100 years ago today: KABLAM!!!!!

The entire universe in blog form
June 30 2008 12:02 AM

100 years ago today: KABLAM!!!!!

Two notes: Commenting on the blog will be turned off after 14:00 UT today for a major blog upgrade. Also, an article is in USA Today, um, today, about the topic of this post, and I'm quoted in it.

100 years ago today, a small chunk of rock or possibly ice was lazily making its way across the inner solar system when a large, blue-green planet got in its way. Traveling roughly westward, it entered the Earth's atmosphere moving at tens of thousands kilometers per hour. Compressed and battered by tremendous forces, the object got about 5 - 10 kilometers from the ground before it succumbed, exploding like a gigantic multi-megaton bomb.

The air blast flattened trees for hundreds of square kilometers. The ground shook, witnesses felt the hellish heat from kilometers away, and the shock wave circled the world. It happened over the remote Podkammenaya Tungus river, a swampy region in Russia; had it happened over Moscow a million people might have died within minutes.

Now known as the Tunguska Event, it stands today as a shocking reminder that we live in a cosmic shooting gallery, and the Earth sits in the crosshairs of many objects.

The event has been studied extensively. An expedition to the region revealed no crater, to the surprise of those early 20th century scientists. This was the first clue that it was an air blast. No debris has ever been conclusively identified as extraterrestrial, leading to some debate over whether it was a rocky asteroid or an icy bit of comet. Some asteroids are like rubble piles, pulverized by impacts as they orbit the Sun; these are fragile objects that would more easily explode in the air. I've often wondered if this would explain the situation.

The past century has seen many changes in the way we do astronomy, and how we hunt for dangerous rocks. Automated surveys scan the heavens, tirelessly looking out for bullets with our name on them. Astronomers model the impactors and impacts, looking for ways to understand them better. Scientists propose physically going to asteroids with robotic and manned missions, to get far better data on them.

All of this is more than just scientific curiosity: our survival as a species may depend on it. And that's no exaggeration.

So I congratulate those who study these killers, and who look to our future -- and here I will call out my personal friend Dan Durda who is very concerned indeed, and has devoted his career to them. I applaud the B612 Foundation, which is devoted to mitigating this danger. And I especially stand up and point to Congress -- including my own Representative Mark Udall -- which has the foresight to mandate that NASA look into the dangers from the Near Earth Asteroid Apophis. I wrote about this extensively in my book Death from the Skies!, and I learned far more than I wanted to about what happened over Tunguska. I'm very glad others are taking this threat seriously.

We've come a long way since that hot, muggy Russian morning on June 30, 1908. And let's be clear: if another Tunguska-class object had its sights set on us, we wouldn't know it until we, like those Russians, saw a flash of terrible light in our sky, felt the burning heat, and were knocked down by the blast.

The odds of it happening any time soon are low, very low. I don't lose any sleep over it -- I'm not worried, I'm concerned. But this anniversary is a sobering reminder that it can happen again, and it will, unless we do something about it.

Artwork credit: the fantastic space artist Don Davis. Used by permission.

 

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

TODAY IN SLATE

War Stories

The Right Target

Why Obama’s airstrikes against ISIS may be more effective than people expect.

The One National Holiday Republicans Hope You Forget

It’s Legal for Obama to Bomb Syria Because He Says It Is

I Stand With Emma Watson on Women’s Rights

Even though I know I’m going to get flak for it.

Should You Recline Your Seat? Two Economists Weigh In.

Doublex

It Is Very, Very Stupid to Compare Hope Solo to Ray Rice

Or, why it is very, very stupid to compare Hope Solo to Ray Rice.

Building a Better Workplace

In Defense of HR

Startups and small businesses shouldn’t skip over a human resources department.

Why Is This Mother in Prison for Helping Her Daughter Get an Abortion?

Use Facebook to Reconnect With Old Friends, Share Photos, and Serve People With Legal Papers

  News & Politics
Foreigners
Sept. 23 2014 6:40 PM Coalition of the Presentable Don’t believe the official version. Meet America’s real allies in the fight against ISIS.
  Business
Moneybox
Sept. 23 2014 2:08 PM Home Depot’s Former Lead Security Engineer Had a Legacy of Sabotage
  Life
Outward
Sept. 23 2014 1:57 PM Would a Second Sarkozy Presidency End Marriage Equality in France?
  Double X
The XX Factor
Sept. 23 2014 2:32 PM Politico Asks: Why Is Gabby Giffords So “Ruthless” on Gun Control?
  Slate Plus
Political Gabfest
Sept. 23 2014 3:04 PM Chicago Gabfest How to get your tickets before anyone else.
  Arts
Brow Beat
Sept. 23 2014 4:45 PM Why Is Autumn the Only Season With Two Names?
  Technology
Future Tense
Sept. 23 2014 5:36 PM This Climate Change Poem Moved World Leaders to Tears Today
  Health & Science
Science
Sept. 23 2014 4:33 PM Who Deserves Those 4 Inches of Airplane Seat Space? An investigation into the economics of reclining.
  Sports
Sports Nut
Sept. 23 2014 7:27 PM You’re Fired, Roger Goodell If the commissioner gets the ax, the NFL would still need a better justice system. What would that look like?