Comets

The Tunguska explosion could have been caused by an asteroid that still orbits the Sun says new study

Brian Koberlein
Universe Today
Tue, 19 May 2020 19:04 UTC

On a cool Summer morning in 1908, a fireball appeared over Northern Siberia. Eyewitnesses described a column of blue light that moved across the sky, followed by a tremendous explosion. The explosion leveled trees across more than 2,000 square kilometers. The explosion is consistent with a large meteor strike, but to this day no evidence of a crater has been found. Now known as the Tunguska Event, its cause remains a mystery to this day.

One of the challenges in studying the Tunguska event is its remoteness. The region is sparsely populated, and the event only had a handful of witnesses. Scientific investigations of the event didn't occur until the 1920s. It was then that the impact region was mapped and early searches for an impact crater were undertaken. By the 1960s it was clear the event was similar to an airburst nuclear explosion, with an energy of about 5 Megatons.

Given what we know, the most likely cause is an airburst asteroid strike, where the asteroid explodes in the atmosphere, similar to the Chelyabinsk meteor strike in 2013. Given the size of the impact region, it's estimated that the original asteroid was nearly 70 meters across. This would explain why no large impact crater has been found.

But fragments of the Chelyabinsk were found soon after impact, and one would expect Tunguska fragments to have reached Earth. Despite several searches, nothing has been found. This has led some to look to other causes, such as a massive leak of natural gas, or even the explosion of an alien spacecraft. But a new study argues that there are no fragments because the asteroid didn't fragment after all. Instead, it glanced off Earth's atmosphere.

Asteroid NY65 - Another close call to occur in June

Sputnik News
Wed, 20 May 2020 18:54 UTC

NASA's Center for Near Earth Object Studies (CNEOs) is closely observing all asteroids approaching our planet within a distance of 0.05 astronomical units. In human terms, it may seem like nothing, but large space rocks can have a significant impact on Earth - even from a million-kilometres away.

The Apollo-class asteroid 441987, also dubbed 2010 NY65, will closely approach Earth on 24 June, according to NASA's tracking table.

The space rock is measured at between 140 and 310 metres, based on the way it reflects lights, and is estimated to be a small object in NASA's terms. However, it will approach our planet at a speed of 12.98 kilometre per second, coming as close as 0.02512 astronomical units to Earth.

New Comet P/2019 LM4 (Palomar)

Ernesto Guido
Remanzacco Blogspot
Fri, 15 May 2020 18:24 UTC

CBET 4775 & MPEC 2020-J68, issued on 2020, May 14, announce that an apparently asteroidal object discovered on images taken at Palomar on 2019 June 4 and 7 with the 1.2-m f/2.4 Schmidt telescope (and given the minor-planet designation 2019 LM_4 when published on MPS 1001527, along with observations made elsewhere on June 8) has been re-discovered showing cometary appearance at two other observatories. The new comet has been designated P/2019 LM4 (Palomar).

According to the CBET 4775: B. Li reported the discovery by G. Zhaori of an extended object on images taken by L. F. Hu with the 1.04-m f/1.8 Schmidt telescope at the XuYi Station of Purple Mountain Observatory on May 11 UT in the course of the "Chinese Near Earth Object Survey" (discovery observations tabulated below). Before the object was posted on the Minor Planet Center's NEOCP webpage, it wasdiscovered independently in images obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala on May 12, with Y. Ramanjooloo (University of Hawaii) reporting that the full-width-at-half-maximum size was 3".6 compared to 1".2 for nearby stars. Observations were subsequently identified at the Minor Planet of yet another apparent independent discovery of the comet from 2020 May 9.5 at mag 16.4-17.0 with a 0.5-m f/2 Schmidt reflector at Haleakala, Hawaii, in the course of the "Asteroid Terrestrial- Impact Last Alert System" (ATLAS) search program, though it appears that the ATLAS team did not report it as a comet.

New evidence reveals that giant meteorite impacts formed parts of the Moon's crust

Royal Ontario Museum
Mon, 11 May 2020 19:50 UTC

© Daniel D. Durda/FIAAA
An artist’s impression of how the early Moon was reshaped by an intense period of bombardment. A new study reveals that large impacts could have produced the range of lunar rocks sampled by the Apollo missions over 4.3 billion years ago.

Toronto, Canada - New research published today in the journal Nature Astronomy reveals a type of destructive event most often associated with disaster movies and dinosaur extinction may have also contributed to the formation of the Moon's surface.

A group of international scientists led by the Royal Ontario Museum has discovered that the formation of ancient rocks on the Moon may be directly linked to large-scale meteorite impacts.

The scientists conducted new research of a unique rock collected by NASA astronauts during the 1972 Apollo 17 mission to the Moon. They found it contains mineralogical evidence that it formed at incredibly high temperatures (in excess of 2300 °C/ 4300 °F) that can only be achieved by the melting of the outer layer of a planet in a large impact event. In the rock, the researchers discovered the former presence of cubic zirconia, a mineral phase often used as a substitute for diamond in jewellery.

The phase would only form in rocks heated to above 2300 °C, and though it has since reverted to a more stable phase (the mineral known as baddeleyite), the crystal retains distinctive evidence of a high-temperature structure. An interactive image of the complex crystal used in the study can be seen here using the .

New Comet C/2020 J1 (SONEAR)

Ernesto Guido & Adriano Valvasori
Remanzacco Blogspot
Thu, 07 May 2020 19:20 UTC

CBET 4769 & MPEC 2020-J37, issued on 2020, May 04, announce the discovery of a comet (magnitude ~17) on images taken with a 0.28-m f/2.2 astrograph of the "Southern Observatory for Near Earth Research" (SONEAR) at Oliveira, Brazil, on May 1 . The new comet has been designated C/2020 J1 (SONEAR).

We performed follow-up measurements of this object while it was still on the PCCP webpage.

Stacking of 8 unfiltered exposures, 90 seconds each, obtained remotely on 2020, May 04.3 from X02 (Telescope Live, Chile) through a 0.6-m f/6.5 astrograph + CCD, shows that this object is a comet with a compact coma about 5" in diameter.

Our confirmation image (click here for a bigger version)

New Comet C/2020 H6 (ATLAS)

Ernesto Guido & Adriano Valvasori
Remanzacco Blogspot
Tue, 05 May 2020 19:55 UTC

CBET 4768 & MPEC 2020-J23, issued on 2020, May 03, announce the discovery of a comet (magnitude ~18.5) on individual images from taken on Apr. 22 UT with a 0.5-m f/2 Schmidt reflector at Haleakala, Hawaii, in the course of the "Asteroid Terrestrial-Impact Last Alert System" (ATLAS) search program. The new comet has been designated C/2020 H6 (ATLAS).

We performed follow-up measurements of this object while it was still on the PCCP webpage.

Stacking of 10 unfiltered exposures, 120 seconds each, obtained remotely on 2020, April 28.4 from Q62 (iTelescope network) through a 0.50-m f/6.8 astrograph + CCD + focal reducer, shows that this object is a comet with a compact coma about 10" in diameter slightly elongated toward PA 330.

Our confirmation image (click on it for a bigger version)

Infectious disease modeling study casts doubt on the Justinianic Plague's impact

SESYNC
Fri, 01 May 2020 19:48 UTC

Annapolis, MD — Many have claimed the Justinianic Plague (c. 541-750 CE) killed half of the population of Roman Empire. Now, historical research and mathematical modeling challenge the death rate and severity of this first plague pandemic.

Researchers Lauren White, PhD and Lee Mordechai, PhD, of the University of Maryland's National Socio-Environmental Synthesis Center, examined the impacts of the Justinianic Plague with mathematical modeling. Using modern plague research as their basis, the two developed novel mathematical models to re-examine primary sources from the time of the Justinianic Plague outbreak. From the modeling, they found that it was unlikely that any transmission route of the plague would have had both the mortality rate and duration described in the primary sources. Their findings appear in a paper titled "Modeling the Justinianic Plague: Comparing hypothesized transmission routes" in PLOS ONE.

"This is the first time, to our knowledge, that a robust mathematical modeling approach has been used to investigate the Justinianic Plague," said lead author Lauren White, PhD, a quantitative disease ecologist and postdoctoral fellow at SESYNC. "Given that there is very little quantitative information in the primary sources for the Justinianic Plague, this was an exciting opportunity to think creatively about how we could combine present-day knowledge of plague's etiology with descriptions from the historical texts."

White and Mordechai focused their efforts on the city of Constantinople, capital of the Roman Empire, which had a comparatively well-described outbreak in 542 CE. Some primary sources claim plague killed up to 300,000 people in the city, which had a population of some 500,000 people at the time. Other sources suggest the plague killed half the empire's population. Until recently, many scholars accepted this image of mass death. By comparing bubonic, pneumonic, and combined transmission routes, the authors showed that no single transmission route precisely mimicked the outbreak dynamics described in these primary sources.

Burning object recorded in New Zealand sky likely a meteor

Hugh Collins
Otago Daily Times
Thu, 30 Apr 2020 21:29 UTC

© Matthew Willcox
Queenstown resident Matt Wilcox was lucky enough to witness what was probably a meteor on Wednesday evening.

A Queenstown man has captured some mysterious footage above the Remarkables mountain range.

Matt Wilcox was out for a walk when he spotted something odd.

"[It] was probably only visible for around a minute or so. Then it went behind the Remarkables and out of sight."

Southland Astronomical Society astronomer Mike Bailey had examined the footage and said he believed it was not a plane as it was moving too fast.

"It also looks dirty, aircraft contrails would normally be white," he added.

Prof. Wickramasinghe and team share potential origin and predict progression of COVID-19

EIN Press Wire
Tue, 28 Apr 2020 00:38 UTC

Scientific researchers released their findings about the source and predicted direction of the coronavirus and proposed critical measures for the pandemic.

London, UK, — Professor Chandra Wickramasinghe and his team of researchers believe that the novel coronavirus arrived on meteorites in Oct 2019 and instantaneously infected hundreds of thousands of people through the atmosphere, as meteorites were reported in China, Northern Italy, Michigan in October 2019. This is somewhat at odds with the mainstream assertion that it originated in bats in WUHAN, China. Given this disparity, they went to great lengths to produce a timely research paper to back up their argument.

In the research paper released on COVID-19, Professor Wickramasinghe puts forward several thought-provoking arguments. Notably that: "our informed view is that many people were almost simultaneously infected and naturally inoculated with the same COVID-19 virus strain."

New Comet C/2020 H2 (Pruyne)

Ernesto Guido, Marco Rocchetto & Adriano Valvasori
Remanzacco Blogspot
Wed, 29 Apr 2020 19:31 UTC

CBET 4761 & MPEC 2020-H220, issued on 2020, April 28, announce the discovery of a comet (magnitude ~16.5) by Theodore A. Pruyne on four 30-s CCD exposures taken with the Catalina Sky Survey's 0.68-m Schmidt telescope. The new comet has been designated C/2020 H2 (PRUYNE).

We performed follow-up measurements of this object while it was still on the PCCP webpage.

Stacking of 55 unfiltered exposures, 10 seconds each, obtained remotely on 2020, April 27.4 from X02 (Telescope Live, Chile) through a 0.6-m f/6.5 astrograph + CCD, shows that this object is a comet with a diffuse coma about 1' arcmin in diameter.

Our confirmation image (click on it for a bigger version)

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Psstoffgoy

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Comets

The Tunguska explosion could have been caused by an asteroid that still orbits the Sun says new study

Asteroid NY65 - Another close call to occur in June

New Comet P/2019 LM4 (Palomar)

New evidence reveals that giant meteorite impacts formed parts of the Moon's crust

New Comet C/2020 J1 (SONEAR)

New Comet C/2020 H6 (ATLAS)

Infectious disease modeling study casts doubt on the Justinianic Plague's impact

Burning object recorded in New Zealand sky likely a meteor

Prof. Wickramasinghe and team share potential origin and predict progression of COVID-19

New Comet C/2020 H2 (Pruyne)

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