September 26th is the next full moon. That night, I recommend getting hold of a pair of field glasses and having a look at our closest significant stellar neighbour. In particular, note the large impact crater near the moon’s south pole. The Tycho Brahe crater was determined to be about 100 million years old, on the basis of samples collected by the Apollo 17 mission. While such craters soon fall victim to erosion from air and water on Earth, they are well preserved on the airless moon.
Such craters are not just of geological interest. They testify to the reality of impacts from comets and asteroids. A sufficiently large such strike could have devastating effects for humanity. In 2029, we will get a reminder of how close some objects are to hitting us, when the 99942 Apophis asteroid will pass so close to the Earth that it will be between communications satellites in geostationary orbits and us. For a while, this asteroid topped the Torino impact hazard scale. NASA estimates that the impact of Apophis would be equivalent to the explosion of 880 megatonnes of TNT: about 58,000 times the yield of the atomic bomb dropped on Hiroshima.
There is a small but real chance that the close pass of Apophis will alter its course such that it hits us on its next pass, in 2036. In response, a spaceflight subsidiary of EADS called Astrium is proposing a mission to learn more about the asteroid, study its composition, and investigate options for deflecting its orbit, if necessary.
In one sense, we are lucky with Apophis. It was discovered back in 2004 and has since had its orbit accurately tracked. A comet, by contrast, is essentially invisible until proximity to the sun causes it to melt and produce a tail. It is entirely possible that such an object could strike the Earth with little or no warning whatsoever.
More:
Asteroid deflection strategies
The American Association for the Advancement of Science
Making an impact
Feb 22nd 2007 | SAN FRANCISCO
From The Economist print edition
The first of five reports from America’s annual gathering of scientists looks at the threat of being hit by an asteroid
Gene Shoemaker
Jul 31st 1997
From The Economist print edition
Eugene Shoemaker, master of cosmic collisions, died on July 18th, aged 69
Paleoforensic science
The asteroid did it
Nov 19th 1998
From The Economist print edition
Near-earth objects
Far away, so close
Sep 30th 2004
From The Economist print edition
A large asteroid sweeps by Earth. Where are the others?
Comets
Star-spangled slammer
Jun 30th 2005
From The Economist print edition
Deep Impact prepares to live up to its name
This may interest you:
Diluting the scientific method: Ars looks at homeopathy
By John Timmer, Chris Lee, Jonathan M. Gitlin, Matt Ford | Published: September 11, 2007 – 10:57PM CT
I forgot to mention one of the most amusing ways to learn about orbits:
Playing Spaced Penguin
You get to use a Giant Penguin Slingshot, after all.
When it comes to observing lunar crates, it may be better to wait until a half moon or similar, when the terminator is near the desired crater. Then, shadows will offer an idea as to how high the craters are. During a full moon, it’s all very bland.
Random bloke,
Thanks for the suggestion.
The full moon of September is the occasion of O-Tsukimi, Japanese moon viewing parties. While you’re gazing at the full moon have some sake and mooncakes (aka mochi) and write a haiku in honor of Near-Earth Objects.
Jessica,
That sounds like good fun.
Scores ill in Peru ‘meteor crash’
Hundreds of people in Peru have needed treatment after an object from space – said to be a meteorite – plummeted to Earth in a remote area, officials say.
They say the object left a deep crater after crashing down over the weekend near the town of Carancas in the Andes.
The Dawn Mission, launched on September 27, 2007, is NASA’s mission to send a robotic space probe to the two most massive members of the asteroid belt: the asteroid Vesta and the dwarf planet Ceres. Dawn is scheduled to explore Vesta between 2012 and 2013, and Ceres in 2015.
“Like climate monitoring, guarding the planet from asteroids always seems to fall between the cracks. Neither NASA nor the European Space Agency (ESA) has a mandate to stave off human extinction. The closest they come is NASA’s Spaceguard Survey, a $4-million-a-year telescope observing program to scan near-Earth space for kilometer-size bodies, the range that can cause global as opposed to merely regional destruction. But no one has done a systematic search for region destroyers, an estimated 20,000 of which come within striking range of our planet. No Office of Big Space Rocks is standing by to evaluate threats and pick up the red phone if need be. It would take 15 years or longer to mount a defense against an incoming body, assuming that the technology were ready to go, which it isn’t.
“Right now the U.S. doesn’t h
“All civilizations become either spacefaring or extinct.”
Carl Sagan
Sandia supercomputers offer new explanation of Tunguska disaster
Smaller asteroids may pose greater danger than previously believed
ALBUQUERQUE, N.M. — The stunning amount of forest devastation at Tunguska a century ago in Siberia may have been caused by an asteroid only a fraction as large as previously published estimates, Sandia National Laboratories supercomputer simulations suggest.
“The asteroid that caused the extensive damage was much smaller than we had thought,” says Sandia principal investigator Mark Boslough of the impact that occurred June 30, 1908. “That such a small object can do this kind of destruction suggests that smaller asteroids are something to consider. Their smaller size indicates such collisions are not as improbable as we had believed.”
There’s more to this than just an impact event. The works of Clube and Napier bring out the issues of massive imputs of comet dust and debris. These can cause as much or more problems than a massive impact. You might find this article which references their work quite interesting:
http://www.sott.net/articles/show/129699-The-Hope
A Canadian gadget that may save the world
In two years, a suitcase-sized telescope will boldly soar into space on a mission to detect crashing asteroids before it’s too late
DAWN WALTON
From Friday’s Globe and Mail
June 27, 2008 at 4:38 AM EDT
PRIDDIS, ALTA. — The space telescope will be no bigger than a hefty suitcase and weigh just 65 kilograms, but the Canadian scientists behind the project say when the device is launched two years from now, it may well go on to save the world.
The $12-million Near Earth Object Surveillance Satellite, dubbed NEOSSat, is considered a world’s first – designed specifically as an early warning system to pinpoint asteroids on a collision course with Earth. It will also detect space junk in the path of other orbiting satellites to prevent crashes that could shut down telecommunications – television, telephone, GPS and banking systems – around the globe.
“The world’s largest digital camera is to be used to keep an eye out for asteroids heading towards Earth. The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) has been built by researchers at MIT’s Lincoln Lab. At its heart is a 1.4 billion pixel (or 1400 megapixel) camera that will scan the night sky looking for rogue near-Earth objects from atop Mount Haleakala in Maui Island, Hawaii. The system uses something called an orthogonal transfer CCD to remove atmospheric blur from images.”
Algae First To Recover After Asteroid Strike
“The asteroid that impacted earth 65 million years ago killed off dinosaurs, but microalgae bounced back from the global extinction in about 100 years or less. Julio Sepúlveda, a geochemist at MIT, studied the molecular remains of microorganisms by extracting organic residues from rocks dated to the K-T extinction (in this research referred to as Cretaceous-Paleogene), and his results show that the ocean algae community greatly shrunk in size but only for about a century. ‘We found that primary production in this part of the ocean recovered extremely rapidly after the impact,’ says Julio Sepúlveda. Algae leave certain signatures of organic compounds and isotopes of carbon and nitrogen; bacteria leave different signatures. In the earliest layers after the asteroid impact, the researchers found much evidence for bacteria but little for algae, suggesting that right after the impact, algae production was greatly reduced. But the chemical signs of algae start to increase immediately above this layer. A full recovery of the ocean ecosystem probably took about a million years, but the quick rebound of photosynthesizing algae seems to confirm models that suggest the impact delivered a swift, abrupt blow to the Earth’s environment.”
“The picture that is emerging, then, is of a strange set of coincidences. First, two of the biggest impacts in history happened within 300,000 years of each other—a geological eyeblink. Second, they coincided with one of the largest periods of vulcanicity in the past billion years. Third, one of them just happened to strike where these volcanoes were active. Or, to put it another way, what really killed the dinosaurs was a string of the most atrocious bad luck.“
Dealing with asteroid strikes
A close shave
After a hit and a near miss minds are focusing on the risks from space rocks