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Sat, 15 Dec 2018
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Comets


Fireball 2

Geminid fireball filmed buzzing comet Wirtanen

comet wirtanen fireball
© Joe Lawton
The radiant of the Geminid meteor shower is not very far from approaching Comet 46P/Wirtanen. Their respective constellations, Gemini and Taurus, are next door neighbors. That means comet photographers can expect to catch some Geminids in their exposures. Indeed, that's exactly what happened to Joe Lawton of Gerald, Missouri, on Dec. 9th. "As I was photographing 46P/Wirtanen, a Geminid meteor blazed across the sky and disintegrated next to the comet!"

"I combined a series of still images to create this video," he explains. "You can see smokey debris from the Geminid meteoroid twisting in the winds of the upper atmosphere and ultimately dissipating."

How often is this happening? Just last night Harlan Thomas of Powderface Trail, Alberta, and Dr. Paolo Candy of the Cimini Astronomical Observatory in Italy also caught Geminids streaking past the comet.

Comment: With the arrival of the Geminids, and even a week or so before, fireball sightings, have risen rather dramatically:


Fireball 5

Video simulations show what would happen if asteroids crashed into Earth's oceans

Asteroid Impact Simulation
© YouTube/NCAR VisLab
In films like Armageddon, Hollywood has tried (and failed) to take on the question of what would happen if a comet or asteroid plunged into the oceans on Earth, but what has scientific research actually determined it may look like?

America's National Center for Atmospheric Research (NCAR) has posted a new video illustrating what could happen if an asteroid crashed into one of our oceans, and it's fascinating.

Based on data collected by Los Alamos National Laboratory scientists Galen R. Gisler and John M. Patchett, referred to as the Deep Water Impact Ensemble Data Set, these simulations show asteroids of various sizes entering the water from different angles. It's the scale and size of the aftermath that's the truly stunning part.


Comet 2

Newly discovered supernova complicates origin story theories

Supernova ASASSN-18bt
© Carnegie Institution for Science
Six images showing the host galaxy of the newly discovered supernova ASASSN-18bt. The top row shows three images from before the explosion taken by Pan-STARRS, ASAS-SN, and Kepler. The bottom row shows images from ASAS-SN and Kepler after the supernova was visible. The discovery image from the ASAS-SN team is in the bottom middle. To its left is a version with all the surrounding stars eliminated, showing only the new supernova’s light output. On the bottom right is a Kepler image from after the supernova was detected. Kepler’s precision was crucial to understanding the light from ASASSN-18bt in the early hours after the explosion.
Pasadena, CA - A supernova discovered by an international group of astronomers including Carnegie's Tom Holoien and Maria Drout, and led by University of Hawaii's Ben Shappee, provides an unprecedented look at the first moments of a violent stellar explosion. The light from the explosion's first hours showed an unexpected pattern, which Carnegie's Anthony Piro analyzed to reveal that the genesis of these phenomena is even more mysterious than previously thought.

Their findings are published in a trio of papers in The Astrophysical Journal and The Astrophysical Journal Letters. (You can read them here, here, and here.)

Type Ia supernovae are fundamental to our understanding of the cosmos. Their nuclear furnaces are crucial for generating many of the elements around us, and they are used as cosmic rulers to measure distances across the universe. Despite their importance, the actual mechanism that triggers a Type Ia supernova explosion has remained elusive for decades.

That's why catching them in the act is crucial.

Astronomers have long tried to get detailed data at the initial moments of these explosions, with the hope of figuring out how these phenomena are triggered. This finally happened in February of this year with the discovery of a Type Ia supernova called ASASSN-18bt (also known as SN 2018oh).

Info

Giant impact crater found under Greenland ice, possibly 12,000 years old - UPDATE

Greenland impact crater
© Kjær, et al
The Greenland impact crater, superimposed over Paris.
Scientists have discovered a crater beneath Greenland's Hiawatha Glacier that they say could be one of the 25 largest impact structures on Earth.

It's a 31-kilometre-wide circular bedrock depression up to a kilometre below the ice and was likely caused by a fractionated iron asteroid about a kilometre wide.

Its impact would have had substantial environmental consequences in the Northern Hemisphere and perhaps even more widely, say the researchers, led by led by Kurt Kjær from the University of Copenhagen, Denmark.

The crater is the only one of its size that retains a significant portion of its original surface topography.


Comment: The Guardian reports a few more intriguing details:
Crater appears to be result of mile-wide iron meteorite just 12,000 years ago

Nasa/Cryospheric Sciences Lab/Natural History Museum of Denmark

An illustration of the ice-filled crater discovered in Greenland.
A huge impact crater has been discovered under a half-mile-thick Greenland ice sheet.

The enormous bowl-shaped dent appears to be the result of a mile-wide iron meteorite slamming into the island at a speed of 12 miles per second as recently as 12,000 years ago.

The impact of the 10bn-tonne space rock would have unleashed 47m times the energy of the Little Boy nuclear bomb dropped on Hiroshima in 1945. It would have melted vast amounts of ice, sending freshwater rushing into the oceans, and blasted rocky debris high into the atmosphere.

At 19.3 miles wide, the crater ranks among the 25 largest known on Earth and is the first to be found beneath an ice sheet.

"You have to go back 40 million years to find a crater of the same size, so this is a rare, rare occurrence in Earth's history," said Kurt Kjær, of the Natural History Museum of Denmark in Copenhagen.

Scientists first suspected a crater in 2015 when they spotted a huge depression in Nasa radar images of the bedrock beneath the Hiawatha glacier in north-west Greenland. Kjær, who passes a 20-tonne meteorite to reach his office every day, wondered if such a space rock might be the culprit. "It all snowballed from there," said Joseph MacGregor, a senior scientist on the team at Nasa's Goddard Space Flight Center in Maryland.

greenland crater
It so happened that researchers at the Alfred Wegener Institute in Germany were about to test a powerful new ice-penetrating radar system that was operated from the air. In May 2016 the scientists flew over the Hiawatha glacier and used the radar to map the underlying rock in unparalleled detail.

The images revealed all the hallmarks of an impact crater. "It became very clear that this was a circular feature with a rim around it and an elevated central region," said Kjær. The basin itself was more than 300 metres deep, according to a report in the journal Science Advances.

To search for solid proof of an impact, the researchers flew out to the glacier and collected sediments that had washed from the crater on to a nearby floodplain. Among the gathered grains, the scientists found particles of shocked quartz and other materials that are typically produced by the violence of a extraterrestrial impact. Geochemical tests of the grains suggest the meteorite was made of iron.

So far it has been impossible to put a firm age on the crater, but its condition suggests it formed after ice began to cover Greenland about 3 million years ago. But the crater may have formed much more recently. The radar images show that while the surface layers of the glacier immediately above the crater look normal, deeper layers that are older than 12,000 years are badly deformed and strewn with rocks, with some lumps as big as trucks.

"When it happened is the $64,000 question," said MacGregor. For a final answer, the researchers will need to drill through half a mile of ice and collect crater material for dating, or wait for rocks from the impact basin to be brought to the surface as the glacier flows to the sea. Either way, the scientists have a wait on their hands.

"We live on a planet where you can survey anything and you think you know everything," said Kjær. "But when you see such a big thing as this hiding in plain sight, you realise that the age of discovery is not over yet."
And for more on the evidence of what was happening back then, check out: Of Flash Frozen Mammoths and Cosmic Catastrophes


Comet 2

New Comet C/2018 V1 (Machholz-Fujikawa-Iwamoto)

3Day Orbit
© NASA
CBET 4569 (issued on 2018, November 08) and MPEC 2018-V151 (2018, November 11), announce the discovery of a 10th-magnitude comet by Donald E. Machholz (Colfax, CA, U.S.A) and independently by Shigehisa Fujikawa (Kan'onji, Kagawa, Japan) and Masayuki Iwamoto(Awa, Tokushima, Japan).

The new comet has been designated C/2018 V1 (Machholz-Fujikawa-Iwamoto).

- D. Machholz reported his VISUAL DISCOVERY on Nov. 7.531 UT with a 0.47-m reflector (113x). He also observed the comet with similar appearance on Nov. 8.533

- Shigehisa Fujikawa found the object (with no description provided) on Nov. 7.82 UT on a CCD image obtained with a 120-mm-f.l. f/3.5 lens. His discovery was reported to the Central Bureau's TOCP webpage, which produced the provisional designation TCP J12192806-0211143.

- Masayuki Iwamoto discovered the new object on images obtained on Nov. 7.841 with a 10-cm f/4.0 Pentax SDUF II telephoto lens and a Canon EOS 6D camera; Iwamoto called it a possible comet of mag 10 with approximate position R.A. = 12h19m30s, Decl. = -2d11' (equinox 2000.0) and his observations was reported on TCP J12192806-0211143 TOCP webpage. He added that he also observed it one minute later and detected no movement.

Prompted by the Iwamoto's remark in the TOCP webpage about the possible cometary nature of this transient I decided to perform follow-up measurements of this object. The telescope I chose was T14 astrograph in New Mexico due to its wide field FOV (155.8 x 233.7 arc-mins). In fact as only 1 astrometric position was available at that time and my observation was scheduled 16 hours after it was taken, in case of a comet it was important to have as much field as possible around that only reported astrometry point.

As it happens, it was a comet and I found it about 51 arcmin from the reported astrometry available (60 arcmin is 1 degree). Single unfiltered 60 second exposure, obtained remotely on 2018, November 08.5 from H06 (iTelescope network) through a 0.10-m f/5 reflector + CCD, shows that this object is a comet with a diffuse coma about 2 arcmin in diameter.

Comet 2

Czech Mate - Confirmation of the Younger Dryas impact event

Gunther Kleteschka
© The Cosmic Tusk
See another blockbuster confirmation of the Younger Dryas cosmic impact below. I keep a pretty close eye on our subject but had no idea such intricate, original and thorough work was underway in the Czech Republic. Gunther Kleteschka has appeared on several YDB papers, but has clearly been busy in his own laboratory collecting entirely new, informative and well dated expressions of the YDB boundary in lake sediments. His work and that of his local colleagues is clearly exciting and in keeping with the predictions made by the Younger Dryas Impact Hypothesis.

Cosmic-Impact Event in Lake Sediments from Central Europe Postdates the Laacher See Eruption and Marks Onset of the Younger Dryas

Gunther Kletetschka,1,2,3,* Daniel Vondrák,4 Jolana Hruba,2 Vaclav Prochazka,2 Ladislav Nabelek,1,2 Helena Svitavská-Svobodová,5 Premysl Bobek,5 Zuzana Horicka,6,7 Jaroslav Kadlec,8 Marian Takac,2 and Evzen Stuchlik7

Institute of Geology, Czech Academy of Sciences, CZ-252 43 Průhonice 770, Czech Republic; 2. Institute of Hydrogeology, Engineering Geology and Applied Geophysics, Charles University, Albertov 6, CZ-128 43 Prague 2, Czech Republic; 3. Geophysical Institute, University of Alaska Fairbanks, 903 North Koyukuk Drive, Fairbanks, Alaska 99775-7320, USA; 4. Institute for Environmental Studies, Charles University, Benátská 2, CZ-128 01 Prague 2, Czech Republic; 5. Institute of Botany, Czech Academy of Sciences, Zámek 1, CZ-252 43 Průhonice, Czech Republic; 6. Branch of Applied Ecology, T. G. Masaryk Water Research Institute, Podbabská 30, CZ-160 00 Prague 6, Czech Republic; 7. Institute of Hydrobiology, Biology Centre, Czech Academy of Sciences, Na Sádkách 7, CZ-370 05 České Budějovice, Czech Republic; 8. Institute of Geophysics, Czech Academy of Sciences, Boční II 1401, CZ-141 31 Prague 4, Czech Republic

Comment: Of Flash Frozen Mammoths and Cosmic Catastrophes


Crusader

Witches, Comets and Planetary Cataclysms

witch1
© Dot Connector Magazine
When you think of Halloween, what is the first image that comes to mind? I took a little informal poll among my friends, family and associates. Guess what image came in first? Jack-o-lanterns! Bet you thought I was going to say "witches". Well, I sure thought it would be witches, but they only came in a close second!..

When I think of Halloween, I think of grade-school art projects where we cut out silhouettes of witches to paste onto large yellow moons made of construction paper. The witch was always on a broom with her black dress flying in the wind, accompanied by a black cat sitting on the back of the broom. I wondered even then how the cat managed to stay on and why anybody would think that straddling a broomstick as a seat would be even remotely comfortable.

Comet 2

Asteroid Phaethon acts like a comet, contributes to a meteor shower, and it's blue

asteroid
Having studies countless asteroids in near-Earth space, astronomers have come to understand that the majority of these rocks fall into one of two categories: S-type (grey) and C-type (red). These are defined by the types of materials on their surfaces, with S-type asteroids being primarily composed of silicate rock and C-type asteroids being made up of carbon materials.

However, there is also what are known as blue asteroids, which make up only a fraction of all known Near-Earth Objects (NEO). But when an international team astronomers observed the blue asteroid (3200) Phaeton during a flyby of Earth, they spotted behavior that was more consistent with a blue comet. If true, then Phaeton is of a class of objects that are so rare, they are almost unheard of.

The team's findings were presented at the 50th annual meeting of the American Astronomical Society's Division for Planetary Science, which is taking place this week (Oct. 21st to Oct. 26th) in Knoxville, Tennessee. The presentation, titled "Physical Characterization of (3200) Phaethon: Target of the DESTINY+ Mission", was led by Theodore Kareta of the Lunar and Planetary Laboratory (LPL).

Comment: See also:


Comet 2

"Comet of the year" 46P/Wirtanen making close approach, may become visible in December

Comet 46P/Wirtanen
© Yasushi Aoshima
Comet 46P/Wirtanen
Taken by Yasushi Aoshima on October 7, 2018 @ Ishikawa, JAPAN
Astronomers are calling Comet 46P/Wirtanen the "comet of the year." Two months from now, on Dec. 16th, the kilometer-wide ball of dirty ice will come within 11.5 million km of Earth--making it one of the 10 closest-approaching comets of the Space Age. Comet 46P/Wirtanen will probably become a naked eye object for several weeks during the holidays. Here's what it looks like now:

Yasushi Aoshima of Ishikawa, Japan, took the picture using a 12-inch telescope. It shows the comet's green atmosphere which is, impressively, almost twice as wide as the planet Jupiter. The green color comes from diatomic carbon (C2)--a gaseous substance common in comet atmospheres that glows green in the near-vacuum of space.

At the moment, the integrated brightness of the comet is similar to a 10th magnitude star--that is, dim. However, forecasters expect it to brighten more than 200-fold by December. If current trends hold, 46P could ultimately reach magnitude +3, making it not a Great Comet but a very good one, visible to the unaided eye and an easy target for binoculars or small telescopes.

Comment: Close calls are becoming increasingly common, and, while they may be a awesome sight, historically they portend disaster: Also check out SOTT radio's: Behind the Headlines: Who was Jesus? Examining the evidence that Christ may in fact have been Caesar!


Comet 2

5 meteor showers that will light up the night sky this fall

Meteor showers
Autumn is meteor shower season across the Northern Hemisphere with the season's longer nights benefiting those trying to spot a few shooting stars.

The upcoming months feature many minor to moderate meteor showers, but concludes with the Geminids, which features hundreds of multi-colored meteors every night.

Meteor showers occur when the Earth passes through a trail of debris left behind by a comet. The debris is largely just grains of dust that burn brightly when entering the planet's atmosphere.