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Tue, 29 Sep 2020
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Fireballs

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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.

Meteor

'Like a bomb!' Loud boom causes homes to shake in East Yorkshire, England

Mystery boom (stock)
© Globe Gazette
People reported feeling their houses shake and a loud noise over East Yorkshire on Thursday in what was thought to be a sonic boom.

Many living in the region took to social media to ask others if they had felt the earth moving and heard the sound that "reverberated" at around lunchtime on Thursday, May 14.

One man said: "Everything shook! Like a bomb!"

Another social media user said: "It felt like something had hit the house."

The strange activity was soon explained as a sonic boom - a very loud sound caused by shock waves created by any object that travels through the air faster than the speed of sound.

Comet 2

New Comet P/2019 LM4 (Palomar)

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.

Comet P/2019 LM4Palomar
© Remanzacco Blogspot

Fireball 2

Meteor fireball lights up sky over parts of southeast US

Southeast US meteor

The May 14, 2020, light in the sky can be seen in the upper left corner of this photo.
A fireball and bright flash were reported across portions of Florida, Georgia, and the Carolinas early Thursday morning.

A bright flash was seen by some in the Coastal Empire and Lowcountry around 12:45 a.m. The sight was even captured by some home security cameras.

Several reports were logged by the American Meteor Society. Fireballs, shootings stars, etc. are fairly common sights across the world. But, of course, it has to be pretty dark (and clear) to truly notice them.


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

Moon Impact
© 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 .

Fireball

Meteor fireball seen streaking across the sky in Natchez, Mississippi

FIREBALL
For one Natchez resident, a late-night trip out of his house turned into an otherworldly experience when he spotted a bright orange fireball streak across the sky.

"It scared the heck out of me," Alex Sandel said Monday morning. "It was bright orange, red and spinning."

Living near Merit Health Natchez, Sandel said he has stepped outside to watch a helicopter take off from the hospital's helipad Sunday evening at approximately 10:15 when he was startled by the fireball streaking across the sky.


Cassiopaea

Stargazer captures intriguing meteor fireball explosion over Oregon

Fireball over OR
© Wade Earl
An amateur stargazer was lucky enough to spot the exact moment a fireball hit the sky, discharging a fantastic bright aura. Wade Earl from Oregon captured a meteorite explosion during the Lyrid meteor shower.

The image, taken on April 21, 2020, was sent to the IMO (the International Meteor Organization) and AMS (the American Meteor Society) displays the meteor seemingly shattering twice as it reaches the atmosphere, meaning that Earl captured a double bursting fireball. In the image, we can spot the "W" of Cassiopeia lying to the lower right of the fireball.

Various space objects, such as comets or asteroids, produce a bright explosion of fore when they reach the sky. Air flows into cracks and pores of the rock, dragging apart and causing it to burst. Fireballs, on the other hand, are meteors that might be brighter than anything else ever seen.

Meteorite Explosion Lit Up the Sky over Oregon

Due to their speed at which they touch the Earth's atmosphere, fragments bigger than one millimeter can produce a bright light as they streak through the sky. These bright meteors are also dubbed fireballs, and they sometimes strike awe or fear for those who spot them.

Meteor

Woman spots 'ball of fire' streaking across sky over her garden in Liverpool, UK

Fireball over Liverpool
© Lottie Blake
A woman was startled to see a "ball of fire" streaking across the sky over her back garden.

Lottie Blake, 30, had just finished having dinner with her sister, yesterday evening, when she went into the kitchen to make a cup of tea.

However, as she was putting the kettle on she said she noticed something out of the window overlooking her back garden.

Lottie, from Whiston, told the Echo : "It was yesterday evening at about 8.00pm.

"We had just had our dinner so I went to the kitchen to make everyone a cuppa when I saw something out of the window.