comets-book

You can now buy the recently released book, Fall of a Thousand Suns: How Near Misses and Comet Impacts affected the Religious Beliefs of our Ancestors. It is available through iBooks and Amazon.

 

This website only lists information on modern-day comets and meteor showers. The book, however, thoroughly investigates how specific ancient impacts and near misses changed religious beliefs around the world.

Comet Shoemaker-Levy 9

Comet Shoemaker-Levy 9

 

The Discovery of Comet Shoemaker-Levy 9 (D/1993 F2)

On March 24, 1993 Carolyn Shoemaker, Eugene Shoemaker and David Levy captured a fragmented comet in the night sky.  Now before you run out and buy a $400 telescope with hopes of having a comet named after you, it’s only fair to let you know the trio spotted this, their eleventh, comet using a telescope with an 18” mirror while on top of Palomar Mountain in California.

 

It was named Shoemaker-Levy (D/1993 F2). 

 

 

 

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Comet Shoemaker-Levy 9 Impact on Jupiter

Astrophysicists at the Jet Propulsion Laboratory ran some calculations and were stunned to discover the Shoemaker-Levy 9 Comet was in a death spiral, orbiting Jupiter roughly once every two years.  They believed, less than a year before Shoemaker-Levy 9 was spotted, the comet’s nucleus was torn into twenty-one pieces when it passed too close to Jupiter and its moons.  Sometime between 1929 and 1972, the comet was first captured by Jupiter’s gravitational pull.

 

Comet Shoemaker-Levy 9 Marks on Jupiter
Marks show the locations of where fragments tore through the Jovian atmosphere. Credit: Hubble Space Telescope Comet Team and NASA

As the Shoemaker-Levy 9 Comet appeared to be nearing the end of its life, predictions ran wild.  Smart astrophysicists played it close to the vest, however.  Why risk their reputation with wild predictions?  A comet impact had never been observed in human history.

 

Only one thing was a near certainty.  Beginning on July 16, 1994 the first of twenty-one fragments would slam into Jupiter.  Unfortunately, the impacts would be on the far side of the planet, unseen from Earth.  Not to fear.  Thanks to the incessant tinkering and ingenuity of humanity, the Wright Brothers’ 1903 biplane had morphed into satellites buzzing throughout the solar system in less than one lifetime.  As a result, NASA employees pecked at a keyboard on Earth, causing three satellites hundreds of millions of miles away to focus on the far side of Jupiter.  These satellites, Galileo, Ulysses and Voyager 2, were 148 million, 242 million and over 4 billion miles from Jupiter.  With satellites and telescopes trained on the largest planet in our solar system, it was time to wait.

 

The first fragment, Fragment A, believed to be around 1,476 feet (450 m) in diameter, hit Jupiter at 133,000 miles (214,042 km) an hour on July 16, 1994.  Speeds like that are almost impossible to process, so let’s break it down a little.  It’s 2,217 miles a minute, which means Shoemaker-Levy 9 could travel from Chicago to Los Angeles in 55 seconds. Galileo sent back pictures of Fragment A as it exploded in Jupiter’s atmosphere sending a fireball 1,864 miles  (3,000 km) in space.  

 

As the remaining twenty fragments slammed into Jupiter over the next seven days, scientists were thrilled, but horrified, to witness the devastation associated with a comet impact.  Fragment G created an explosion, which was over 50,000° Fahrenheit (27,760° C), and left a mark 7,456 miles (12,000 km) on Jupiter. That's roughly the diameter of Earth.

 

Shoemaker-Levy 9 was the first time scientists were able to witness two massive celestial bodies collide in our own solar system and it was in our own celestial "backyard".   It was thrilling for the scientists, but sobering.  What if Shoemaker-Levy 9 had hit Earth instead of Jupiter?

 

The destruction caused by Shoemaker-Levy 9 inspired a slew of mediocre disaster movies like Deep Impact and Armageddon.  More importantly, it caused astrophysicists to wonder if, like a protective older brother, Jupiter has been fighting battles for its smaller sibling Earth for billions of years.  Was Jupiter ending the existence of some comets that could have otherwise hit Earth and claimed countless lives?

 

These celestial beat-downs might occur more frequently than ever imagined. 

 

In 2009, fifteen years after Shoemaker-Levy 9 exploded in Jupiter’s atmosphere, a dark spot the size of the Pacific Ocean was detected on Jupiter.  The suspect was an unobserved asteroid impact.  On June 3, 2010, something hit Jupiter again prompting Don Yeomans, head of NASA's Near Earth Object program at JPL, to say, “Jupiter is getting hit more than we expected… Back in the days of Shoemaker-Levy 9, we thought that we should see an impact on Jupiter once every hundred years or so….but look where we are now…two impacts within the past twelve months alone.  It's time to revise our impact models.”

 

Comet Siding Spring will come very close to Mars on October 19, 2014. If it did hit Mars, Siding Spring would have been the second comet observed hitting a planet within two decades.

 

 

Orbital Period of Comet Shoemaker-Levy 9

Comet Shoemaker-Levy 9, like other comets, was formed when the solar system was in its infancy.  It existed for billions of years until it finally collided with Jupiter in 1994.  The orbital period of Shoemaker-Levy 9, prior to being captured by the gravitational pull Jupiter somewhere between 1929 and 1972 is unknown.