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Sat, 20 Jul 2019
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Comets

Fireball

Incoming: Massive house-sized asteroid will fly close to Earth next week

Asteroid
© YouTube
Unlike that false alarm in Hawaii, this potentially cataclysmic piece of news is real: an asteroid between 22 and 68 meters in diameter is going to swing past Earth on January 23 at around 12,300 miles an hour (around Mach 16). It's going to come within 1.1 million miles of Earth, but it's unclear whether its trajectory will cause it to hit Earth or fly past harmlessly.

The asteroid, named 2018 AJ, is just one of several asteroids that have suddenly popped up on NASA's radar without warning-the last one was 2017 YD7, which was spotted December 28 and flew past Earth on January 3.

The scary thing about these rocks is that once we spotted them, there's very little we can do to stop them: according to NASA's Planetary Defense Coordination Office, we'd need a few decades of advance warning to deal with an asteroid 100 meters in size or larger. From there, a couple options open up, including knocking the asteroid off course with a "kinetic impactor" or using a "gravity tractor" to change its trajectory.

Comet 2

Dynamic space: Rotation of Comet 41P makes inexplicably slows down

Comet 41P
© Chris Schur/Schurs Astrophotography
Comet 41P/Tuttle-Giacobini-Kresák glides beneath the galaxy NGC 3198 on March 14, 2017, two weeks before the object's closest approach to Earth.
National Harbor, Md. - A small comet broke a rotation-speed record in a big way: New work reveals that an icy rock known as 41P dramatically slowed its spin at an unprecedented rate in 2017, spinning down at about 10 times the pace of the next-ranked comet.

This comet, whose full name is 41P/Tuttle-Giacobini-Kresák, experienced "the largest but also the fastest change that has ever been seen in a comet rotation," said Dennis Bodewits, an associate research scientist at the University of Maryland (UMD) in College Park.

Bodewits presented his team's findings Wednesday (Jan. 10) during a press conference held here at the 231st meeting of the American Astronomical Society.

Comment: What could have acted on it? It need not have been something it came close to. And they used to say space was 'stable'...


Info

Large ancient impact event discovered in Southeast Asia

Impact on Earth
© John R. Foster/Science Source
An artist’s representation of a large impact on Earth.
A kilometer-size asteroid slammed into Earth about 800,000 years ago with so much force that it scattered debris across a 10th of our planet's surface. Yet its impact crater remains undiscovered. Now, glassy remains believed to have come from the strike suggest the asteroid hit southeast Asia as our close ancestors walked the Earth.

"This impact event is the youngest of this size during human evolution with likely worldwide effects," says Mario Trieloff, a geochemist at the University of Heidelberg in Germany not involved in the research. Large impacts can disrupt Earth's climate by spewing dirt and soot high into the atmosphere, where it can block sunlight for months or even years.

Putative remains from this impact have been found before. Researchers have recovered chunks of glassy debris known as tektites across Asia, Australia, and Antarctica, and their distribution pattern suggests the asteroid struck Southeast Asia: The largest tektites-weighing more than 20 kilograms and presumably ejected the shortest distances from the impact-have been found there.

Comet 2

Did comet impacts kill lots of animals in Alaska?

impact-related microspherules
© Hagstrum et. al/Scientific Reports
To laypeople, the "muck" found in certain areas of Alaska and Yukon is just dirt - dark, silty, often frozen, and full of plant material. To miners, it is somewhat of a nuisance. When dug out and left to thaw, the muck lets loose a fetid stench due to its high organic content. To scientists, however, the muck is a graveyard, and a fascinating one at that. Over the years, thousands of remains of bison, mammoth, horse, musk ox, moose, lynx, lion, mastodon, bear, caribou, and even camel have been uncovered.

More interesting than the mere presence of this zoological gold mine is the actual condition of the remains. Cached inside the frozen mucks for as long as 48,000 years, the remains are remarkably well preserved, with some carcasses mostly intact and effectively mummified. Even more curious, many animals show no signs of predation, scavenging, or decomposition, and despite disarticulated bones, seemed to be in relatively good health at the time of their demise.

This made Jonathan Hagstrum, a research geophysicist at the U.S. Geological Survey, wonder... What killed all of these animals? He and colleagues Richard Firestone, Allen West, James Weaver, and Ted Bunch share an intriguing hypothesis.

They think the seemingly sudden deaths of many of these animals in the Alaskan and Yukon mucks could be explained by airbursts and impacts from comet debris that struck Earth during the Late Pleistocene, between 11,000 and 46,000 years ago. Hagstrum and his colleagues recently presented new evidence for this idea in the journal Scientific Reports.

Fireball

Meteor fireball explodes over Crimea

Meteorite
© an-crimea.ru
A powerful explosion occurred in the sky over the city of Simferopol, the Crimea, on December 26. The origin of the explosion remains unknown; EMERCOM officials are trying to look into circumstances.

Local residents have posted a few photos taken in first minutes after the explosion. The photos depict a white trail in the sky, which usually remains behind a flying plane, but it is not straight.

Some people assumed that the explosion could be related to fighter aircraft and their aerobatic stunts.

Comet 2

Halley's comet and the calendar

Heinsohn Horizon
© Malaga Bay
When Europe started carving up the world the acolytes of empire started carving up history to support their beliefs and interests.

By 1850 the acolytes of empire had diced and sliced the Annals of China to create a great and glorious history for Comet Halley all the way back to 11 years before the Christian era.
John Hind
© Malaga Bay
The valuable details existing in the annals of China, and but recently known in Europe, enable us to trace this famous comet with a high degree of probability to the year 11 before the Christian era, - a most important circumstance, not only as regards the history of this particular comet, but as bearing on the constitution of these bodies in general.

On the Past History of the Comet of Halley - J R Hind
Monthly Notices of the Royal Astronomical Society - Vol 10 - Issue 3 - 9 Jan 1850

https://academic.oup.com/mnras/article/10/3/51/2603551
By 1986 the Annals of China [with a little help from the Annals of Babylonia] had provided Comet Halley with a magnificent pedigree stretching all the way back to 240 BC.

Fireball

Meteor fireball lights up night sky over Wisconsin's capital

Meteor over Wisconsin
© YouTube Screen Capture
Cameras outside a University of Wisconsin-Madison facility captured the moment a meteoroid streaked across the night sky.

The University of Wisconsin-Madison's Cooperative Institute for Meteorological Satellite Studies shared footage from a webcam mounted atop the building that captured the fireball's fall from the sky Monday night.


Comet 2

NASA can't save us! Agency misses asteroid as it skims by Earth

asteroid collision
© NASA
A whale-sized asteroid has come frighteningly close to the Earth - within one-third of the distance between the Earth and the moon. What's more, NASA failed to spot the space rock until it had already passed.

The rock is estimated to have a diameter of between six and 32 meters, which would translate into enough destructive power to level a major city. The colossal mass came within 73,000 miles (117,480km) of us in early November.

According to The Watchers, a website that monitors the path of asteroids in our solar system, NASA's Mauna Loa Observatory in Hawaii spotted the asteroid on November 10. However, at that point, it was already heading back out to space after having skimmed the Earth just one day before.

Comment: NASA can't warn us of an asteroid they can't see and using a 'space lasso' to prevent incoming threats probably won't work either. We're on our own, folks!


Comet 2

Comet Dust: Researchers present list of 'pristine' ingredients that make up comet 67P/Churyumov-Gerasimenko

Left: The surface of Rosetta’s comet. As the comet approaches the Sun
© ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA (left), ESA / Rosetta / MPS for COSIMA Team MPS / CSNSM / UNIBW / TUORLA / IWF / IAS / ESA / BUW / MPE / LPC2E / LCM / IMF / UTU / LISA / UOFC / vH & S. (right)
Left: The surface of Rosetta’s comet. As the comet approaches the Sun, frozen gases evaporate from below the surface, dragging tiny particles of dust along with them. Right: These dust grains can be captured and examined using the COSIMA instrument. Targets such as this one measuring only a few centimeters act as dust collectors. They retain dust particles of up to 100 microns in size.
The dust that comet 67P/Churyumov-Gerasimenko emits into space consists to about one half of organic molecules. The dust belongs to the most pristine and carbon-rich material known in our solar system and has hardly changed since its birth. These results of the COSIMA team are published today in the journal Monthly Notices of the Royal Astronomical Society. COSIMA is an instrument onboard the Rosetta spacecraft, which investigated comet 67P/Churyumov-Gerasimenko from August 2014 to September 2016. In their current study, the involved researchers including scientists from the Max Planck Institute for Solar System Research (MPS) analyze as comprehensively as ever before, what chemical elements constitute cometary dust.

Comment: Also See:


Fireball 3

Russian astronomers show big 'unusual orbit' asteroid 3200 Phaethon approaching Earth - UPDATE

Russian Astronomers Show Big Asteroid Approaching the Earth
© CC0/Pixabay
The astronomer community at Immanuel Kant Baltic Federal University used its own Astro-Model simulation environment to produce a virtual image of object 3200 Phaethon approaching the Earth, plus the expected Geminids meteor shower.

December 17, 2017 will see an interesting astronomic event in the form of object 3200 Phaethon approaching our planet. This is a fairly large asteroid nearly 5 kilometers in diameter, which will fly past the Earth within 10 million kilometers, close by space standards.

The asteroid derives its name from its unusual orbit that in perihelia brings it closer to the Sun than any other named asteroid (20 million kilometers). To compare: Mercury, the closest planet to the Sun in the Solar system, is 46 million kilometers from the Sun.


Comment: The activity in our sky is increasing and in the last week or so there have been at least these sightings of meteor-fireballs:

(8th Nov) Bright meteor fireball explodes over northern Germany

(13th Nov) Impressive fireball blazes over Toledo, in the South of Spain (VIDEO)

(14th Nov) 'Blue sphere with green tail' meteor fireball seen over Alsace, France

(15th Nov) Another bright meteor fireball explodes over Germany (VIDEOS)

(15th Nov) Meteor fireball recorded over Ohio

(15th Nov) Fireball streaks across Phoenix sky (VIDEO)

(15th Nov) Bright fireball-meteor lights up sky over San Juan, Argentina

And for a more in-depth look at the recent events check out: (16th Nov) Incoming! Bright bolide explodes over northern Finland (VIDEOS)