Which cosmic event was the most spectacular (may be deadly)?

Answer 1

"was" means the question is asking about an event that has already happened, not one that will, could or might.

"spectacular" means striking, sensational (from m-w.com) and implies there is a spectator of some sort...an animal with eyes. That rules out the big bang, and other events that were not necessarily viewable by living beings, or, more specifically, by living beings on earth.

At first I thought I knew the answer: the meteor (then, meteorite after it hit) that created Chicxulub crater in Mexico's Yucatan peninsula, which marks the impact that may have ultimately killed the dinosaurs 65 million years ago.

Then I found this, about a meteor that created a crater more than twice the size of Chicxulub, and may have been responsible for the split-up of the Gondwana supercontinent!!

read on:

A meteor's roaring crash into Antarctica -- larger and earlier than the impact that killed the dinosaurs -- caused the biggest
mass extinction in Earth's history and likely spawned the Australian continent, scientists said.

Ohio State University scientists said the 483-kilometer-wide (300-mile-wide) crater is now hidden more than 1.6 kilometers (one mile) beneath the East Antarctic Ice Sheet.

"Gravity measurements that reveal its existence suggest that it could date back about 250 million years -- the time of the Permian-Triassic extinction, when almost all animal life on Earth died out," the university said in a statement Thursday.

"Its size and location -- in the Wilkes Land region of East Antarctica, south of Australia -- also suggest that it could have begun the breakup of the Gondwana supercontinent by creating the tectonic rift that pushed Australia northward," they added.

Scientists believe that the Permian-Triassic extinction paved the way for the dinosaurs to rise to prominence.

The Wilkes Land crater is more than twice the size of the Chicxulub crater in Mexico's Yucatan peninsula, which marks the impact that may have ultimately killed the dinosaurs 65 million years ago.

The Chicxulub meteor is thought to have been 9.6 kilometers (six miles) wide, while the Wilkes Land meteor could have been up to 48.3 kilometers (30 miles) wide -- four or five times wider.

"This Wilkes Land impact is much bigger than the impact that killed the dinosaurs, and probably would have caused catastrophic damage at the time," said Ralph von Frese, a professor of geological sciences at Ohio State.

He and Laramie Potts, a postdoctoral researcher in geological sciences, led the team that discovered the crater. They collaborated with other Ohio State and NASA scientists, as well as partners from Russia and South Korea.

They reported their preliminary results in a recent American Geophysical Union Joint Assembly meeting in Baltimore, Maryland.

Some 100 million years ago, Australia split from the ancient Gondwana supercontinent and began drifting north, pushed away by expansion of a rift valley into the eastern Indian Ocean.

The rift cuts directly through the crater, so the impact may have helped the rift to form, von Frese said.

Answer 2

You do not want a gamma ray burst going off in our neck of the woods. Believed to result from so-called hypernovas. Biggest pop since the first one.

Edit: Regarding Glenn's lecture below on what your question means, GRBs go off all the time, but fortunately are far enough away so we have to use scopes to see them. That doesn't mean they are not spectacular.

While we're throwing out opinions, the term "cosmic event" generally refers to something a bit more large-scale than a big rock hitting our planet. However, perhaps some bacteria with photo receptors enjoyed viewing the collision that eventually formed our moon.

Answer 3

On 4th July 1054, there had been a spectacular event of supernova seen by Indian sub/continent about which records of American-indian rock paintings and a record of Middle East physician exist. more information in the source given.
VR

Answer 4

The BIG BANG - if it wasn't for the Big Bang, we wouldn't be banging away on our PC's right now. I think that's pretty spectacular.

Answer 5

Meteor crashing to earth.