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Thu, 05 Dec 2019
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Comets

Comet 2

Comet 67P surprises scientists with 'bright outbursts', collapsing cliffs and rolling boulders during Rosetta mission

comet 67P/Churyumov–Gerasimenko
© Rosetta/NASA
Bouncing boulder on comet 67P/Churyumov–Gerasimenko
It seems that comet 67P/Churyumov-Gerasimenko is not the stoic, unchanging Solar System traveller that it might seem to be. Scientists working through the vast warehouse of images from the Rosetta spacecraft have discovered there's lots going on on 67P. Among the activity are collapsing cliffs and bouncing boulders.

Rosetta spent almost two years at 67P, ending its mission with a hard landing on the comet's surface. During the spacecraft's journey and its two years at the comet, it captured almost 100,000 images. About 3/4 of them are from OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) and the rest are from the NAVCAM. (You can enjoy archives of its images here.)

These images are all being analyzed by scientists, and part of that analysis involves images from during and after perihelion. Perihelion is when an object is closest to the Sun, and scientists expect to see the most changes on the comet during that time. By comparing perihelion images with those following perihelion, they hope to gain a better understanding of how the comet evolves.

Comment: In Did Earth 'Steal' Martian Water? Pierre Lescaudron provides insight into why these events on Comet 67P occurred, particularly as it approached the Sun:
Interplanetary Electric Discharge

The Electric Universe theory, as described in our book Earth Changes and the Human Cosmic Connection, shows how celestial bodies (planets, stars, moons, comets, etc) are electrically charged. In addition, such bodies are surrounded by a sort of "insulation bubble" (Double Layer).

When two astronomical bodies, like two planets, get close enough, an electric discharge forms from the most negative planet to the most positive one, in order to re-balance the electric charge of the two planets. Electric discharges between celestial bodies have been observed several times.
See also: And check out SOTT radio's:


Blue Planet

Did Earth 'Steal' Martian Water?

Mars earth plasma discharge
While finalizing the writing of the article titled "Of Flash Frozen Mammoths and Cosmic Catastrophes", I encountered an unexpected anomaly.

The time of the demise of the mammoths is also known as the Younger Dryas, a period of global cooling that lasted from 12,900 to 11,700 years ago (10,900 B.C. to 9,700 B.C.) during which surface temperatures dropped by approximately 7°C.

In theory, such a severe cooling should increase the volume of polar ice and, as a result, reduce sea level. However, during the Younger Dryas, sea levels rose 17 meters over more than a millennium, as illustrated by the graph below.
Sea level VS global temperature (20000BP-Now)

Sea level VS global temperature (20000BP-Now)
If the sea level rose while ice caps were building up, it's possible that the source of the water was external. But where could this water have come from?

Coincidentally or not, most of Mars' Northern hemisphere was once covered with water, and this ocean has mysteriously disappeared. So where did the Martian water go?

Info

Another possible interstellar comet headed our way in July 2020

Astronomers have discovered a potentially interstellar comet — the second after 'Oumuamua — and it's approaching the Sun, with a perihelion in mid-2020.
Oumuamua
© Universe Today
First there was 'Oumuamua. Now we might be in store for another interstellar flyby, this time by the recently discovered comet A/2019 Q1. Gennady Borisov captured the object on August 30, 2019, at the Crimean Astrophysical Observatory when it was about 5.5 astronomical units (a.u.) from the Sun. Unlike 'Oumuamua, which was discovered well after perihelion, the new comet is approaching the plane of the solar system and will reach perihelion on July 24, 2020 at a distance of 4.96 a.u., about the distance between Jupiter and the Sun.

But it's still early. Don't be surprised if these dates change as more observations come in.

What sets A/2019 Q1 apart from nearly every other comet is the eccentricity of its orbit. Eccentricity measures how much an orbit deviates from a perfect circle, which has an eccentricity of 0. Elliptical orbits, typical of planets, asteroids and comets, have eccentricities between 0 and 1. Parabolas are equal to 1, and an eccentricity greater than 1 indicates a hyperbolic orbit.
Object Orbit
© Stamcose / CC BY-SA 4.0 with additions by the author
How flat an object's orbit is called its eccentricity. An object on a hyperbolic orbit is likely from beyond the solar system.

Fireball

Asteroid changes color and sprouts comet-like tail

Asteroid 6478 Gault
© NASA, ESA, K. Meech and J. Kleyna, O. Hainaut
The asteroid 6478 Gault is seen with the NASA/ESA Hubble Space Telescope, showing two narrow, comet-like tails of debris that tell us that the asteroid is slowly undergoing self-destruction. The bright streaks surrounding the asteroid are background stars. The Gault asteroid is located between the orbits of Mars and Jupiter.
Last December, scientists discovered an "active" asteroid within the asteroid belt, sandwiched between the orbits of Mars and Jupiter. The space rock, designated by astronomers as 6478 Gault, appeared to be leaving two trails of dust in its wake — active behavior that is associated with comets but rarely seen in asteroids.

While astronomers are still puzzling over the cause of Gault's comet-like activity, an MIT-led team now reports that it has caught the asteroid in the act of changing color, in the near-infrared spectrum, from red to blue. It is the first time scientists have observed a color-shifting asteroid, in real-time.

"That was a very big surprise," says Michael Marsset, a postdoc in MIT's Department of Earth, Atmospheric and Planetary Sciences (EAPS). "We think we have witnessed the asteroid losing its reddish dust to space, and we are seeing the asteroid's underlying, fresh blue layers."

Marsset and his colleagues have also confirmed that the asteroid is rocky — proof that the asteroid's tail, though seemingly comet-like, is caused by an entirely different mechanism, as comets are not rocky but more like loose snowballs of ice and dust.

"It's the first time to my knowledge that we see a rocky body emitting dust, a little bit like a comet," Marsset says. "It means that probably some mechanism responsible for dust emission is different from comets, and different from most other active main-belt asteroids."

Marsset and his colleagues, including EAPS Research Scientist Francesca DeMeo and Professor Richard Binzel, have published their results today in the journal Astrophysical Journal Letters.

Fireball

Bright meteor fireball streaks over Edmonton, Canada

Rain wasn't the only thing falling in our city this evening, social media was flooded with reports of a sighting of what appears to be a meteor over Edmonton.
Blazing Meteor
© Pete Saloutos

Comment: More views from social media:



The American Meteor Society (AMS) received 106 reports about the meteor fireball, which was seen over Alberta, MT and Saskatchewan on Sunday, September 1st 2019 around 04:28 UT.

"This fireball would have been seen for 600km from either side of it, probably," said Mike Hankey, operations manager for the American Meteor Society, who speculated that the object was likely a bolide, a very bright meteor, based on the reports he has received.

The meteor spectrum ranges from meteor, to fireball, to bolide and super bolide, which is brighter than the Moon and almost as bright as the Sun.


Comet 2

Dr. Napier fingers fragmented comet in Younger Dryas and Bronze Age impacts

Comet 332P Fragmenting
© NASA, ESA, D. Jewitt (UCLA)
This image, captured on January 27 2016 by the Hubble Space Telescope, is one of three showing Comet 332P fragmenting as it nears the sun.
Folks, I am sorry to have been so scarce in recent months. Among other excuses for the inexcusable, the auto-mailer for subscribers to the site went down, and I felt I needed to repair it before posting. Fixing it turned into a mess which led to my continued procrastination. Much has happened in recent months in our subject though, and I look forward to catching up and posting more, as the year closes out.

First up is a fabulous new paper from Tusk friend and Scottish astronomer William Napier. Bill is a member of the Comet Research Group and contributes his world class knowledge on the behavior of comets in support of the Younger Dryas Impact Hypothesis. In this contribution he further refines the culprit in our favorite cataclysm, a fragmenting comet. But keep in mind, as sometimes others have not, that the subject comet is fragmenting IN SPACE over thousands of years, not in the earth's atmosphere. See The Bos misdirecting the nature and context of the fragmentation events here and here, and the CRG response here.

Meteor

It's called Apophis. It's 390m wide. And it could hit Earth in 31 years time

apophis asteroid
In Egyptian myth, Apophis was the ancient spirit of evil and destruction, a demon that was determined to plunge the world into eternal darkness.

A fitting name, astronomers reasoned, for a menace now hurtling towards Earth from outerspace. Scientists are monitoring the progress of a 390-metre wide asteroid discovered last year that is potentially on a collision course with the planet, and are imploring governments to decide on a strategy for dealing with it.

Nasa has estimated that an impact from Apophis, which has an outside chance of hitting the Earth in 2036, would release more than 100,000 times the energy released in the nuclear blast over Hiroshima. Thousands of square kilometres would be directly affected by the blast but the whole of the Earth would see the effects of the dust released into the atmosphere.

Comment: 15 years later, they're still reporting about Apophis as if it's breaking news.

As we said at the time...

sott.net meteor fireballs



Info

Lascaux Shaft Scene and cometary impacts

The Lascaux shaft scene is perhaps the most iconic of all European Palaeolithic cave artworks (see below). It shows a bison and human, apparently both dying and normally interpreted as a hunting scene. But we now know, beyond any reasonable doubt, the animal symbols represent constellations, and the Shaft Scene in particular very likely represents a date using precession of the equinoxes.
Lascaux Shaft Scene
© Copy of the Lascaux Shaft Scene, courtesy of Alistair Coombs
Using the zodiacal method and our ancient zodiac, the date 'written' in the scene is between 15,300 and 15,000 BC (see Prehistory Decoded). The similarity of this scene to Pillar 43 at Gobekli Tepe suggests it documents another asteroid or comet strike, this time from the direction of Capricornus (represented by the aurochs). It so happens that the Taurid meteor stream would rave radiated from this direction at this time, suggesting this artwork memorialises another strike from the Taurid system. Given the presence of a giant comet in the inner solar system at this time, such frequent impacts are entirely expected.

Very interestingly, this time span also corresponds to a sudden temperature fluctuation in the North Atlantic region (see Prehistory Decoded), documented by a Greenland ice core, and to a major cultural transition: the Magdalenian to Azillian.

Fireball 5

Perseids meteor shower to peak Monday night with stunning FIREBALL displays

Perseids meteor shower
© NASA/Ron Garan (@Astro_Ron)
Perseid meteor shower as seen from the International Space Station
It's that time of year again, when the spectacular Perseid meteor shower rains fire across the night sky. The days-long fireball fiesta is expected to peak this evening with an estimated 80 shooting stars per hour at its height.

Widely seen as one of the most entertaining celestial events of the year, the Perseids meteor shower is caused by meteoroids from the debris trail of the Comet 109P/Swift-Tuttle which orbits the sun once every 133 years.

Those in the Northern Hemisphere will be treated to the best views, provided they can escape the light pollution from towns and cities. The moon will frustrate proceedings somewhat as a full moon is due on Thursday, meaning the sky will likely be washed out for the majority of viewers, but fear not, as the Perseids have an ace up their sleeve.

Instead of shooting stars, stargazers can hunt for bright 'fireballs' which can last up to a second rather than merely fractions of a second like their shooting star brethren.

"...[T]he Perseids are rich in bright meteors and fireballs, so it will still be worth going out in the early morning to catch some of nature's fireworks," NASA says.

Fireball 4

'I thought it was Armageddon' - Perth residents stunned by early morning meteor fireball

Early risers around the Perth metropolitan area were stunned by a bright green light filling the night sky on Wednesday morning, but what looked like Armageddon was most likely a meteor, according to a Perth Observatory staffer.
Meteor Fireball
© Brisbane Times
Just before 6am 6PR News director Lisa Barnes was out for her morning run near Ellenbrook when she saw the phenomenon light up the sky.

"It was so amazing to see, it lit up the whole sky, a quick flash of light and then it drew my eyes to where I was heading (...) and then it was like a ball of light and I watched it fall."

Mrs Barnes said it was much bigger and brighter than a shooting star.