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Thu, 29 Oct 2020
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Comet 2

Sun swallows newly discovered comet

soho comet sun

A new comet was discovered yesterday, and it's already history. "The first comet discovery of the decade goes to... SOHO!" reports Karl Battams of the Naval Research Lab in Washington DC. During the early hours of Jan. 13th, coronagraphs onboard SOHO (the Solar and Heliospheric Observatory) spotted the tiny comet plunging into the sun, where it rapidly evaporated:

SOHO is the most prolific comet hunter in history. "It's actually quite unusual that it has taken 13 days for SOHO to find a comet," notes Battams. "This is the furthest we've gone into a new calendar year without a discovery since 2008. We're closing in on 3,900 comets discovered, and should comfortably pass 4,000 sometime this year!"

Comment: See also: Volcanoes, Earthquakes And The 3,600 Year Comet Cycle


Ancient impact crater discovered in Southern Laos

Impact Crater
© Shutterstock
An ancient impact scattered bits of glassy debris from Asia to Antarctica, but the resulting crater has long eluded detection.
About 790,000 years ago, a meteor slammed into Earth with such force that the explosion blanketed about 10% of the planet with shiny black lumps of rocky debris. Known as tektites, these glassy blobs of melted terrestrial rock were strewn from Indochina to eastern Antarctica and from the Indian Ocean to the western Pacific. For more than a century, scientists searched for evidence of the impact that created these pitted blobs.

But the crater's location eluded detection — until now.

Geochemical analysis and local gravity readings told researchers that the crater lay in southern Laos on the Bolaven Plateau; the ancient impact was concealed under a field of cooled volcanic lava spanning nearly 2,000 square miles (5,000 square kilometers), the scientists reported in a new study.

When a meteor hits Earth, terrestrial rocks at the impact site can liquefy from the intense heat and then cool into glassy tektites, according to the Jackson School Museum of Earth History at The University of Texas. Scientists can look at the abundance and locations of tektites to help locate an impact, even if the original crater is eroded or concealed, the study authors wrote.

In this case, there were plenty of tektites — so where was the crater?


Jupiter not a shield but is flinging comets toward Earth says new research

Jupiter and the Trojan asteroids
© NASA/JPL-Caltech
Artist’s depiction of Jupiter and the Trojan asteroids.
Some astronomers believe that Jupiter, instead of protecting Earth from dangerous comets and asteroids, is actively flinging objects into the inner solar system. New research now demonstrates this complex process in action.

A popular theory suggests Jupiter, with its tremendous mass, acts like a gigantic shield in space, sucking in or deflecting dangerous debris left over from the formation of the solar system. That makes sense, but the Jupiter Shield theory, as it's known, has been falling out of favour over the past two decades.

A leading critic of this theory, Kevin Grazier, formerly of the West Point U.S. Military Academy and NASA, has sought to debunk this idea for years. He has published several studies on the subject, including a 2008 paper titled, "Jupiter as a Sniper Rather Than a Shield." Indeed, with each successive paper, Grazier has increasingly demonstrated the ways in which Jupiter, instead of being our protector, is actually — though indirectly — a pernicious threat.

Grazier's latest foray into the subject involves a pair of companion papers, one published in the Astronomical Journal in 2018 and the other in the Monthly Notices of the Royal Astronomical Journal in 2019. The first paper takes a look at the complex ways in which objects in the outer solar system are affected by the Jovian planets, namely Jupiter, Saturn, Neptune, and Uranus, while the second paper looks at a specific family of icy bodies and how they're transformed by Jupiter into potentially deadly comets. Looking at the findings of the two papers, it seems the Jupiter Shield theory is in serious jeopardy.

"Actually, I wouldn't say that it's in jeopardy — I would say that it has been laid to rest." Grazier told Gizmodo in an email. "Our simulations show that Jupiter is just as likely to send comets at Earth as deflect them away, and we've seen that in the real solar system."

To be clear, this was a very good thing when the Earth was young, as comets and asteroids delivered the essential ingredients required for life. Today, however, these impacts are most certainly not good, as they could trigger mass extinctions similar to the one that extinguished non-avian dinosaurs some 66 million years ago.

Comet 2

New Comet C/2019 Y1 (ATLAS)

CBET 4708 & MPEC 2020-A72, issued on 2020, January 05, announce the discovery of a comet (magnitude ~18) in the course of the "Asteroid Terrestrial-Impact Last Alert System" (ATLAS) search program, in images taken on 2019, Dec 16 with a 0.5-m reflector + CCD. The new comet has been designated C/2019 Y1 (ATLAS).

I performed follow-up measurements of this object while it was still on the PCCP webpage. Stacking of 28 unfiltered exposures, 30 seconds each, obtained remotely on 2019, December 20.15 from X02 Telescope Live network (El Sauce, Chile) through a 0.6-m f/6.5 reflector + CCD, shows that this object is a comet with a sharp central condensation and a diffuse irregular coma about 15 arcsec in diameter elongated in PA 90.

My confirmation image (click on it for a bigger version)
Comet C/2019 Y1 Atlas
© Remanzacco Blogspot

Fireball 5

Asteroid to fly past Earth on Friday the 13th

Asteroid Flyby
NASA has been monitoring an asteroid which maintains an orbit around various bodies in the solar system and consistently passes through Earth's orbit with the sun. 13 near-Earth objects in total are expected to fly past Earth in December of this year.

Earth is set to have a close encounter with an enormous asteroid which is set to fly nearby Earth on Friday at a speed of almost 18,000 miles an hour (more than 28,000 km/h), according to NASA.

The upcoming pass-by is estimated to happen on 8:25 am on 13 December, the unlucky Friday the 13th. The asteroid's orbit diagram indicates that the near-Earth approach will follow the rock's intersection with Earth's orbit.

According to the space agency's Center for Near-Earth Object Studies (CNEOS), the asteroid has an Earth-crossing orbit with the sun and will not approach from a diagonal or perpendicular direction and instead will flyby perpendicular to earth.

Fireball 3

Near-Earth asteroid numbers grow

It looks like being a busy end to 2019 for asteroid watchers.
People using telescopes to stare at the night sky on December 20 or 26 might see a distant light traversing the heavens, but proclaiming it as a harbinger of a New Testament rerun would be unwise.

The European Space Agency's Near-Earth Object Coordination Centre advises that on neither night will the Star of Bethlehem be visible, but an asteroid very likely will be.

On December 20 a 300-metre-wide rock known as (216258) 2006 WH1 will whizz by. Six days later, (310442) 2000 CH59 - a bit bigger, at 400 metres - will do the same.

There is, however, no cause for alarm, given that both will remain at least 15 times the distance from the Earth to the Moon away. (Any relationship between either and newborn messiahs will thus be coincidental rather than causal.)

This is a rather more comforting route than those taken recently by five 10-metre-wide objects, and a single two-metre object, all of which, the ESA reports, came within half a lunar distance of Earth in the first 10 days of November.


Stars seen slinging comets at Earth for the first time

Night Sky
Stars and comets make unlikely dance partners. Their gravitational partnership is one that astronomers have long suspected but have never seen — until now. For the first time, a Polish group has identified two nearby stars that seem to have plucked up their icy partners, swinging them into orbits around our sun.

The astronomers found the stellar duo after studying the movements of over 600 stars that came within 13 light-years of the sun. The new findings validate a theory born more than a half-century ago, and in doing so have also shown just how rare these stellar dances can be.

Out on the far edge of the solar system, hanging like wallflowers around the planetary dance floor, is the Oort Cloud. This icy group of objects were left over after the formation of the solar system, creating a giant shell enveloping our home system that extends from 66 times the distance to Neptune to 9.23 trillion miles (14.9 trillion kilometers) away from the sun. Astronomers think the Oort Cloud is a reservoir for long-period comets — those that take more than 200 years to orbit the sun. Comet Hale-Bopp, which has a 2,500-year orbit, is one of the most famous of these long-period comets.

Since the cloud's existence was first proposed by Jan Oort in the 1950s, astronomers have suspected that every so often, a passing star might be able to pick up an object and send it swinging on a wild ride through our solar system; that ride would bring some of those comets streaming through the night sky for us to marvel at. Astronomers have spent years trying to find proof of these stellar dances, but none had been conclusively shown until now.

Fireball 2

Volcanoes, Earthquakes And The 3,600 Year Comet Cycle

In two previous articles, I proposed explanations for the events that triggered the Younger Dryas.

In the article titled Did Earth Steal Martian Waters, I described how, ca.12,500 BP, an electric discharge may have transferred part of the Martian water and atmosphere to Earth (see pink arrow on the diagram below).

In the article titled Of Flash-frozen Mammoths and Cosmic Catastrophes, I explained how, about 4 centuries earlier, ca. 12,900 BP, several cometary fragments hit the Earth's Northern hemisphere (see turquoise arrow) causing the subsequent global cooling.

Greenland temperature 18000 BP - now

Greenland temperature 18000 BP - now
While writing those articles it appeared more and more clear that these were only two of three catastrophic events that preceded the Younger Dryas. In the diagram above, we can see that a third event occurred ca. 14,400 BP (see green vertical line).

This event had an even greater magnitude than the two events that followed it since it induced a 10°C drop as compared to the two following events which 'only' induced a 7°C drop.

In the present article, we will explore the specifics of the 14,400 BP event and explain how it might be part of a larger 3,600 year cometary cycle.

Fireball 4

Meteor fireball videoed over Lake Mendota, Wisconsin

Fireball over Lake Mendota
© Madison
Did you see it?

A Sunday morning tweet from NOAA's Cooperative Institute for Meteorological Satellite Studies at the UW-Madison showing a meteor flashing over Lake Mendota drew a host of "oohs" and "ahhhs".


Impact crater in Australia happened far more recently

Wolfe Creek Crater Australia
© Stephan Ridgway/Flickr/CC BY 2.0
In the state of Western Australia sits the famous Wolfe Creek crater, the aftermath of a 14,000-tonne meteorite crashing into Earth thousands of years ago. A new study now claims the impact happened far more recently than we suspected, prompting a rethink on how often giant space rocks actually strike our planet.

A team of researchers from universities in Australia and the US took a close look at several features of the crater's underlying rock to get a precise measurement on the age of Wolfe Creek's most famous landmark.

Previous estimates have stated the crater could be 300,000 years old, but the new result places it much closer to our time, perhaps as little as 120,000 years ago. And knowing this is not just a geological curiosity, either.

As far as neat-looking craters go, they don't tend to be much bigger. With little rain to wear away the walls of the impact site, Wolfe Creek crater has been remarkably well preserved throughout the ages. But the site also stands out for the fact it is the second largest crater on Earth to still have fragments of the offending space rock.

There's no doubt the shrapnel of far bigger blasts exist out there somewhere, but with ocean and ice covering so much of our planet's surface, and wind and rain eating away at the geology, evidence is hard to come by.