Ben Langford
Northern Territory News
Thu, 01 May 2008 13:59 EDT
FIVE mine workers are convinced they saw a UFO fly over them on a remote Territory island.
Mine maintenance worker Arnold Murray said a bright object whizzed over the Gemco mine site on Groote Eylandt as he and his colleagues started the night shift last Friday.
Mr Murray, 32, said the bright light was slightly higher than a plane coming to land -- but it was silent.
He and four workmates were at the mine site at 7.15pm when he saw an object flying towards them.
''I noticed a star in the sky and it was getting closer,'' he said.
''As it approached I realised it was at plane level.
''Four other lads walked out of the office and we watched it for a little while. It was vertical from us, there were no flashing lights or noise.
''The plant's pretty quiet at night. (It made) no noise whatsoever.
''All of a sudden it shot off and left a long orange trail behind it. That orange trail just faded out like a shooting star.''
Mr Murray said they wanted to know what flew over their heads in the night: ''It wasn't a chopper, it wasn't a plane, we knew that much, and it definitely wasn't a shooting star.''
''It blew us out of the water.''
Defence spokeswoman Kelly Cooper said the object was not a military plane: ''There were no military aircraft flying in that area at that time on that day,'' she said.
She said any navy ships letting off flares would have been at least 200 nautical miles off shore.
Groote Eylandt, in the Gulf of Carpentaria, is near one of the first and most famous UFO sightings in Australia -- the ''light wheel'' reported on January 23, 1964.
Sailors on a vessel off the northeast point of the island reported
seeing a circle of pulsing lights rotating clockwise, and they said
their compass went ''haywire''.
'Sonic boom' preceded 5.2 quake near Burnt Ranch, Northern California
Carol Harrison
The Eureka Reporter
Thu, 01 May 2008 14:10 EDT
A magnitude-5.2 earthquake, centered 11 miles east southeast of Willow Creek, jolted the North Coast at 8:03 p.m. on Tuesday.
The Unites States Geological Survey termed it a level VI temblor with a strong shake and light damage.
A magnitude-2.0 aftershock hit five minutes later, 16 miles to the east of Willow Creek.
"It was sort of like a sonic boom," said Brenda Simmons of SkyCrest Lake resort in Burnt Ranch. "It was a very loud noise before the house started shaking. It was pretty scary, the biggest thing I've ever felt here. (It) lasted 10 seconds max. I didn't feel the aftershock."
"We felt it good," said Terri Castner of Willow Creek. "It was a short one with a heavy shake. We've got a free-floating ceiling fan and it was rocking and rolling."
Castner's cat raced off her lap at the first vibration; a gentleman shopping in the Willow Creek Ray's Food Place sprinted for the door.
"Everyone had time to go outside and come back and the glass shelf was still shaking," longtime Ray's cashier Ginger Reeves said. "It was a hard jolt, but things kept swaying for a couple minutes afterwards. We had a few things fall off the shelf. Nothing major. It wasn't as bad as the big one in Ferndale a few years ago. That knocked me off my feet."
"I thought it was me at first," Janel Trunkey at Willow Creek Pizza Factory said. "I thought it was pretty heavy. We only had one person in here at the time. He was shocked."
Trunkey said a few things fell of the wall. Simmons said she lost telephone service for 10 minutes, but her rattling dishes came through undamaged.
Simmons said one concerned caller from the Forest Service put her at the center of the quake.
"I've felt earthquakes before, but never heard that loud of a noise before," she said. "My father-in-law thought it was quite exciting. I thought it was a little scary myself."
Science Daily
Fri, 02 May 2008 13:03 EDT
The sun's movement through the Milky Way regularly sends comets hurtling into the inner solar system -- coinciding with mass life extinctions on earth, a new study claims. The study suggests a link between comet bombardment and the movement through the galaxy.
 |
| ©Artby Don Davis / Courtesy of NASA |
| A large body of scientific evidence now exists that support the hypothesis that a major asteroid or comet impact occurred in the Caribbean region at the boundary of the Cretaceous and Tertiary periods in Earth's geologic history. Such an impact is suspected to be responsible for the mass extinction of many floral and faunal species, including the large dinosaurs, that marked the end of the Cretaceous period. |
Scientists at the Cardiff Centre for Astrobiology built a computer model of our solar system's movement and found that it "bounces" up and down through the plane of the galaxy. As we pass through the densest part of the plane, gravitational forces from the surrounding giant gas and dust clouds dislodge comets from their paths. The comets plunge into the solar system, some of them colliding with the earth.
The Cardiff team found that we pass through the galactic plane every 35 to 40 million years, increasing the chances of a comet collision tenfold. Evidence from craters on Earth also suggests we suffer more collisions approximately 36 million years. Professor William Napier, of the Cardiff Centre for Astrobiology, said: "It's a beautiful match between what we see on the ground and what is expected from the galactic record."
The periods of comet bombardment also coincide with mass extinctions, such as that of the dinosaurs 65 million years ago. Our present position in the galaxy suggests we are now very close to another such period.
While the "bounce" effect may have been bad news for dinosaurs, it may also have helped life to spread. The scientists suggest the impact may have thrown debris containing micro-organisms out into space and across the universe.
Centre director Professor Chandra Wickramasinghe said: "This is a seminal paper which places the comet-life interaction on a firm basis, and shows a mechanism by which life can be dispersed on a galactic scale."
The paper, by Professor Napier and Dr Janaki Wickramasinghe, is to be published in the Monthly Notices of the Royal Astronomical Society.
Adapted from materials provided by Cardiff University, via EurekAlert!, a service of AAAS.
My Dark Sky
Fri, 02 May 2008 16:33 EDT
A meteoroid is a solid object - usually are dust particles or debris from comets - that floats around in space.
When meteoroid enters and burns in the Earth's atmosphere, the visible streak in the sky is known as a meteor.
A meteorite is the meteoroid that survives and reaches Earth's surface.
An increase in the number of meteors at a particular time is called a meteor shower.
If we trace back the path of the meteors during a meteor shower, we will find that all the meteors seem to originate from a point in the sky. This point is known as the radiant.
Zenith Hourly Rate (ZHR) of a meteor shower is the number of meteor an observer would see in an hour under a dark sky with limiting magnitude of 6.5 and if the radiant was in the zenith. In reality the rate which can effectively be seen is always lower as the radiant is closer to the horizon and it also depends on the local weather condition.
~~~~~~~~~~
Meteors appear as fast-moving streaks of light in the night sky that usually will only last about a second or two. They are commonly referred to as "falling stars" or "shooting stars". Sometimes meteor may even leave a trail behind.
The vast outer space is actually not empty as it seems to be; there are a lot of dust particles, tiny grains of sand and ice floating around in space. When these particles or meteoroids come too close to Earth, Earth's gravity will pull them into the atmosphere, at a speed of 10 to 70 kilometres per second, to produce streaks of light in the night sky known as meteors.
Most meteors will completely burn up in the atmosphere at an altitude of 100 kilometres. However, some bigger chunk of meteoroids may survive the trip through the atmosphere and reach the ground. These remnants are known as meteorites.
What is Meteor Shower?
On a normal night we can typically see a few meteors per hour. This type of meteors is called the sporadic meteors. However, at certain times of the year the rate of observable meteors is much higher. These periods are called meteor showers.
Most meteor showers have their origins with comets. Comets are primarily composed of ice and dust and when they approach the Earth, the Sun's heat will evaporate the ice and they will shed an icy, dusty debris stream which is then distributed along their orbits. When our Earth passes through a comet's orbit, these left-over comet debris will "bombards" Earth and causes the rate of meteors increases.
Due to Earth orbit around the Sun, we will roughly be at the same location in space every year. Hence meteor showers will occur almost the same time each year when Earth crosses the comet's orbit. The different between the yearly showers is related to how close the comet's orbit to ours and how long ago the debris was ejected.
Why is Meteor Shower named after Constellation?
During a meteor shower, if we observe carefully, we will find that the path of the meteors seem to radiate from a point in the sky. This point is called the radiant of the meteor shower and is just a perspective effect. Actually all the meteors enter the Earth's atmosphere in a parallel path, but from our Earth perspective, the meteors appear to come from the radiant.
Meteor shower is named based on the location of their radiant. For example, if the radiant is located in constellation Perseus, the particular meteor shower is known as the Perseids. If there is more than one meteor shower in a constellation, then the shower is named after the bright star nearest to the radiant. For example, the Eta Aquarids and Delta Aquarids meteor shower are both from the constellation Aquarius.
How to observe Meteor Shower?
All you need to enjoy a meteor shower is just your naked eyes. No equipment is needed!
* Find a dark, safe and unobstructed observing site.
* Bring along star chart, red-light torchlight, food & drinks, jacket, ground-mat or sleeping bag.
* When you reach the observing site, find a place that is not easily disturbed by others.
* Check your direction and use the star chart to find the location of the radiant in the sky.
* Find a comfortable position to sit or lie down while waiting for
the meteor to appear. The best position is to lie down flat on the
ground so that you will cover the maximum area of the sky.
Why there are more Meteors after Midnight?
When Earth orbit around the Sun, basically meteoroids enter the Earth's atmosphere from all direction. The velocity of Earth around the Sun is about 30 km/s and the meteoroids' velocity is averagely 40 km/s.
Refer to the diagram, before midnight, the meteors are catching up with Earth from the back, hence the velocity of the meteor will be the different between the Earth's orbital velocity and the meteoroids' velocity, which is roughly 10 km/s.
 |
| ©Unknown |
| Meteor before & after midnight |
After midnight, the meteors are heading straight to Earth, so the velocity now is the total of both the Earth and meteoroids' velocity, which is equal to 70 km/s.
Hence, before midnight, only those meteoroids moving faster than Earth will catch up, so the amount of meteor seen is lesser. Also, the velocity of the meteor is lower before midnight, so the meteor will be dimmer during this time.
~~~~~~~~~~
Click here for handout on Meteor Shower in both English and Chinese. You are welcome to use it as teaching or handout material to the public.
Asteroids - How real is the threat?
Sskankdragon
Skankdragon's blog
Tue, 29 Apr 2008 17:24 EDT
The Doomed and the Blind
As politicians sit squabbling in Washington, deliberating and deciding, an asteroid 4 kilometers across is thundering through space at 15 miles per second. It was forged in a galactic maelstrom millions of years ago from molten metal, and now it tumbles through space with malevolent indifference. People sit unaware of an impending disaster, carrying on their daily activities while extinction encroaches. It won't just be the extinction of a few species, or a few million people, but all life will be wiped off the face of the earth within hours. Our planet will become a barren waste for millions of years, void of vibrant life and wonder.
 |
| Itokawa asteroid |
Is an awful scenario like this really plausible? The answer is yes. The threat is very real and the evidence is in the scars our earth bears on the surface, the massive craters on the moon, and the giant wounds on Mars. You would expect that something so catastrophic and horrible for our species and planet would demand attention from lawmakers; wrong. Although our government is well-informed by agencies like NASA, it has neglected to properly fund Near Earth Object (NEO) programs, and it could lead to our destruction. An asteroid impact is a natural disaster we can actually prevent, and if our representatives don't take steps to improve our warning systems, we will suffer the same fate as the dinosaurs.
As Congress approves billions of dollars for the war in Iraq, they reject a program which would well-equip us to deal with the NEO threat. The cost of the program runs from $300 million to $1.1 billion (Shoemaker), less than the cost of one B-2 stealth bomber at $1.157 billion (Scott). The lower cost would cover using or modifying existing space telescopes to look for potentially hazardous asteroids. It would cost $1.1 billion to build a new space telescope for the same purpose. Congress has rejected both of these plans because they are "too costly (Shoemaker)." Using existing systems, we have detected thousands of NEOs in our solar system. They range in size from a few hundred meters to several kilometers, the largest being the celestial body Ganymed, which is over 32 km, or 20 miles, in diameter (Near Earth Object Fact Sheet). Although it is highly unlikely, if the asteroid Ganymed hit our planet it would obliterate all life, shred the earth's crust, and bury itself deep in the mantle. It would cause massive volcanic eruptions, earthquakes, and even has a chance of ripping our planet apart.
There are over 20,000 objects with diameters greater than 140 meters, or 460 feet, that could collide with the earth. NASA scientists believe they could locate 90% of the objects by the year 2020, but funding has prevented them from doing their job (Near Earth Objects). A perfect example would be the near-miss of the asteroid 2002 EM7, which missed our planet by 298,400 miles, which is about 1.2 times the distance from earth to the moon (Britt). The object was between 40 and 80 meters across, or 130 to 260 feet, and could have destroyed an entire city if it had impacted earth. Some people think that our current system is sufficient, but here's the kicker; scientists didn't find the object days after it had passed by our planet. How can the current system be adequate when it didn't detect an object that could have slammed into our planet and killed millions of people?
The asteroid came at earth from a blind spot in which it couldn't have been detected using current systems (Britt). The solution to correcting this blind spot would be to construct an observatory or to launch a space-based platform that can observe asteroids from a different galactic vantage point. Scientists at NASA have suggested that placing an observatory around the planet Mercury could help detect objects in this blind spot, but the funding has certainly not been made available by Washington (Britt).
On November 1st, 2007 an object 50 meters across passed within 5 million miles of earth and wasn't detected until November 20th. An article on NASA's NEO website highlighted the event,
"Designated 2007 WD5, the asteroid was discovered on Nov. 20, 2007 by the NASA-funded Catalina Sky Survey using a 1.5m telescope on Mt. Lemmon, near Tucson. The object had already passed within 7.5 million km (5 million miles) of the Earth on Nov. 1, before it was discovered. (Chesley)."
Right now, this is a common occurrence. The lack of funding by Congress leaves us opens to an impact which could change the course of human history, or completely wipe us out as a species. Without a comprehensive program to detect objects of all sizes and trajectories, we leave ourselves open to a knockout blow.
An article on Space.com explains that, "about 1,000 asteroids larger than 1 kilometer (0.6 miles) are thought to lurk in orbits that might one day threaten Earth," and that "about 500 of them have been found (Britt)." The larger objects are easier to track and locate, but pose a greater threat to civilization. Smaller objects are harder to track, but could still cause localized devastation. Over Siberia in 1908, an unknown object exploded, likely an air-burst meteor, and flattened over 800 miles of trees and vegetation. The size of the object which exploded is unknown, but measurements and estimates place the size around 60 to 80 meters across (Research Center). The object caused widespread devastation, and if it had exploded over a major city it would have caused hundreds of thousands, if not millions of deaths. Objects this small are much more difficult to detect than larger objects, even today.
The size of the object is not the only thing that determines the magnitude of impact; density is also a factor. A smaller asteroid, like the 20 meter wide asteroid that left a 600 foot deep crater in Arizona, can cause as much damage as a larger asteroid with a lower density (Britt). The diameter doesn't necessarily tell the whole story. Objects larger than 500 meters across can cause widespread surface damage to the earth wherever they impact, create tsunamis, block out the sun, incinerate large areas, and kill millions of people. The larger the object, the greater the threat they pose.
As of now, the greater risk comes from the smaller asteroids which are harder to detect with our current systems. Until we develop a full catalogue of the larger asteroids, and we've detected and tracked every one, we are susceptible to a catastrophic impact, no matter how small the chance. The problem isn't warding off asteroids, because we have adequate weapons like nuclear ballistic missiles that can change an asteroid's course, but it is detecting them. Right now we aren't allocating enough resources to provide NEO researchers the tools to evaluate all potential threats.
To solve the problem of under funding by congress, I propose an ambitious presentation. Recently, the University of Arizona published a web page which allows users to 'test' their own asteroid impact. You can input projectile diameter, velocity, type of material, density, impact angle, and rock target type and you will receive a series of outputs which predict an asteroid impact (Marcus). My proposal involves a much more graphical approach, as opposed to a strictly numerical approach, but would incorporate the use of genuine data like the University of Arizona's website.
I think that the members of congress need to see visual representations of what an impact would mean for the earth. They need to see 3d models of an asteroid slamming into an American city. They need to understand how real the threat of an impact is. Rather than just a bunch of numbers and statistics, they need to see that cities will be obliterated, people will die, and the world will be changed forever by a significant or well-placed impact. I would provide graphs of damage costs, death tolls, and would show what various impacts would do to cities, shorelines, climate, and the stability of life on earth. I think that too often politicians look at problems based on numbers, and fail to see the reality of some situations.
The project will graphically explain what different size asteroids would do to urban areas, suburban areas, and rural areas. The presentation would mainly use smaller asteroids from 30 to 500 meters across as examples. It is simply more realistic and I wouldn't want to go overboard and lose credibility by proclaiming a giant asteroid, which we wouldn't be able to detect, would unknowingly slam into our world unexpectedly. Realism and graphical representation are key to convincing lawmakers to fund NEO programs. Data from actual past-earth impacts would be plugged-in to the simulation, and the result would be an accurate depiction of what might happen. I would also utilize photos of impact craters in Arizona, the Yucatan in Mexico, Siberia, and Asia, as well as craters on the moon and Mars, to quantify the threat. I think that after seeing the consequences of an impact on American cities, and seeing the evidence of past impacts, it would be incredibly hard to look away.
Over the course of human history, our species has faced many threats. Some came from predators in the wild, some from other humans, and some from space. Our ancestors were powerless to stop an incoming asteroid from striking the planet. If a 'World-Killer' asteroid had slammed into the planet, they wouldn't see it coming, and couldn't do anything about it. Now, for the first time in our history, we have the ability to prevent our own demise. We can detect and deflect incoming objects, saving millions of lives, and possibly our planet. Out there in the blackness of space, an asteroid large enough to cram the city of Phoenix hundreds of feet into the earth's mantle slowly tumbles over itself. It's in one of our blind spots, where we can't detect it. If we invest a few billion dollars in NEO programs, we can greatly reduce the possibility of being hit by surprise.
The question is: Why aren't we? The graveness of the situation needs to be appreciated by our lawmakers, as well as the public. No longer can we sit by and fund wars oblivious to the real and immense threat posed by asteroids. Write your politicians, protest in Washington, do whatever it takes for them to listen. We might not have as much time as you think, and don't let politicians tell you otherwise. They're quick to fund wars, yet quick to ignore what really matters.
Tom Spears
The Ottawa Citizen
Thu, 01 May 2008 12:00 EDT
Canada is preparing to launch the first space mission ever to search for asteroids between Earth and the sun - the type of asteroid most likely to slam into our planet.
Fittingly for this country, the Near Earth Object Surveillance Satellite is not a Hubble-sized monster. It's a 60-kilogram microsatellite, costing a mere $10 million (including the pricetag for launch) yet able to deliver science results never seen before.
NEOSSat will search for asteroids that are closer to the sun than Earth. These are nearly impossible to see from our planet's surface - there's too much atmosphere and sunshine - but easier to spot from space.
The suitcase-sized satellite is expected to launch in two years.
"This is the first space-based asteroid-searching telescope, period
... Why shouldn't Canada be the leader in a field? And it happens in
this case, we are," says Alan Hildebrand of the University of Calgary,
one of two principal scientists for the satellite.
Canada's specialty is in shrinking the equipment that holds a satellite stable in space, which allows a very small satellite to aim a telescope without having its aim wobble. "It happens that we're the world leaders in this technology," he added. Instead of launching an 11-tonne Hubble, Canada can send up a 60-kilogram "microsatellite."
Astronomers have been watching asteroids for many years. Most are located in a belt on the far side of Mars, but others are scattered here and there through the solar system. Most of the ones we know are outside Earth's orbit.
"Most people are interested in the possibility that an asteroid may impact the Earth," he said.
"What you can do from the space that you can't do from Earth is, if
you have a baffle (to block sunlight), you can look close to the sun."
Asteroids from far out in the solar system sometimes swing past Earth, but they don't stay long. The ones between us and the sun hang around our neighbourhood permanently. And the most dangerous of these have an orbit that crosses ours at times.
As well, some of these asteroids match Earth's own speed fairly closely, making it relatively easy to fly to one and land there.
"I think the most exciting thing about this mission is we are going to find asteroids that are accessible from our planet," Mr. Hildebrand said. "So I see it as leveraging other exploration, both manned and unmanned," to land on asteroids.
"We've been to the moon. There's always more you can do (there), but asteroids have so much more to teach us about the origins of the solar system."
Many asteroids are leftovers from the original material of the solar system, unlike the moon, which has evolved over time. And some have water and other materials of interest. As well, their weak gravity makes it easier to land, and escape again, than the moon and Mars allow.
No one has ever done a systematic survey for asteroids inside Earth's orbit. Estimates say there could be about 50 big ones (more than a kilometre wide), and perhaps thousands of little ones.
In a second mission, NEOSSat will also track the paths of other satellites in very high orbits. NEOSSat is based on the design of MOST, a hugely successful - and very small - Canadian satellite launched in 2003 that's looking at stars right now. MOST and NEOSSat are both flying telescopes, mini-versions of the 11-tonne Hubble.
The new satellite will look on an angle about 45 degrees away from the sun, looking for objects that move from one photo to the next.
The mission a partnership of agencies led by the Canadian Space Agency and Defence Research and Development Canada. Brad Wallace is the lead scientist at Defence R&D Canada. The prime contractor is Dynacon Inc.
"It's a new paradigm for doing science from space. You don't have to
put up hundreds of millions ... or billions of dollars' worth of
hardware," says astronomer Peter Brown of the University of Western
Ontario, a member of the science team for the new satellite. "You can
start doing things in smaller packages with smaller electronics."
Canada space mission targets asteroids
Tom Spears
Canwest News Service
Fri, 02 May 2008 23:55 EDT
Canada is preparing to launch the first space mission ever to search for asteroids between Earth and the sun -- the type of asteroid most likely to slam into our planet.
 |
| ©Unknown |
Fittingly for this country, the Near Earth Object Surveillance Satellite is not a Hubble-sized monster. It's a 60-kilogram microsatellite, costing a mere $10 million, yet able to deliver science results never seen before.
NEOSSat will search for asteroids that are closer to the sun than Earth. These are nearly impossible to see from our planet's surface -- there's too much atmosphere and sunshine -- but easier to spot from space.
The suitcase-sized satellite is expected to launch in two years.
"This is the first space-based asteroid-searching telescope, period . . . Why shouldn't Canada be the leader in a field? And it happens in this case, we are," says Alan Hildebrand of the University of Calgary, one of two principal scientists for the satellite.
Canada's specialty is in shrinking the equipment that holds a satellite stable in space, which allows a very small satellite to aim a telescope without having its aim wobble.
"It happens that we're the world leaders in this technology," he added.
Instead of launching an 11-tonne Hubble, Canada can send up a 60-kilogram "microsatellite."
Astronomers have been watching asteroids for many years. Most are located in a belt on the far side of Mars, but others are scattered here and there through the solar system. Most of the ones we know are outside Earth's orbit.
"Most people are interested in the possibility that an asteroid may impact the Earth," Hildebrand said.
"What you can do from the space that you can't do from Earth is, if you have a baffle (to block sunlight), you can look close to the sun."
Asteroids from far out in the solar system sometimes swing past Earth, but they don't stay long. The ones between us and the sun hang around our neighbourhood permanently. And the most dangerous of these have an orbit that crosses ours at times.
As well, some of these asteroids match Earth's own speed fairly closely, making it relatively easy to fly to one and land there.
"I think the most exciting thing about this mission is we are going to find asteroids that are accessible from our planet," Hildebrand said.
"So I see it as leveraging other exploration, both manned and unmanned," to land on asteroids.
"We've been to the moon. There's always more you can do (there), but asteroids have so much more to teach us about the origins of the solar system."
Many asteroids are leftovers from the original material of the solar system, unlike the moon, which has evolved over time. And some have water and other materials of interest. As well, their weak gravity makes it easier to land, and escape again, than the moon and Mars allow.
No one has ever done a systematic survey for asteroids inside Earth's orbit. Estimates say there could be about 50 big ones -- more than a kilometre wide -- and perhaps thousands of little ones.
The mission is a partnership of agencies led by the Canadian Space Agency and Defence Research and Development Canada.
The eta Aquarid meteor shower peaks
Space Weather
Sun, 04 May 2008 18:48 EDT
The eta Aquarid meteor shower peaks this year on Monday, May 5th, and Tuesday, May 6th. The best time to look, no matter where you live, is during the hours immediately before sunrise. If you can, get away from city lights; you will see more meteors from the dark countryside.
2008 should be a good year for the eta Aquarid meteors. The Moon is new, which means no lunar glare, and Earth is expected to pass through an unusually dense region of comet dust, driving meteor rates as high as 70 per hour in the southern hemisphere. Sky watchers in Australia, New Zealand, South America and southern Africa are favored. It is possible to see the shower from the northern hemisphere, too, but rates are reduced to less than 30 per hour.
The eta Aquarids are flakes of dust from Halley's Comet, which last visited Earth in 1986. Although the comet is now far away, beyond the orbit of Uranus, it left behind a stream of dust. Earth passes through the stream twice a year in May and October. In May we have the eta Aquarid meteor shower, in October the Orionids. Both are caused by Halley's Comet.
The eta Aquarids are named after a 4th-magnitude star in the constellation Aquarius. The star has nothing to do with the meteor shower except that, coincidentally, meteors appear to emerge from a point nearby. Eta Aquarii is 156 light years from Earth and 44 times more luminous than the Sun.
The constellation Aquarius does not rise very far above the horizon in the northern hemisphere, and that's why northerners see relatively few meteors. But the ones they do see could be spectacular Earthgrazers.
Sky maps: Northern Hemisphere | Southern Hemisphere
Earthgrazers are meteors that skim horizontally through the upper atmosphere. They are slow and dramatic, streaking far across the sky. The best time to look for Earthgrazers is between 2:00 to 2:30 a.m. local time when Aquarius is just peeking above the horizon.
Experienced meteor watchers suggest the following viewing strategy: Dress warmly. Bring a reclining chair, or spread a thick blanket over a flat spot of ground. Lie down and look up somewhat toward the east. Meteors can appear in any part of the sky, although their trails will point back toward Aquarius.
Tidbits:
* Eta Aquarid meteoroids hit Earth's atmosphere traveling 66 km/s.
* Typical eta Aquarid meteors are as bright as a 3rd magnitude star.
Asteroid Impact 65 Million Years Ago Triggered A Global Hail Of Carbon Beads
ScienceDaily
Mon, 05 May 2008 20:10 EDT
 |
| ©Mark Harvey |
| Carbon cenospheres are tiny, carbon-rich particles that form when coal and heavy fuel are heated intensely. Scientists have now learned that cenospheres can form in the wake of asteroid impacts, too. |
The asteroid presumed to have wiped out the dinosaurs struck the Earth with such force that carbon deep in the Earth's crust liquefied, rocketed skyward, and formed tiny airborne beads that blanketed the planet, say scientists from the U.S., U.K., Italy, and New Zealand in this month's Geology.
The beads, known to geologists as carbon cenospheres, cannot be formed through the combustion of plant matter, contradicting a hypothesis that the cenospheres are the charred remains of an Earth on fire. If confirmed, the discovery suggests environmental circumstances accompanying the 65-million-year-old extinction event were slightly less dramatic than previously thought.
"Carbon embedded in the rocks was vaporized by the impact, eventually forming new carbon structures in the atmosphere," said Indiana University Bloomington geologist Simon Brassell, study coauthor and former adviser to the paper's lead author, Mark Harvey.
The carbon cenospheres were deposited 65 million years ago next to a thin layer of the element iridium -- an element more likely to be found in Solar System asteroids than in the Earth's crust. The iridium-laden dust is believed to be the shattered remains of the 200-km-wide asteroid's impact. Like the iridium layer, the carbon cenospheres are apparently common. They've been found in Canada, Spain, Denmark and New Zealand.
But the cenospheres' origin presented a double mystery. The cenospheres had been known to geologists only as a sign of modern times -- they form during the intense combustion of coal and crude oil. Equally baffling, there were no power plants burning coal or crude oil 65 million years ago, and natural burial processes affecting organic matter from even older ages -- such as coals from the 300-million-year-old Carboniferous Period -- had simply not been cooked long or hot enough.
"Carbon cenospheres are a classic indicator of industrial activity," Harvey said. "The first appearance of the carbon cenospheres defines the onset of the industrial revolution."
The scientists concluded the cenospheres could have been created by a new process, the violent pulverization of the Earth's carbon-rich crust.
Geologists do believe the Earth burned in spots as molten rock and super-hot ash fell out of the sky and onto flammable plant matter. But the charcoal-ized products of these fires only appear in some places on Earth, and are more often found near the asteroid impact site of Chicxulub Crater, just west of Mexico's Yucatan Peninsula. Some geologists had thought all carbon particles resulting from the impact was ash from global scale forest fires, but the present research strongly contradicts that assumption.
The scientists examined rock samples from eight marine locations in New Zealand, Italy, Denmark and Spain. They also examined carbon-rich particles from five non-marine locations in the U.S. and Canada. Following chemical and microscopic analysis, the researchers concluded the particles were carbon cenospheres, similar to the ones produced by industrial combustion.
The scientists also found that the farther the sample site was from the Chicxulub Crater, the smaller the cenospheres tended to be. That observation is consistent with the expectation that particles were produced by the asteroid impact, since once the particles are ejected, heavier particles should fall back to Earth sooner (and travel shorter distances) than lighter particles.
Last, the scientists estimated the total mass of carbon cenospheres ejected by the asteroid collision, assuming a global distribution, to be perhaps as much as 900 quadrillion kilograms. Whether or not the carbon cenospheres are truly ubiquitous, however, needs further corroboration.
"There are still clues to unravel about the events occurring around the time of the impact," Brassell said. "And there are aspects of the Earth's natural carbon cycle that we didn't previously consider."
Harvey is interested in the unique properties of the cenospheres themselves. "Perhaps we can generate and study carbon cenospheres to better understand them," he said. "We also need to look for the cenospheres in other parts of the world and also around the time of other extinction events."
Harvey conducted the research while he was a master's student at IU
Bloomington. He is now a geoscientist for Sinclair Knight Merz in New
Zealand. Claire Belcher (University of London) and Alessandro Montanari
(Coldigioco Geological Observatory) also contributed to the study. It
was funded by the Geological Society of America, the Indiana University
Department of Geological Sciences, and the Society for Organic
Petrology.
65-million-year-old asteroid impact triggered a global hail of carbon beads
Indiana University
Mon, 05 May 2008 14:25 EDT
The asteroid presumed to have wiped out the dinosaurs struck the Earth with such force that carbon deep in the Earth's crust liquefied, rocketed skyward, and formed tiny airborne beads that blanketed the planet, say scientists from the U.S., U.K., Italy, and New Zealand in this month's Geology.
The beads, known to geologists as carbon cenospheres, cannot be formed through the combustion of plant matter, contradicting a hypothesis that the cenospheres are the charred remains of an Earth on fire. If confirmed, the discovery suggests environmental circumstances accompanying the 65-million-year-old extinction event were slightly less dramatic than previously thought.
"Carbon embedded in the rocks was vaporized by the impact, eventually forming new carbon structures in the atmosphere," said Indiana University Bloomington geologist Simon Brassell, study coauthor and former adviser to the paper's lead author, Mark Harvey.
 |
| ©Mark Harvey |
| Carbon cenospheres are tiny, carbon-rich particles that form when coal and heavy fuel are heated intensely. Scientists have now learned that cenospheres can form in the wake of asteroid impacts, too. |
The carbon cenospheres were deposited 65 million years ago next to a thin layer of the element iridium -- an element more likely to be found in Solar System asteroids than in the Earth's crust. The iridium-laden dust is believed to be the shattered remains of the 200-km-wide asteroid's impact. Like the iridium layer, the carbon cenospheres are apparently common. They've been found in Canada, Spain, Denmark and New Zealand.
But the cenospheres' origin presented a double mystery. The cenospheres had been known to geologists only as a sign of modern times -- they form during the intense combustion of coal and crude oil. Equally baffling, there were no power plants burning coal or crude oil 65 million years ago, and natural burial processes affecting organic matter from even older ages -- such as coals from the 300-million-year-old Carboniferous Period -- had simply not been cooked long or hot enough.
"Carbon cenospheres are a classic indicator of industrial activity," Harvey said. "The first appearance of the carbon cenospheres defines the onset of the industrial revolution."
The scientists concluded the cenospheres could have been created by a new process, the violent pulverization of the Earth's carbon-rich crust.
Geologists do believe the Earth burned in spots as molten rock and super-hot ash fell out of the sky and onto flammable plant matter. But the charcoal-ized products of these fires only appear in some places on Earth, and are more often found near the asteroid impact site of Chicxulub Crater, just west of Mexico's Yucatan Peninsula. Some geologists had thought all carbon particles resulting from the impact was ash from global scale forest fires, but the present research strongly contradicts that assumption.
The scientists examined rock samples from eight marine locations in New Zealand, Italy, Denmark and Spain. They also examined carbon-rich particles from five non-marine locations in the U.S. and Canada. Following chemical and microscopic analysis, the researchers concluded the particles were carbon cenospheres, similar to the ones produced by industrial combustion.
The scientists also found that the farther the sample site was from the Chicxulub Crater, the smaller the cenospheres tended to be. That observation is consistent with the expectation that particles were produced by the asteroid impact, since once the particles are ejected, heavier particles should fall back to Earth sooner (and travel shorter distances) than lighter particles.
Last, the scientists estimated the total mass of carbon cenospheres ejected by the asteroid collision, assuming a global distribution, to be perhaps as much as 900 quadrillion kilograms. Whether or not the carbon cenospheres are truly ubiquitous, however, needs further corroboration.
"There are still clues to unravel about the events occurring around the time of the impact," Brassell said. "And there are aspects of the Earth's natural carbon cycle that we didn't previously consider."
Harvey is interested in the unique properties of the cenospheres
themselves. "Perhaps we can generate and study carbon cenospheres to
better understand them," he said. "We also need to look for the
cenospheres in other parts of the world and also around the time of
other extinction events."
Nasa plans landing on 40m-wide asteroid travelling at 28,000mph
Ian Sample
Guardian
Wed, 07 May 2008 15:10 EDT
· US eyes 2000SG344 for Armageddon-type mission
· Rock seen as stepping stone to deep space
It was once considered the most dangerous object in the universe, heading for Earth with the explosive power of 84 Hiroshimas. Now an asteroid called 2000SG344, a lump of rock barely the size of a large yacht, is in the spotlight again, this time as a contender for the next giant leap for mankind.
 |
| ©Science Photo Library / Guardian |
| Initial calculations showed that there was a chance that the asteroid Apophis would strike Earth at its close approach on April 13 2029. |
Nasa engineers have identified the 1.1m tonne asteroid, which in 2000 was given a significant chance of slamming into Earth, as a potential landing site for astronauts, ahead of the Bush administration's plans to venture deeper into the solar system with a crewed voyage to Mars.
The mission - the first to what officials call a Near Earth Object (NEO) - is being floated within the US space agency as a crucial stepping stone to future space exploration.
A report seen by the Guardian notes that by sending astronauts on a three-month journey to the hurtling asteroid, scientists believe they would learn more about the psychological effects of long-term missions and the risks of working in deep space, and it would allow astronauts to test kits to convert subsurface ice into drinking water, breathable oxygen and even hydrogen to top up rocket fuel. All of which would be invaluable before embarking on a two-year expedition to Mars.
Under the Bush administration, Nasa has been charged with sending astronauts back to the moon, beginning in 2020 and culminating in a permanent lunar outpost, itself a jumping off point for more distant Mars missions. With the agency's ageing fleet of space shuttles due to be retired soon after 2010, the agency has begun work on a replacement called Orion and a series of Ares rockets that will blast them into orbit.
In a study due to be published next month, engineers at Nasa's Johnson Space Centre in Houston and Ames Research Centre in California flesh out plans to use Orion for a three to six month round-trip to the asteroid, with astronauts spending a week or two on the rock's surface.
As well as giving space officials a taste of more complex missions, samples taken from the rock could help scientists understand more about the birth of the solar system and how best to defend against asteroids that veer into Earth's path.
"An asteroid will one day be on a collision course with Earth. Doesn't it make sense, after going to the moon, to start learning more about them? Our study shows it makes perfect sense to do this soon after going back to the moon," said Rob Landis, an engineer at Johnson Space Centre and co-author of the report, which is due to be published in the journal Acta Astronautica.
More precise measurements of the orbit of 2000SG344 have allayed fears that it could hit Earth sometime around the end of September 2030, but the asteroid is still expected to come close in astronomical terms.
The report lays out plans for a crew of two to rendezvous with a speeding asteroid that is due to pass close by Earth. After a seven-week outward journey, the Orion capsule would swing around and close in on the rock.
Because gravity is close to zero on asteroids, the capsule would need to attach itself, possibly by firing anchors into the surface. For the same reason, astronauts would not be able to walk around on the surface as they did on the moon. "On some of these asteroids, you could jump up and go into orbit, or maybe even leave for good," said Landis.
A round trip to an asteroid could be done with less fuel than a moon mission, but is technically very challenging. The asteroid is only 40 metres across and spins as it hurtles through space at 28,000mph.
Landis thinks that a trip to an asteroid could capture imaginations even more than a return to our nearest celestial neighbour. "When we head back to the moon, I think we'll see many of the same scenes we saw in the 60s and 70s Apollo programme. We've been to the moon, we got that T-shirt back in 1969. But whenever we've sent robotic probes to look at asteroids, we've always been surprised at what we've seen," he said.
Because asteroids were forged in the earliest days of the solar system, analysing samples from them could shed light on the conditions that prevailed when the Earth was formed.
"Near Earth objects are a potential collision hazard to Earth and it
may one day be necessary to deflect an asteroid from a collision course
with Earth," said Ian Crawford, a planetary scientist at Birkbeck
College, London. "Having the capability in your back pocket to deflect
an asteroid might be a good insurance policy for the future, and for
that, you want to know what they are made of, how to rendezvous with
them, and whether you risk getting hit by debris if you fire something
at it."
New York State: NEADS says loud noise could have been a sonic boom
wktv.com
Wed, 07 May 2008 17:13 EDT
We've had lots of phone calls into the newsroom today about a loud booming sound this afternoon. Some viewers even felt their homes shaking.
North East Air Defense Sector officials say there was plenty of air
traffic today, and the sound could have been a sonic boom. But that is
not confirmed.
Canada to launch asteroid-hunting satellite
Thetechherald.com
Thu, 08 May 2008 19:24 EDT
 |
| ©CSA |
| The CSA is to launch a suitcase-sized satellite to detect Near Earth Objects. |
A team led by the Canadian Space Agency is set to launch a microsatellite designed to detect near-Earth asteroids from space.
The 60-kilogram, $10 million, Near Earth Object Surveillance Satellite (NEOSSat) will search for asteroids between the Earth and Sun, the ones most likely to pose a danger to our planet.
More than 5000 such objects have been found with orbits that would make them a risk of collision with the Earth.
The suitcase-sized satellite will be in a unique position to spot any danger from the asteroids which are often difficult to detect from Earth-based observatories.
"This is the first space-based asteroid-searching telescope, period," said Alan Hildebrand of the University of Calgary, one of two principal scientists for the satellite to reporters.
"It happens that we're the world leaders in this technology," he added.
Hildebrand said the mission also was the basis of further asteroid research.
"I think the most exciting thing about this mission is we are going to find asteroids that are accessible from our planet," Hildebrand said."So I see it as leveraging other exploration, both manned and unmanned," to land on asteroids, reported Canada.com.
"We've been to the moon. There's always more you can do (there), but asteroids have so much more to teach us about the origins of the solar system," he said.
"NEOSSAT may indeed contribute to our knowledge of extremely interior asteroids, and in that light I look forward to what it may find," said Alan Harris of the Space Science Institute in Boulder Colorado, US to the New Scientist.
The satellite will rely on a telescope with a 15-centimetre mirror, similar to that used by amateur astronomers.
It is expected to be launched in two years time.
Comets might have caused ancient American extinctions 13,000 years ago
WebIndia123.com
Thu, 08 May 2008 05:53 EDT
Scientists have come up with a controversial theory which suggests that huge comet impacts wiped out North America's large mammals 13,000 years ago.
According to a report in National Geographic News, the hypothesis, first presented in May 2007, proposes that an onslaught of extraterrestrial bodies caused the mass extinction known as the "Younger Dryas event" and triggered a period of climatic cooling.
Around this time, large mammals including mammoths, mastodons, horses, camels, and saber-toothed cats went extinct in North America.
James Kennett, a geologist at the University of California, Santa Barbara, is one of the main proponents of the comet-impact hypothesis.
He said the theory is consistent in explaining and linking these various phenomena.
"We suggest it's a series of aerial bursts, more of a multiple Tunguska event, like a shotgun," he said, referring to the explosion of an extraterrestrial object over Siberia in 1908.
"This would also explain evidence of fires across swaths of North America," he added.
He and his colleagues have also found widespread and abundant minuscule diamonds and magnetic particles in the layer of Earth that dates to this time.
These features were formed in the extremely hot and high-pressure environment created by the series of explosions, Kennett suggested.
"It's obviously an outrageous hypothesis; in the sense that it wasn't predicted. It has come out of left field," said Kennett. "But all I can say is that I don't know of any other process that can account for the wide display of data that we have and continue to generate other than some kind of an extraterrestrial impact," he added.
But the theory has been debated widely since it was introduced.
Stuart Fiedel from the Louis Berger Group, a private archaeological firm in Richmond, Virginia, argued that the theory fails to address some major questions-like how comet blasts could have wiped out woolly mammoths and saber-toothed cats in North America, while leaving humans unscathed.
"If this impact was powerful enough to fricassee mammoths and mastodons and short-faced bears and other big fauna that were on the landscape, you would think that it would have decimated the human population as well-not only by direct thermal shock but by wiping out much of their food source," he said.
"So you should have a marked fall-off or termination of human populations, and we don't see that," he added.
In spite the debate, experts agree that Earth got a shock to its system 12,900 years ago.
The world was in the middle of thawing out from the last ice age, when the "Younger Dryas event" inexplicably plunged it back into near glacial temperatures. This anomalous period lasted for about 1,300 years.
