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Fri, 27 Nov 2020
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Question

India's Lake Lonar turns pink baffling scientists and locals

Maharashtra's Lonar Lake has turned pink overnight, leaving scientists and locals baffled about the reasons behind this change. Located in the Buldana district about 500 km from Mumbai, the Lonar crater had formed due to a meteorite, which hit the earth about 50,000 years ago.
Lonar Lake, India
© Outlook India
Water in the Lonar Lake, which has now turned Pink
This is the world's third-largest crater formed due to a meteorite strike. People in the area were considerably surprised when the lake's normal bluish-green water turned a pinkish red.

Comet 2

New Comet C/2020 K7 (PANSTARRS)

CBET 4790 & MPEC 2020-L09, issued on 2020, June 02, announce the discovery of a comet (magnitude ~20) in four 45-s w-band CCD images obtained with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala. The new comet has been designated C/2020 K7 (PANSTARRS).

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

Stacking of 8 unfiltered exposures, 180 seconds each, obtained remotely on 2020, June 02.2 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 6" in diameter and a tail 3" long in PA 306 (Observers E. Guido, M. Rocchetto, E. Bryssinck, M. Fulle, G. Milani, C. Nassef, G. Savini).

Our confirmation image (click here for a bigger version)

Comet C/2020 K7
© Remanzacco Blogspot

Fireball 3

Ancient accounts of 'Death from Above'

Meteorite Barage
© John Martin/Wikimedia Commons
Evidence suggests that a devastating barrage of meteorites rained down on the Dead Sea city of Tall el-Hammam in what is now Jordan. And, according to some researchers who think Tall el-Hammam was the biblical city of Sodom, that scenario could explain its destruction.
When we stargaze, we bask in photons that have traveled for many millennia before reaching our eyes. To us, the stars appear fixed on a so-called celestial sphere that encapsulates our entire earthly existence.

The truth, of course, is that no such sphere exists. Instead, stars and galaxies are scattered through the cosmos at distances so great they're incomprehensible to us.

But not all celestial phenomena exist so far away. Every day, shooting stars fail to recognize a boundary between space and Earth, dropping rocks from above — and often with dramatic results.

Our planet is vast, so meteorites typically don't concern us. But every once in a while, these objects actually strike humans and our property. Based purely on statistics, researchers estimate that a space rock should strike a human roughly once every nine years. And with those odds, you'd expect people to get killed by meteorites fairly often.

"I do strongly suspect that stats on 'death by asteroid' have been severely undercounted through human history," NASA Planetary Defense Officer Lindley Johnson told Astronomy via email. "It's only been in the last half century or so that we've even realized that such a thing could happen."

However, researchers still have not found a single confirmed case of death by space rock. But that's not to say we haven't come close. Modern history is full of near misses. On many occasions, space rocks have exploded over populated areas and sent thousands of meteorites raining down.

One of the most recent and well-known examples occurred in Chelyabinsk, Russia, in 2013, when a house-sized asteroid exploded over the city and injured some 1,200 people. Further back, on Jan. 30, 1868, a meteor exploded outside a town called Pultusk, near Warsaw, Poland, creating a literal meteor shower: More than 100,000 stones fell from the sky. The biggest recovered meteorite (a fragment of a space rock that makes it to the ground) weighed 20 pounds. It's the largest meteorite fall on record.

Fireball 5

Meteor fireball caught on camera over Armenia

Meteor Fireball
© CCO
Videos of the suspected meteor's fall appear to suggest that it went down somewhere in the vicinity of the Armenian town of Hrazdan.

Residents of Armenia's Kotyak province were likely in for quite a surprise on the evening of 27 May as a flying object, which Public Radio of Armenia suggests might've been a meteor, flashed across the sky.

According to the media outlet, videos of this event that started emerging online show the object falling in the vicinity of the town of Hrazdan which is located about 45 kilometers northeast of the capital Yerevan.

Question

Residents in New Zealand report mystery fireball 'crashing' into river

Waipuna bridge
© BBR Contech
Waipuna bridge: did a meteorite crash land into the Tamaki River?
Several Pakuranga residents reported seeing a bright flash of light or a "fireball" above the Tamaki River in the vicinity of Waipuna Bridge at around 6:47 pm on Monday 25 May. According to some eyewitnesses, the object was alleged to have then crashed into the water.

Reports of a "bright light" and "an explosion" flooded the east Auckland grapevine page as local people recounted what they had seen. Many speculated a meteor, a rocket from nearby Rocket Lab, or even a flare was responsible.

Corinne Hill, whose property on Pakuranga Rd backs on to the river saw "A Bright orange-red (object) about the size of 3 full moons joined together. It (sic) was travelling at speed over the water till it appeared to hit the water and disappeared."

According to Hill, the object made no sound, and by the time she "went to get binoculars out" it had gone.

Ms Hill also stated the object "It appeared to grow in size as it travelled, so my initial thought was it looked like a ball of fire but then I got wondering what it was. There were cars on the bridge at the time commuting, so I was thinking one of them may have also seen it."

Police, The Civil Aviation Authority (CAA), and Stardome observatory were approached for comment.

Info

Chicxulub simulations reveal trajectory of impact

Chicxulub Crater
© Gareth Collins/Imperial College London
Asymmetries of the Chicxulub crater.
The asteroid that most believe wiped out the dinosaurs struck at the deadliest possible angle, according to new analysis combining 3D numerical impact simulations and geophysical data from the site.

The 66-million-year-old Chicxulub crater in Mexico was formed by a steeply inclined impact of between 45 and 60 degrees to the horizontal, the researchers suggest, which maximised the amount of climate-changing gases thrust into the upper atmosphere.

Such a strike likely unleashed billions of tonnes of sulphur, blocking the Sun and triggering the nuclear winter that killed 75% of life on Earth.

The researchers - from Imperial College London (ICL), the University of Freiburg, Germany, and the University of Texas, US - say their models are the first fully 3D simulations to reproduce the whole dramatic event, from the initial impact to the crater formation.

Reproducing the final stage, in which the transient crater collapsed to form the final structure, allowed them to make the first comparison between 3D simulations and the present-day structure of the crater.

"Our simulations provide compelling evidence that the asteroid struck at a steep angle, perhaps 60 degrees above the horizon, and approached its target from the northeast," says ICL's Gareth Collins, lead author of a paper in the journal Nature Communications.

Comet 2

New Comet C/2020 K3 (Leonard)

CBET 4782 & MPEC 2020-K159, issued on 2020, May 25, announce the discovery of a comet (magnitude ~18) by G. J. Leonard on images taken on May 22 UT with the Catalina Sky Survey's 0.68-m Schmidt reflector. The new comet has been designated C/2020 K3 (Leonard).

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

Stacking of 20 unfiltered exposures, 55 seconds each, obtained remotely on 2020, May 23.4 from H06 (iTelescope network) through a 0.50-m f/6.8 reflector + CCD + f/4.5 focal reducer, shows that this object is a comet with a diffuse irregular coma about 15" in diameter

Our confirmation image (click here for a bigger version)
C/2020 K3 Leonard
© Remanzacco Blogspot

Info

Active object in Jupiter's orbit is first of its kind seen by astronomers

asteroid 2019LD2
© JD Armstrong/IfA/LCOGT
Image of asteroid 2019LD2 taken on June 11th, 2019, using the Las Cumbres Observatory Global Telescope (LCOGT) NetworkÊ »s 1.0-meter telescope at Cerro Tololo, Chile.
We often think of asteroids and comets as distinct types of small bodies, but astronomers have discovered an increasing number of "crossovers." These objects initially appear to be asteroids, and later develop activity, such as tails, that are typical of comets.

Now, the University of Hawaiʻi's Asteroid Terrestrial-impact Last Alert System (ATLAS) has discovered the first known Jupiter Trojan asteroid to have sprouted a comet-like tail. ATLAS is a NASA-funded project using wide-field telescopes to rapidly scan the sky for asteroids that might pose an impact threat to Earth. But by searching most of the sky every two nights, ATLAS often finds other kinds of objects - objects that aren't dangerous, but are very interesting.

Early in June 2019, ATLAS reported what seemed to be a faint asteroid near the orbit of Jupiter. The Minor Planet Center designated the new discovery as 2019 LD2. Inspection of ATLAS images taken on June 10 by collaborators Alan Fitzsimmons and David Young at Queen's University Belfast revealed its probable cometary nature. Follow-up observations by the University of Hawaiʻi's J.D. Armstrong and his student Sidney Moss on June 11 and 13 using the Las Cumbres Observatory (LCO) global telescope network confirmed the cometary nature of this body.

Later, in July 2019, new ATLAS images caught 2019 LD2 again - now truly looking like a comet, with a faint tail made of dust or gas. The asteroid passed behind the Sun and was not observable from the Earth in late 2019 and early 2020, but upon its reappearance in the night sky in April of 2020, routine ATLAS observations confirmed that it still looks like a comet. These observations showed that 2019 LD2 has probably been continuously active for almost a year.

Fireball 2

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

Tunguska Airburst
© Universe Today
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.
Tunguska Fallen Trees
© Leonid Kulik expedition
Photograph of fallen trees seen by a 1929 expedition to the region.
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.

Fireball 5

Asteroid NY65 - Another close call to occur in June

Asteroid heading to Earth
© CCO
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.