Objek dari langit meletup di Siberia dan boleh didengari sejauh hampir 800 kilom

FOTHER-MUCKER · Post time 7-8-2020 08:09 AM

Objek dari langit meletup di Siberia

LETUPAN dahsyat di Tunguska pada 30 Jun 1908 dikatakan kedengaran sejauh 800 kilometer dari lokasi.

PADA 30 Jun 1908, sekitar jam 7 pagi, satu objek misteri jatuh dari langit dan menghempap satu kawasan di Siberia.

Kesan hentaman itu menimbulkan satu letupan yang teramat dahsyat dalam sejarah dunia ketika itu. Tidak pernah manusia menyaksikan letupan sedahsyat itu malah bom atom masih belum dicipta ketika objek berkenaan menghempap Bumi.

Objek misteri itu pada mulanya dikesan muncul dari atmosfera di barat China dan menuju ke utara melewati kawasan tengah Russia bersama bunyi berdesing yang teramat kuat.

Seterusnya pada jam 7.17 pagi, berdekatan Sungai Stony Tunguska, satu letupan teramat kuat meletus sehinggakan alat seismograf yang terletak di Irkutsk iaitu hampir 900 kilometer dari lokasi letupan mencatatkan bacaan gempa bumi. Gegaran turut direkodkan sehingga ke Washington, Amerika Syarikat.

Di pekan Vanavara yang terletak sekitar 60 kilometer dari lokasi letupan, penduduknya melambung ke udara manakala bumbung rumah runtuh dan cermin tingkap berkecai akibat gegaran itu. Penduduk yang berada berdekatan lokasi letupan pula pekak dipalu bunyi guruh yang boleh didengari sejauh hampir 800 kilometer.

Selepas gegaran itu berakhir, kawasan sekitar Tunguska dihujani `hujan hitam' hasil kotoran dan serpihan yang bertebaran akibat letupan itu. Apa yang pelik adalah letupan dahsyat itu tidak mengorbankan sebarang nyawa manusia.

Walaupun kejadian itu amat menggemparkan, tiada siapa di kalangan saintis yang tampil mengkaji fenomena berkenaan.

SAINTIS Russia, Leonid Kulik.

Sehinggalah 13 tahun kemudian iaitu pada 1921, seorang saintis Russia, Leonid Kulik, terbaca mengenai letupan aneh di Tunguska itu dalam akhbar lama. Tertarik dengan enigma yang menyelubungi letupan itu menyebabkan dia berusaha menjejaki lokasi hentaman objek misteri berkenaan.

Akhirnya selepas enam tahun mencari, pada 13 April 1927, Kulik berdiri di tebing Sungai Makirta dan melihat sendiri betapa luasnya kawasan yang musnah dihentam objek yang dipercayainya sebagai batu meteor itu.

Di hadapannya, tanah seluas kira-kira 70 kilometer mendap menjadi bujur dan banyak kesan pohon hutan lama yang tercabut dan terbakar. Dia turun ke kawasan mendap itu dengan harapan dapat mencari kawah akibat hentaman selain batu meteor itu sendiri.

Bagaimanapun, selepas lama mencari, dia tidak menemui apa yang diharapkan sebaliknya menjumpai kawasan hutan aneh di mana pohonnya berdiri tegak seumpama tiang telefon tanpa dahan. Dia mencari lagi tetapi batu meteor itu gagal ditemuinya di mana-mana.

Kepulangan Kulik bersama laporan mengejutkan itu seterusnya menimbulkan pelbagai persoalan membingungkan di kalangan saintis mengenai punca letupan dahsyat itu.

Puluhan tahun kemudian, saintis Russia, Aleksander Kazansev mengemukakan keyakinannya bahawa letupan itu adalah sama kuatnya dengan letupan bom atom kerana ia menunjukkan ciri-ciri sama seperti letupan bom atom di Hiroshima, Jepun pada 1945.

Antaranya pokok tanpa dahan dan berdiri tegak seperti tiang telefon turut ditemui di Hiroshima selepas dibom Amerika Syarikat. Awam berbentuk cendawan dan hujan hitam selain gegaran seumpama gempa bumi yang berlaku di Tunguska turut berlaku di Hiroshima ketika itu.

KEADAAN hutan selepas letupan dahsyat di Tunguska pada 30 Jun 1908.

Akan tetapi, persoalan membingungkan adalah bom atom masih belum dicipta ketika itu, justeru apakah objek yang mampu menghasilkan letupan yang sama dahsyatnya di Tunguska itu?

Tanpa sebarang penemuan, hanya pelbagai teori yang dikemukakan, antaranya ia mungkin komet yang berasal daripada gas dan bukannya batu meteor selain batu meteor itu mungkin berkecai di udara.

Teori lain adalah ia mungkin meteor anti jirim, lubang hitam mini yang melalui Bumi selain kapal angkasa makhluk asing yang terhempas di Bumi.

Ada juga teori bahawa objek misteri itu mungkin punca kepupusan dinosaur selain mencetuskan letupan ala nuklear pada zaman India kuno seperti tertera dalam epik Mahabharata dan Ramayana.

Akan tetapi sehingga kini, tiada siapa yang mengetahui apakah objek itu sebenarnya sekali gus meninggalkan kejadian letupan aneh di Siberia itu kekal misteri.

FAKTA: Letupan di Tunguska

Berlaku pada 30 Jun 1908, sekitar jam 7 pagi.
Objek misteri dikesan muncul dari atmosfera di barat China sebelum terhempas di Tunguska.
Alat seismograf di Irkutsk iaitu hampir 900 kilometer dari lokasi letupan mencatat bacaan gempa bumi.
Gegaran turut direkodkan sehingga ke Washington, Amerika Syarikat.
Penduduk pekan Vanavara yang terletak sekitar 60 kilometer dari lokasi letupan, melambung ke udara.
Letupan kedengaran sejauh hampir 800 kilometer dari lokasi.
Tanah seluas kira-kira 70 kilometer mendap menjadi bujur dan banyak kesan pohon hutan lama yang tercabut dan terbakar.
Kekuatan sama dengan letupan bom atom di Hiroshima, Jepun pada 1945

FOTHER-MUCKER · Post time 7-8-2020 08:28 AM

Edited by FOTHER-MUCKER at 6-8-2020 04:30 PM

The Tunguska Impact--100 Years Later

The Tunguska Event

June 30, 2008: The year is 1908, and it's just after seven in the morning. A man is sitting on the front porch of a trading post at Vanavara in Siberia. Little does he know, in a few moments, he will be hurled from his chair and the heat will be so intense he will feel as though his shirt is on fire.

That's how the Tunguska event felt 40 miles from ground zero.

Today, June 30, 2008, is the 100th anniversary of that ferocious impact near the Podkamennaya Tunguska River in remote Siberia--and after 100 years, scientists are still talking about it.

"If you want to start a conversation with anyone in the asteroid business all you have to say is Tunguska," says Don Yeomans, manager of the Near-Earth Object Office at NASA's Jet Propulsion Laboratory. "It is the only entry of a large meteoroid we have in the modern era with first-hand accounts."

Above: Trees felled by the Tunguska explosion. Credit: the Leonid Kulik Expedition. [more]

While the impact occurred in '08, the first scientific expedition to the area would have to wait for 19 years. In 1921, Leonid Kulik, the chief curator for the meteorite collection of the St. Petersburg museum led an expedition to Tunguska. But the harsh conditions of the Siberian outback thwarted his team's attempt to reach the area of the blast. In 1927, a new expedition, again lead by Kulik, reached its goal.

"At first, the locals were reluctant to tell Kulik about the event," said Yeomans. "They believed the blast was a visitation by the god Ogdy, who had cursed the area by smashing trees and killing animals."

While testimonials may have at first been difficult to obtain, there was plenty of evidence lying around. Eight hundred square miles of remote forest had been ripped asunder. Eighty million trees were on their sides, lying in a radial pattern.

"Those trees acted as markers, pointing directly away from the blast's epicenter," said Yeomans. "Later, when the team arrived at ground zero, they found the trees there standing upright – but their limbs and bark had been stripped away. They looked like a forest of telephone poles."

Such debranching requires fast moving shock waves that break off a tree's branches before the branches can transfer the impact momentum to the tree's stem. Thirty seven years after the Tunguska blast, branchless trees would be found at the site of another massive explosion – Hiroshima, Japan.

Kulik's expeditions (he traveled to Tunguska on three separate occasions) did finally get some of the locals to talk. One was the man based at the Vanara trading post who witnessed the heat blast as he was launched from his chair. His account:

Suddenly in the north sky… the sky was split in two, and high above the forest the whole northern part of the sky appeared covered with fire… At that moment there was a bang in the sky and a mighty crash… The crash was followed by a noise like stones falling from the sky, or of guns firing. The earth trembled.

The massive explosion packed a wallop. The resulting seismic shockwave registered with sensitive barometers as far away as England. Dense clouds formed over the region at high altitudes which reflected sunlight from beyond the horizon. Night skies glowed, and reports came in that people who lived as far away as Asia could read newspapers outdoors as late as midnight. Locally, hundreds of reindeer, the livelihood of local herders, were killed, but there was no direct evidence that any person perished in the blast.

Above: The location of the Tunguska impact.

"A century later some still debate the cause and come up with different scenarios that could have caused the explosion," said Yeomans. "But the generally agreed upon theory is that on the morning of June 30, 1908, a large space rock, about 120 feet across, entered the atmosphere of Siberia and then detonated in the sky."

It is estimated the asteroid entered Earth's atmosphere traveling at a speed of about 33,500 miles per hour. During its quick plunge, the 220-million-pound space rock heated the air surrounding it to 44,500 degrees Fahrenheit. At 7:17 a.m. (local Siberia time), at a height of about 28,000 feet, the combination of pressure and heat caused the asteroid to fragment and annihilate itself, producing a fireball and releasing energy equivalent to about 185 Hiroshima bombs.

"That is why there is no impact crater," said Yeomans. "The great majority of the asteroid is consumed in the explosion."

Yeomans and his colleagues at JPL's Near-Earth Object Office are tasked with plotting the orbits of present-day comets and asteroids that cross Earth's path, and could be potentially hazardous to our planet. Yeomans estimates that, on average, a Tunguska-sized asteroid will enter Earth's atmosphere once every 300 years.

"From a scientific point of view, I think about Tunguska all the time," he admits. Putting it all in perspective, however, "the thought of another Tunguska does not keep me up at night."

Editor: Dr. Tony Phillips | Credit: Science@NASA