannya, berhubungan dengan periode pembalikan kutub bumi. Saya sukses menyelesaikan seluruh teka-teki dan sebuah struktur besar yang muncul. Pengembangannya sangat matematis dan berakhir pada hari terjadinya pembalikan kutub.
Seperti saat kita menghitung mundur peluncuran roket, mereka menghitung mundur ke akhir waktu. Pada hari terakhir dari kalender kutub utara akan berubah menjadi kutub selatan. Mereka tahu ini bukan saja akhir dari peradaban mereka, namun juga akhir peradaban dunia!
Kilatan Matahari Penyebab Pembalikan Kutub
Dari beberapa legenda dan teori siklus bintik matahari suku maya, kita dapat mengkonstruksi ulang penyebab pembalikan kutub. Hal ini telah lama diketahui ketika sinar menyorot magnet, maka kutub magnet itu akan bertukar tempat. Mari kita menerapkan konsep ini dalam skala yang lebih besar.
Bumi kita adalah magnet besar, dengan kutub selatan dan utara. Sirkuit pendek dengan sorot sinar , atau magnet, dapat berakhir pada bencana pembalikan kutub. Ini artinya kutub utara akan bertukar tempat dengan kutub selatan. Tapi apa yang dapat menyebabkan ini? Kekuatan apa yang cukup kuat untuk menghentikan rotasi bumi dan membalikkan rotasinya?
Hanya satu yang dapat melakukan ini: yaitu Matahari. Anda tahu di dalam buku saya, The Orion Prophecy, dikatakan bahwa medan magnet matahari mengalami perubahan drastis setiap 11500-12000 tahun. Begitu mencapai titik puncak, daya magnet tersebut akan berbalik secara instan. Kesemrawutan akan membarengi fenomena ini dan sebuah awan plasma yang sangat besar dan luas terlempar ke luar angkasa. Kemudian gelombang kejut partikel2 nya mencapai planet kita dan terjadilah pembalikan kutub
Dengan kekuatan yang belum diketahui sinar matahari menyerang planet kita dan menyebabkan hubungan pendek yang besar. Itulah kebenaran besar di balik pembalikan kutub bumi. Tapi bagaiana kita secara ilmiah menggambarkan fakta ini? Apa penyebab fisik secara pasti yang menyebabkan pembalikan kutub matahari ini?
Badai Matahari Penyebab Kutub Bergeser
Dalam buku Earth Under Fire, saya membawa sebuah teori yang benar. Tepatnya pada bab yang berjudul Solar Storms and Geomagnetic Flips. Seorang ahli astronomi Paul la Violette menulis “perputaran medan magnet telah dibuktikan melalui eksperimen. Dengan menembakkan partikel dalam jumlah besar ke magnet bipolar (yg memiliki 2 kutub). Partikel2 ini ditangkap pada medan magnet dan menyebabkan ‘ring-stream’ (aliran cincin) pada magnet tersebut. Pada saat tertentu aliran ini kecepatannya bertambah besar sampai medan magnet berbalik secara total”
Dalam skenario yang sama medan magnet bumi dapat berbalik dengan cara yang sama. Para ahli astronomi tahu bahwa badai partikel matahari dapat menekan medan magnet bumi dan menaikkan kekuatannya secara bertahap.
Ketika partikel matahari mencapai bumi, partikel2 elektromagnetis akan bergerak dalam lintasan spiral sepanjang garis magnetis ; dari kutub utara sampai kutub selatan dan balik lagi. Ketika melewati poros utara-selatan, partikel2 itu akan bergerak ke arah garis katulistiwa. Ketika sampai di situ partikel2 itu akan bergabung dan membentuk sebuah cincin arus yang super kuat.
Cincin arus menghasilkan medan magnet yang hebat yang berlawanan dengan medan magnet bumi. Untuk menghadang medan magnet bumi, kita memerlukan sinar matahari yang ratusan kali lebih kuat daripada yang terkuat dari yang pernahkita lihat sekarang. Pada pembalikan medan magnet matahari pada derajat ini akan dicapai.
Mulai dari sini, sudut pandang saya mulai berbeda dengan pendapat Paul La Violette. Bukan saja akan terjadi pembalikan kutub, tapi bumi akan mulai berputar pada arah yang sebaliknya. Ini dapat terjadi ketika cincin arus menekan inti bumi di arah yang berlawanan.
Semua orang tahu bahwa ketika kita merubah kutub elektrik motor, motor tersebut akan belok menuju arah yang lain. Hal ini juga berlaku bagi bumi. Ketika ada hubungan pendek dari luar, inti bumi tidak dapat berbuat apa2 selain berputar pada arah sebaliknya.
Pembinasaan dan Kehidupan Baru
Bencana ini tidak hanya berakibat pada kehancuran besar pada kehidupan di bumi, namun juga pada kelanjutan eksistensinya. Bagaimanapun juga ini terdengar susah untuk dipahami. Begini penjelasannya. Medan magnet bumi tidak terjadi secara alami. Fungsi utamanya adalah untuk melindungi kita dari radiasi kosmik sinar matahari. Tanpa medan magnet ini, kehidupan secara praktis merupakan sesuatu yang mustahil, kehidupan di planet kita akan musnah. Semua akan terbakar, radiasi radioaktif mematikan akan mendera permukaan bumi
Jadi sekarang kita akan berbicara mengenai dualitas yang tidak kompatibel: di samping banyak mahluk hidup yang akan musnah, kehidupan juga terus akan berjalan, karena batere bumi yang sudah terlalu lelah akan diisi ulang oleh sinar matahari. Selama ribuan tahun medan magnet bumi akan menjadi stabil, melindungi tumbuhan dan hewan dari radiasi yang merusak. Ketika melakukan ini batere bumi akan habis kembali dan siklus kehancuran lain akan mengikuti diikuti dengan penciptaan dan mutasi baru.
http://2012era.blogspot.com
Diposkan oleh I.N.D.I.G.O di 00:25
Reaksi:
Label: 2012 era, mystery
2 komentar:
Pakmul mengatakan…
Di antara tanda-tanda kiamat sudah dekat adalah daratan arab akan menjadi padang rumput yang subur, banyak terjadi gempa bumi, lapisan bumi banyak yang pecah dan mengeluarkan asap dari inti bumi. Pada hari H nya adalah matahari terbit dari sebelah barat.
Semua itu disebabkan hanya satu yaitu : “Kutub bergeser” mendekati jazirah Arab sehingga disana menjadi banyak air, padang rumput dan subur.
Bumi akan mengalami perubahan bentuk permukaan karena “Gaya sentrifugal” akan berubah jika kutub bergeser. Ingat bumi kita agak ellips/lonjong karena sentrifugal di katulistiwa. Jika kutub bergeser maka katulistiwa akan bergeser dan gaya sentrifugal akan bergeser, maka bentuk bumi lonjong arah horisontal akan berubah lonjong vertikal dan itu menyebabkan gempa bumi yang dahsyat serta banyak lapisan yang retak dan pecah hingga inti bumi menyemburkan asap dimana-mana.
Dan yang terakhir “hari H kiamat” adalah kutub utara berubah jadi kutub selatan (atau sebaliknya) maka matahari akan terbit dari sebelah Barat. Kondisi alam semesta tidak lagi setabil, lintasan bumi akan semakin kacau, bulan akan tertarik gravitasi bumi dan jatuh ke bumi. Kehancuran total akan dimulai. “KIAMAT TELAH TIBA”.
Jangan lupa Simak dan Fikirkan “tanda-tanda kiamat Versi Nabi Muhammad SAW.”, semuanya dapat dijelaskan secara ilmiah!
Tapi jangan pernah bilang kiamat datang tahun 2012, karena semua itu hanya perkiraan saja, dan pastinya tidak ada yang tahu!!!
20 November 2009 22:28
Anonim mengatakan…
Setuju..kiamat pasti datang tapi tak ada yang bisa menentukan kapan pastinya akan terjadi kecuali Allah…
31 Desember 2009 08:28
2012: No Killer Solar Flare
June 21st, 2008
Written by Ian O’Neill ShareThis
Could a solar flare destroy the Earth in 2012?
We could be in for a huge firework display in 2012. The Sun will be approaching the peak of its 11-year cycle, called “solar maximum”, so we can expect a lot of solar activity. Some predictions put the solar maximum of Solar Cycle 24 even more energetic than the last solar maximum in 2002-2003 (remember all those record breaking X-class flares?). Solar physicists are already getting excited about this next cycle and new prediction methods are being put to good use. But should we be worried?
Related 2012 articles:
* 2012: No Geomagnetic Reversal (posted October 3rd 2008)
* 2012: No Killer Solar Flare (posted June 21st 2008)
* 2012: Planet X Is Not Nibiru (posted June 19th 2008)
* 2012: No Planet X (posted May 25th 2008)
* No Doomsday in 2012 (posted May 19th 2008)
According to one of the many Doomsday scenarios we have been presented with in the run-up to the Mayan Prophecy-fuelled “end of the world” in the year 2012, this scenario is actually based on some science. What’s more, there may be some correlation between the 11-year solar cycle and the time cycles seen in the Mayan calendar, perhaps this ancient civilization understood how the Sun’s magnetism undergoes polarity changes every decade or so? Plus, religious texts (such as the Bible) say that we are due for a day of judgement, involving a lot of fire and brimstone. So it looks like we are going to get roasted alive by our closest star on December 21st, 2012!
Before we go jumping to conclusions, take a step back and think this through. Like most of the various ways the world is going to end in 2012, the possibility of the Sun blasting out a huge, Earth-damaging solar flare is very attractive to the doomsayers out there. But let’s have a look at what really happens during an Earth-directed solar flare event, the Earth is actually very well protected. Although some satellites may not be…
The Earth has evolved in a highly radioactive environment. The Sun constantly fires high-energy particles from its magnetically dominated surface as the solar wind. During solar maximum (when the Sun is at its most active), the Earth may be unlucky enough to be staring down the barrel of an explosion with the energy of 100 billion Hiroshima-sized atomic bombs. This explosion is known as a solar flare and the effects of which can cause problems here on Earth.
Before we look at the Earth-side effects, let’s have a look at the Sun and briefly understand why it gets so angry every 11 years or so.
The Solar Cycle
A comparison between solar min and solar max with a diagram below. NASA/SOHO (top), Ian O’Neill (bottom)
First and foremost, the Sun has a natural cycle with a period of approximately 11 years. During the lifetime of each cycle, the magnetic field lines of the Sun are dragged around the solar body by differential rotation at the solar equator. This means that the equator is spinning faster than the magnetic poles. As this continues, solar plasma drags the magnetic field lines around the Sun, causing stress and a build up of energy (an illustration of this is pictured). As magnetic energy increases, kinks in the magnetic flux form, forcing them to the surface. These kinks are known as coronal loops which become more numerous during periods of high solar activity.
This is where the sunspots come in. As coronal loops continue to pop up over the surface, sunspots appear too, often located at the loop footpoints. Coronal loops have the effect of pushing the hotter surface layers of the Sun (the photosphere and chromosphere) aside, exposing the cooler convection zone (the reasons why the solar surface and atmosphere is hotter than the solar interior is down to the coronal heating phenomenon). As magnetic energy builds up, we can expect more and more magnetic flux to be forced together. This is when a phenomenon known as magnetic reconnection occurs.
Reconnection is the trigger for solar flares of various sizes. As previously reported, solar flares from “nanoflares” to “X-class flares” are very energetic events. Granted, the largest flares my generate enough energy for 100 billion atomic explosions, but don’t let this huge figure concern you. For a start, this flare occurs in the low corona, right near the solar surface. That’s nearly 100 million miles away (1AU). The Earth is nowhere close to the blast.
As the solar magnetic field lines release a huge amount of energy, solar plasma is accelerated and confined within the magnetic environment (solar plasma is superheated particles like protons, electrons and some light elements such as helium nuclei). As the plasma particles interact, X-rays may be generated if the conditions are right and bremsstrahlung is possible. (Bremsstrahlung occurs when charged particles interact, resulting in X-ray emission.) This may create an X-ray flare.
The Problem with X-ray Solar Flares
SOHO EIT image of a record breaking solar flare (SOHO/NASA)
The biggest problem with an X-ray flare is that we get little warning when it is going to happen as X-rays travel at the speed of light (one of the record breaking 2003 solar flares is pictured left). X-rays from an X-class flare will reach the Earth in around eight minutes. As X-rays hit our atmosphere, they are absorbed in the outermost layer called the ionosphere. As you can guess from the name, this is a highly charged, reactive environment, full of ions (atomic nuclei, and free electrons).
During powerful solar events such as flares, rates of ionization between X-rays and atmospheric gases increase in the D and E region layers of the ionosphere. There is a sudden surge in electron production in these layers. These electrons can cause interference to the passage of radio waves through the atmosphere, absorbing short wave radio signals (in the high frequency range), possibly blocking global communications. These events are known as “Sudden Ionospheric Disturbances” (or SIDs) and they become commonplace during periods of high solar activity. Interestingly, the increase in electron density during a SID boosts the propagation of Very Low Frequency (VLF) radio, a phenomenon scientists use to measure the intensity of X-rays coming from the Sun.
Coronal Mass Ejections?
A CME in 2007 (SOHO/NASA)
X-ray solar flare emissions are only part of the story. If the conditions are right, a coronal mass ejection (CME) might be produced at the site of the flare (although either phenomenon can occur independently). CMEs are slower than the propagation of X-rays, but their global effects here on Earth can be more problematic. They may not travel at the speed of light, but they still travel fast; they can travel at a rate of 2 million miles per hour (3.2 million km/hr), meaning they may reach us in a matter of hours.
This is where much effort is being put into space weather prediction. We have a handful of spacecraft sitting between the Earth and the Sun at the Earth-Sun Lagrangian (L1) point with sensors on board to measure the energy and intensity of the solar wind. Should a CME pass through their location, energetic particles and the interplanetary magnetic field (IMF) can be measured directly. One mission called the Advanced Composition Explorer (ACE) sits in the L1 point and provides scientists with up to an hour notice on the approach of a CME. ACE teams up with the Solar and Heliospheric Observatory (SOHO) and the Solar TErrestrial RElations Observatory (STEREO), so CMEs can be tracked from the lower corona into interplanetary space, through the L1 point toward Earth. These solar missions are actively working together to provide space agencies with advanced notice of an Earth-directed CME.
So what if a CME reaches Earth? For a start, much depends on the magnetic configuration of the IMF (from the Sun) and the geomagnetic field of the Earth (the magnetosphere). Generally speaking, if both magnetic fields are aligned with polarities pointing in the same direction, it is highly probable that the CME will be repelled by the magnetosphere. In this case, the CME will slide past the Earth, causing some pressure and distortion on the magnetosphere, but otherwise passing without a problem. However, if the magnetic field lines are in an anti-parallel configuration (i.e. magnetic polarities in opposite directions), magnetic reconnection may occur at the leading edge of the magnetosphere.
In this event, the IMF and magnetosphere will merge, connecting the Earth’s magnetic field with the Sun’s. This sets the scene for one of the most awe inspiring events in nature: the aurora.
Satellites in Peril
As the CME magnetic field connects with the Earth’s, high energy particles are injected into the magnetosphere. Due to solar wind pressure, the Sun’s magnetic field lines will fold around the Earth, sweeping behind our planet. The particles injected in the “dayside” will be funnelled into the polar regions of the Earth where they interact with our atmosphere, generating light as aurorae. During this time, the Van Allen belt will also become “super-charged”, creating a region around the Earth that could cause problems to unprotected astronauts and any unshielded satellites. For more on the damage that can be caused to astronauts and spacecraft, check out “Radiation Sickness, Cellular Damage and Increased Cancer Risk for Long-term Missions to Mars” and “New Transistor Could Side-Step Space Radiation Problem.”
As if the radiation from the Van Allen belt wasn’t enough, satellites could succumb to the threat of an expanding atmosphere. As you’d expect, as if the Sun hits the Earth with X-rays and CMEs, there will be inevitable heating and global expansion of the atmosphere, possibly encroaching into satellite orbital altitudes. If left unchecked, an aerobraking effect on satellites could cause them to slow and drop in altitude. Aerobraking has been used extensively as a space flight tool to slow spacecraft down when being inserted into orbit around another planet, but this will have an adverse effect on satellites orbiting Earth as any slowing of velocity could cause it to re-enter the atmosphere.
We Feel the Effects on the Ground Too
Sensitive to solar activity? Power grids on the ground (AP Photo/Smithsonian)
Although satellites are on the front line, if there is a powerful surge in energetic particles entering the atmosphere, we may feel the adverse effects down here on Earth too. Due to the X-ray generation of electrons in the ionosphere, some forms of communication may become patchy (or be removed all together), but this isn’t all that can happen. Particularly in high-latitude regions, a vast electric current, known as an “electrojet”, may form through the ionosphere by these incoming particles. With an electric current comes a magnetic field. Depending on the intensity of the solar storm, currents may be induced down here on the ground, possibly overloading national power grids. On March 13th 1989, six million people lost power in the Quebec region of Canada after a huge increase in solar activity caused a surge from ground-induced currents. Quebec was paralysed for nine hours whilst engineers worked on a solution to the problem.
Can Our Sun Produce a Killer Flare?
Artist impression of a huge flare on red dwarf star EV Lacertae observed by the Swift observatory (NASA)
The short answer to this is “no”.
The longer answer is a little more involved. Whilst a solar flare from out Sun, aimed directly at us, could cause secondary problems such as satellite damage and injury to unprotected astronauts and blackouts, the flare itself is not powerful enough to destroy Earth, certainly not in 2012. I dare say, in the far future when the Sun begins to run out of fuel and swell into a red giant, it might be a bad era for life on Earth, but we have a few billion years to wait for that to happen. There could even be the possibility of several X-class flares being launched and by pure bad luck we may get hit by a series of CMEs and X-ray bursts, but none will be powerful to overcome our magnetosphere, ionosphere and thick atmosphere below.
“Killer” solar flares have been observed on other stars. In 2006, NASA’s Swift observatory saw the largest stellar flare ever observed 135 light-years away. Estimated to have unleashed an energy of 50 million trillion atomic bombs, the II Pegasi flare will have wiped out most life on Earth if our Sun fired X-rays from a flare of that energy at us. However, our Sun is not II Pegasi. II Pegasi is a violent red giant star with a binary partner in a very close orbit. It is believed the gravitational interaction with its binary partner and the fact II Pegasi is a red giant is the root cause behind this energetic flare event.
Doomsayers point to the Sun as a possible Earth-killer source, but the fact remains that our Sun is a very stable star. It does not have a binary partner (like II Pegasi), it has a predictable cycle (of approximately 11 years) and there is no evidence that our Sun contributed to any mass extinction event in the past via a huge Earth-directed flare. Very large solar flares have been observed (such as the 1859 Carrington white light flare)… but we are still here.
In an added twist, solar physicists are surprised by the lack of solar activity at the start of this 24th solar cycle, leading to some scientists to speculate we might be on the verge of another Maunder minimum and “Little Ice Age”. This is in stark contrast to NASA solar physicist’s 2006 prediction that this cycle will be a “doozy”.
This leads me to conclude that we still have a long way to go when predicting solar flare events. Although space weather prediction is improving, it will be a few years yet until we can read the Sun accurately enough to say with any certainty just how active a solar cycle is going to be. So, regardless of prophecy, prediction or myth, there is no physical way to say that the Earth will be hit by any flare, let alone a big one in 2012. Even if a big flare did hit us, it will not be an extinction event. Yes, satellites may be damaged, causing secondary problems such as a GPS loss (which might disrupt air traffic control for example) or national power grids may be overwhelmed by auroral electrojets, but nothing more extreme than that.
But hold on, to sidestep this issue, doomsayers now tell us that a large solar flare will hit us just as the Earth’s geomagnetic field weakens and reverses, leaving us unprotected from the ravages of a CME… The reasons why this is not going to happen in 2012 is worthy of its own article. So, look out for the next 2012 article “2012: No Geomagnetic Reversal”.
Leading image credits: MIT (supernova simulation), NASA/JPL (solar active region in EUV). Effects and editing: myself.
F 151 C4
Anak IPA pada ngeluh belajar Fisika. Ilmu fisika memang beda dengan ilmu matematika, kimia apalagi biologi. Butuh konsentrasi, ketekunan dan waktu untuk bisa memahaminya. Walaupun terkesan rumit, tapi enjoy aja. Gak usah dibawa stress. Kalau sudah belajar tapi nilainya jelek, tinggal menyiapkan remedial. Lagian soal remedial itu kan mirip dengan soal ulangan. Tugas-mu hanya menghafal cara penyelesaian untuk bentuk soal tertentu, paling cuma 5 soal. Massa sih hafalin 5 rumus aja gak bisa?…
Kalo kamu udah nganggap susah, ibaratnya otak kamu dah nolak tiap kali mau belajar fisika. Mau dijejelin kayak apapun, gak akan bisa masuk. Jadi gak usah benci2 amat, biasa aja lagi…seandanyai kamu tetep gak bisa menaklukan tuh pelajaran walupun dan belajar mati2an, berarti memang itulah batas kemampuan yang ada. Dinikmati aja, tanpa harus melaknat tuh pelajaran. Biar gitu juga, karena ada yang mau belajar fisika and science, teknologi bisa tambah canggih dan kita2 adalah penikmatnya sekarang…
So, pesen ku buat anak2 sma 5, fisika gak usah dibuat stress. Yang penting tunjukkan keseriusan dalam belajar dan menuntut ilmu. Kalopun fisika selalu jadi anggota remedial club, ya jalani aja…asalkan ada persiapan remedial pasti bisa.
‘Fish technology’ draws renewable energy from slow water currents
Published: Friday, November 21, 2008 – 12:22 in Physics & Chemistry
Scott Galvin
Slow-moving ocean and river currents could be a new, reliable and affordable alternative energy source. A University of Michigan engineer has made a machine that works like a fish to turn potentially destructive vibrations in fluid flows into clean, renewable power. The machine is called VIVACE. A paper on it is published in the current issue of the quarterly Journal of Offshore Mechanics and Arctic Engineering.
VIVACE is the first known device that could harness energy from most of the water currents around the globe because it works in flows moving slower than 2 knots (about 2 miles per hour.) Most of the Earth’s currents are slower than 3 knots. Turbines and water mills need an average of 5 or 6 knots to operate efficiently.
VIVACE stands for Vortex Induced Vibrations for Aquatic Clean Energy. It doesn’t depend on waves, tides, turbines or dams. It’s a unique hydrokinetic energy system that relies on “vortex induced vibrations.”
Vortex induced vibrations are undulations that a rounded or cylinder-shaped object makes in a flow of fluid, which can be air or water. The presence of the object puts kinks in the current’s speed as it skims by. This causes eddies, or vortices, to form in a pattern on opposite sides of the object. The vortices push and pull the object up and down or left and right, perpendicular to the current.
These vibrations in wind toppled the Tacoma Narrows bridge in Washington in 1940 and the Ferrybridge power station cooling towers in England in 1965. In water, the vibrations regularly damage docks, oil rigs and coastal buildings.
“For the past 25 years, engineers—myself included—have been trying to suppress vortex induced vibrations. But now at Michigan we’re doing the opposite. We enhance the vibrations and harness this powerful and destructive force in nature,” said VIVACE developer Michael Bernitsas, a professor in the U-M Department of Naval Architecture and Marine Engineering.
Fish have long known how to put the vortices that cause these vibrations to good use. “VIVACE copies aspects of fish technology,” Bernitsas said. “Fish curve their bodies to glide between the vortices shed by the bodies of the fish in front of them. Their muscle power alone could not propel them through the water at the speed they go, so they ride in each other’s wake.”
This generation of Bernitsas’ machine looks nothing like a fish, though he says future versions will have the equivalent of a tail and surface roughness a kin to scales. The working prototype in his lab is just one sleek cylinder attached to springs. The cylinder hangs horizontally across the flow of water in a tractor-trailer-sized tank in his marine renewable energy laboratory. The water in the tank flows at 1.5 knots.
Here’s how VIVACE works: The very presence of the cylinder in the current causes alternating vortices to form above and below the cylinder. The vortices push and pull the passive cylinder up and down on its springs, creating mechanical energy. Then, the machine converts the mechanical energy into electricity.
Just a few cylinders might be enough to power an anchored ship, or a lighthouse, Bernitsas says. These cylinders could be stacked in a short ladder. The professor estimates that array of VIVACE converters the size of a running track and about two stories high could power about 100,000 houses. Such an array could rest on a river bed or it could dangle, suspended in the water. But it would all be under the surface.
Because the oscillations of VIVACE would be slow, it is theorized that the system would not harm marine life like dams and water turbines can.
Bernitsas says VIVACE energy would cost about 5.5 cents per kilowatt hour. Wind energy costs 6.9 cents a kilowatt hour. Nuclear costs 4.6, and solar power costs between 16 and 48 cents per kilowatt hour depending on the location.
“There won’t be one solution for the world’s energy needs,” Bernitsas said. “But if we could harness 0.1 percent of the energy in the ocean, we could support the energy needs of 15 billion people.”
The researchers recently completed a feasibility study that found the device could draw power from the Detroit River. They are working to deploy one for a pilot project there within the 18 months.
Source: University of Michigan
Kejadian Alam
|
|
| © 2008 Media Indonesia. All rights reserved. |
