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Sat, 27 Aug 2016
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Comets


Fireball 4

Meteorite lands in Leeds garden

© Yorkshire Evening Post
Is it an astronomical gift or something much more mundane? David Stevenson is not sure, but he does know that a glowing hot rock appeared in his Leeds garden, apparently leaving a burning 'impact' site in its wake.

The 46-year-old was at home in Bramley with a friend when in the early hours of the morning he walked outside to the smell of burning. He found a circular area of grass on his lawn, about a metre wide, that was smouldering away and giving off wisps of smoke.

He retired to bed baffled but it was only upon closer inspection in the light of day that he discovered a weighty rock, roughly the size of two tennis balls near to the area of parched ground.

Having dismissed any prank or mischief, Mr Stevenson believes the rock may be a fragment of meteorite that has been sent crashing onto his garden lawn from outer space. His own tests have found it to be magnetic and it was initially giving off enough heat to light a cigarette.

Newspaper

Error or Toddler profiling?: Secretive CA gang database includes 42 babies

© Lucy Nicholson / Reuters
An explosive state audit of a secretive California gang database used by law enforcement showed 42 profiles were for 1-year-old children, half of whom apparently confessed to being in gangs. The database, paid for by taxpayers, is rife with other errors.

Of those profiles for 1-year-old children, 28 were entered for "admitting to being gang members," according to State Auditor Elaine Howle in a statement issued with the report The CalGang Criminal Intelligence System on Friday.

Comet 2

Comets & Asteroids - Summary for July 2016

During the month of July 2016, 1 new comet has been discovered and there were 4 comet recoveries. An international team of astronomers discovered a new dwarf planet (designated 2015 RR245) orbiting in the disk of small icy worlds beyond Neptune. The Team Radar at Arecibo observed the Near-Earth asteroid (154244) 2002 KL6. "Current comet magnitudes" & "Daily updated asteroid flybys" pages are available at the top of this blog (or just click on the underline text here).

The dates below refer to the date of issuance of CBET (Central Bureau Electronic Telegram) which reported the official news & designations.

Comet Discoveries

July 18 Discovery of C/2016 N4 (MASTER)
© Jean-Gabriel Bosch
Comet C/2016 N4 (MASTER).
Comet Recoveries

July 04 Recovery of P/2009 K1 (GIBBS) as P/2016 M2
July 04 Recovery of P/2008 J3 (McNAUGHT) as P/2016 N1
July 06 Recovery of P/2008 T1 (BOATTINI) as P/2016 N2
July 18 Recovery of P/2007 R3 (GIBBS) as P/2016 N3

Comet 2

Brightest Kreutz sungrazer disintegrated by the sun

The sun is about to swallow a comet. The doomed sungrazer appeared earlier today in images from the Solar and Heliospheric Observatory (SOHO):
© ESA/NASA SOHO
"This is one of the brightest Kreutz sungrazers we've seen over the past 21 yrs," says Karl Battams of the Naval Research Lab in Washington DC. "Awesome! "

Kreutz sungrazers are fragments from the breakup of a single giant comet many centuries ago. They get their name from 19th century German astronomer Heinrich Kreutz, who studied them in detail. Kreutz fragments pass by the sun and disintegrate almost every day. Most, measuring less than a few meters across, are too small to see, but occasionally a bigger fragment like this one attracts attention.

The comet is vaporizing furiously and is not expected to survive much longer. Monitor the SOHO realtime images page for developments. Updates are also available on Karl Battam's excellent Twitter feed.


Fireball 3

Fireball spotted over much of Western and Northern California

© KCRA viewer Daniel Miles


KCRA viewer Daniel Miles shared this photo on Wednesday, July 27, 2016.
A streak of light was seen over the eastern sky of Northern California Wednesday night. The light was also seen over Las Vegas, Salt Lake City and Reno.It is unclear what caused the light, which was first spotted around 9:45 p.m.

According to NASA, the Delta Aquarids meteor shower is expected to peak Thursday and Friday. It is also possible the streak was caused by space junk. NORAD and U.S. Strategic Command said they did not know what the streak of light was.

No other details were available.


Comment: Electrically charged meteors can travel very slowly and tend to disintegrate and shed as they do.


Comet 2

Halley's comet orbit being altered by Venus instead of Jupiter

© NASA
Halley’s comet.
If you're waiting for Halley's comet to show up exactly 75 years after its 1986 appearance, you may be disappointed. The ball of ice has an orbit that varies by months or even years.

And new research suggests that Venus is responsible for the comet's variations today, rather than the more massive planet Jupiter.

"Comet Halley has been observed throughout history, all the way back to 240 BC by the Chinese," Tjarda Boekholt, an astrophysicist at Leiden Observatory in the Netherlands, told Discover by email.

Erratic Schedule

With many well-documented appearances, scientists quickly realized that the arrival time of the comet was constantly changing. For instance, although it passed Earth in February in 1986, it won't be back until February 2061. In 45 years, it will instead appear in July.

"It is the variation in the time of sightings that provided the first clue to comet Halley's chaotic orbit," Boekholt said. "The orbit of comet Halley is not static, but it is evolving."

Boekholt led a team that investigated the comet's changing orbit. They found that Venus played an important role in revising the comet's orbit in the past, and will probably continue to do so in the future, despite its small stature. Mighty Jupiter often dominates the influence of gravitational bodies due to its high mass, but Venus currently dominates Halley's is movements.

The research will be published in the journal The Monthly Notices of the Royal Astronomical Society. A preprint is available online.

Fireball

Huge fireball seen across North Western Australia

© [email protected]
A fireball is caused by a large object entering Earth's atmosphere.
People across the Kimberley have reported seeing a bright fireball streak across the sky, inspiring awe and some fear.

"It was scary, because it came from the airport direction, and then we realised that it was probably space junk or a meteor," talkback caller Monica from Broome told ABC Radio.

"We spend a lot of nights with the kids lying out on trampolines watching shooting stars, but I've never seen anything like that."

The fireball was seen across a wide area of north western Australia just before 7pm on Tuesday.

Camped by the Fitzroy River, Cybil called ABC Radio to describe the awe-inspiring sight.

"Huge, big; it was the brightest thing I've ever seen. It was huge, white, massive. I've never seen anything so big in the sky," she said

About 130km south of Broome, Randal was camped on a cliff overlooking the ocean.

"It just seemed to come right up out of the sea, and then shot right across the Barn Hill camping area where we are," he said.

"My wife was sitting opposite me and she spun around, and we watched it disappear over inland somewhere.

"It was just so, so bright. We were wondering whether one of those missiles had come down from North Korea.

"We've seen shooting stars before, but this just outdid anything."

Fireball 2

Great ball of fire over New Zealand

© Otago Times
A fireball that lit up southern skies last night was not a meteor, but something much rarer, a leading astronomer says.

Minutes after the bright orange ball flashed across the sky about 6.30pm, hundreds of people from Dunedin to Nelson took to social media to report having seen it.

Former resident superintendent of Canterbury University's Mt John Observatory Alan Gilmore said the ball of fire had all of the characteristics of a re-entry of debris from a spacecraft, or piece of equipment which had been orbiting Earth.

"It is not a meteor, I'm certain of that. It took too long to go across the sky.''

Comment: Actually, electrically charged meteors CAN travel very slowly. AND, disintegration - shedding - is quite common.


Fireball 3

Two meteorites fell at the exact same spot millions of years apart

© Morocco World News
Rabat - Evidence found in the High Atlas Mountains suggests that two meteors fell in the exact same place, potentially millions of years apart. Seven scientists from an international team lead by a researcher at the Hassan II University in Casablanca studied the impact site and found that the impact structure is much older than the meteorite fragments found at the site.

Large meteorites are not decelerated by the atmosphere, so may create impact structures or "shatter cones" when they land. Meteorites are not usually found at impact sites because they are molten or vaporized upon impact, and they are rapidly eroded or broken down by Earth's environment.

This particular site, outside the Village of Agoudal in the High Atlas Mountains, had meteorite fragments at the site, and it was assumed that the meteorite fragments created the impact structure. The new research, which was published by Professor Hasnaa Chennaoui Aoudjehane and the research team in the science journal Meteoritics and Planetary Science on June 2016, claims that the impact structure was already present when a second meteor hit the same spot, leaving behind the fragments.

The estimated diameter of the original impact structure is between 1 and 3 km. Scientists used the average rate of erosion in the High Atlas Mountains to estimate how old the structures are. Based on how much the structure wore down over time, the impact structure is probably 1.25 to 3.75 million years old. This makes the impact structure much older than the meteorite fragments found in the same site.

Discoveries like this can help scientists better understand the impact of a meteor falling to Earth. Research will continue to determine how life in the region was affected at the time of the impact.

Fireball 3

Evidence of huge asteroid impact event found in Australia

© A Glikson
Impact spherules.
Scientists have found evidence of a huge asteroid that struck the Earth early in its life with an impact larger than anything humans have experienced.

Tiny glass beads called spherules, found in north-western Australia were formed from vaporised material from the asteroid impact, said Dr Andrew Glikson from The Australian National University (ANU).

"The impact would have triggered earthquakes orders of magnitude greater than terrestrial earthquakes, it would have caused huge tsunamis and would have made cliffs crumble," said Dr Glikson, from the ANU Planetary Institute.

"Material from the impact would have spread worldwide. These spherules were found in sea floor sediments that date from 3.46 billion years ago."

The asteroid is the second oldest known to have hit the Earth and one of the largest.

Dr Glikson said the asteroid would have been 20 to 30 kilometres across and would have created a crater hundreds of kilometres wide.

About 3.8 to 3.9 billion years ago the moon was struck by numerous asteroids, which formed the craters, called mare, that are still visible from Earth

"Exactly where this asteroid struck the earth remains a mystery," Dr Glikson said.