This image shows a large impact on Jupiter's south polar region captured on July 20, 2009, by NASA's Infrared Telescope Facility in Mauna Kea, Hawaii. Image credit: NASA/JPL/Infrared Telescope Facility.
Scientists have found evidence that another object has bombarded Jupiter, exactly 15 years after the first impacts by the comet Shoemaker-Levy 9.
"It could be the impact of a comet, but we don't know for sure yet," said Glenn Orton, a scientist at JPL. -- FOX News
Just great. Something the size of Earth just hit Jupiter. No one knows what it was. No one saw it coming.
Why is no one asking how safe the Earth is from such a hazard?
In an April 2009 report, the 1st IAA Planetary Defense Conference stated:
By far the most important requirement of a successful [Earth strike] mitigation campaign is a warning time sufficient to carry out the mitigation mission. As a result, the most important aspect of mitigation is finding the hazardous objects many years in advance.
We can take some comfort from the knowledge that NASA's Near Earth Object (NEO) Program tracks known objects for possibilities of future impact with Earth over the next 100 years.
But what about unknown objects?
The good news is that there are no fewer than ten NEO discovery teams either in full operation or in the planning stages and NASA's search program designed to discover 90% of the NEO population (1 km in diameter or larger) within 10 years is under way.
The blue area shows all near-Earth asteroids while the red area shows only large near-Earth asteroids (those with diameters roughly one kilometer and larger).
Currently, the best estimate of the total population of NEOs larger than one kilometer is about 1000.
When the discovery of a new NEO is announced by the Minor Planet Center (MPC), NASA's Sentry tracking system springs into action, automatically (usually within an hour or two) computing the impact risk.
So, given today's excellent tracking capabilities how dangerous are NEOs?
What has kept the Earth "safe" at least the past 65 million years, other than blind luck is the massive gravitational field of Jupiter, our cosmic guardian, with its stable circular orbit far from the sun, which assures a low number of impacts resulting in mass extinctions by sweeping up and scattering away most of the dangerous Earth-orbit-crossing comets and asteroids.
Still, the risk of missing the one is great. How great? Dr. Stephen Hawking believes that asteroid impacts are the biggest threat to intelligent life in the galaxy.
As of July 21, 2009, Sentry was tracking 247 Near Earth Asteroids, 4 of which were just discovered in June and July.
1 comments:
Wow, I didn't even hear about this. I read a fascinating article about near earth objects last year and the focus of NASA via the White House. The article discussed the impact sites from meteors falling to the earth and how they have been categorized all over the earth. Because of this, they know that being hit by an asteriod/meteor is likely to happen every X amount of years. That said, because more than half of the planet is covered in water, this more than doubles the likelihood of the earth being hit. With Jupiter recently being pummeled with some large object that wasn't even on anyone's radar, that's a bit of a concern. Though you bring up near earth objects to the white house and they want to build a colony on teh moon or go to Mars and to heck with funding for the NEO program. You can definitely rely on the White House for making decisions that is in the human race's best interest. Great blog, by the way!
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