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Tue, 17 Sep 2019
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Comets

Comet 2

Earth may be in the middle of a giant asteroid spike

Impact Craters on the Moon
© Dr. A Parker/Southwest Research Institute
Impact craters on the moon reveal that the number of asteroid impacts increased dramatically over the last 300 million years. Here, a map of all the impact craters larger than 6 miles (10 kilometers) in diameter and younger than 1 billion years old.
Like a motorcycle windshield splattering bugs on the highway, Earth's atmosphere is constantly deflecting tiny bits of extraterrestrial rock, dust and other space garbage that get in the way of our planet's 67,000-mph (107,000 km/h) joyride. Occasionally, that debris breaks through - as it did 66 million years ago, when an asteroid the size of Manhattan crashed into the Gulf of Mexico and killed the dinosaurs.

That impact was singularly catastrophic. But, according to a new study published today (Jan. 17) in the journal Science, that smashup was also just one episode in an ongoing spike of gargantuan asteroid impacts bombarding our neck of the solar system. After studying 1 billion years of asteroid craters on the Earth and moon, the study's authors found that the rate of huge asteroid impacts on Earth has nearly tripled in the past 290 million years - and nobody's sure why.

"It's perhaps fair to say it was a date with destiny for the dinosaurs," study co-author Thomas Gernon, associate professor of Earth science at the University of Southampton in the U.K., said in a statement. "Their downfall was somewhat inevitable given the surge of large space rocks colliding with Earth."

Comet 2

Oumuamua data reveals intriguing possibilities

Oumuamua
© M. Kornmesser/European Southern Observatory
Today, physicist Eugene Bagashov concludes his remarkable three-part analysis of Oumuamua, the mysterious object which is thought to be our solar system's first interstellar traveler. In previous episodes, Eugene has explored several enigmas, including the puzzle of the object's mysterious acceleration as it moved away from the Sun. While this episode was in production, Eugene made a stunning discovery that may provide an essential pathway to understanding Oumuamua's trajectory. As Eugene explains, this discovery relates directly to measurements of the interstellar magnetic field.

Info

Greenland Crater - The 12,000 year old comet that erased ancient civilization

Ancient Impact
© ScreenCapture/YouTube
NASA recently discovered of a massive, 19-mile (31km) wide crater, found hidden underneath Greenland's Hiawatha Glacier. This crater is the result of an asteroid impact, from a nearly 1 mile-wide mountain of iron, weighing somewhere around, get this, 11-12 BILLION tons, and was traveling at approximately 12 MILES per second - which is equivalent to more than 43,000 miles per hour - when it slammed into the earth some 12,000 years ago - And...with the mind-boggling force of essentially a 700-megaton bomb. And without a doubt, THIS is the reason why there is so much mystery and why we know so little about lost Ancient human civilization

Meteor

Earth enters densest stream of deadly Taurid meteor cluster this June

asteroid Bennu
© (NASA/Goddard/University of Arizona/AP) By Joel Achenbach December 25
This mosaic image collected on Dec. 2 and provided by NASA shows the asteroid Bennu, which is being studied by the NASA probe Osiris-REx. Bennu regularly crosses Earth's orbit and will pass close to our planet in about 150 years.
Incoming! A June meteor swarm could be loaded with surprises. Scientists studying a mysterious event over Siberia in 1908 call for a special observation campaign next summer.

On June 30, 1908, an object the size of an apartment building came hurtling out of the sky and exploded in the atmosphere above Siberia. The Tunguska event, named for a river, flattened trees for 800 square miles. It occurred in one of the least-populated places in Asia, and no one was killed or injured. But the Tunguska airburst stands as the most powerful impact event in recorded human history, and it remains enigmatic, as scientists don't know the origin of the object or whether it was an asteroid or a comet.

One hypothesis: It was a Beta Taurid.

The Taurids are meteor showers that occur twice a year, in late June and late October or early November. The June meteors are the Betas. They strike during the day, when sunlight washes out the "shooting stars" that are visible during the nighttime meteor shower later in the year.

Comment: Scientists should be held accountable for propagating such ignorance and wishful thinking. The threat of cyclical cometary catastrophes is very real, it has been well documented by peoples throughout history and it is clearly evident in the archaeological record: And to hear what the historical records have to say on the matter, check out SOTT radio's: Behind the Headlines: Who was Jesus? Examining the evidence that Christ may in fact have been Caesar!


Comet 2

New Comet C/2018 Y1 (Iwamoto)

CBET 4588 & MPEC 2018-Y52, issued on 2018, Dec. 20, announce the discovery of a comet (magnitude ~12) by M. Iwamoto (MPC code 872) in images taken on 2018 Dec 18.8. The new comet has been designated C/2018 Y1 (Iwamoto).

I performed follow-up measurements of this object, while it was still on the PCCP webpage. Stacking of 5 unfiltered exposures, 20 seconds each, obtained remotely on 2018, December 20.5 from H06 (T20 - iTelescope network) through a 0.1-m f/5.0 astrograph + CCD, shows that this object is a comet with a diffuse coma about 1.5 arcmin in diameter and sharp central condensation.

My confirmation image (click on it for a bigger version)
Comet C/2018 Y1 (Iwamoto)
© Remanzacco Blogspot
MPEC 2018-Y52 assigns the following preliminary parabolic orbital elements to comet C/2018 Y1: T 2019 Jan. 27.16; e= 1.0; Peri. = 354.05; q = 1.14; Incl.= 160.69

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.