Near-Earth objects and close calls

[miguel angel]

Hi all. I did not want to create a new thread so I will use this. My experience might be related to a 'Near-Earth objects and close calls' or maybe not.

Today, at about 12:45 p.m I was working at the office with my window open when I've suddenly heard a great explosion and felt a shake in the building and through my body. It's lasted a second. 4 more people heard and felt it at the office. I've looked outside but could not see anything that could give me any clue about what had happened. I looked at the sky, it was blue, without clouds or smoke. My vision from the building was about 160º left and right, I could not see if there was anything behind the building.

When I've arrived home, I've started to look for clues on the net about what could have happened. Nothing on the local or national digital papers. On FB, my wife's told me (I deleted my FB account years ago) a few people were commenting they had heard and felt the explosion even in 3 towns up to 20Km. far from where I was. One said she noted her house shook and her cat jumped & hid under the bed. Some others said it could be a military plane breaking the sound barrier. I have no experience as to say if you can feel what I've felt if that happens.

My gut feeling is that it could have been a meteoroid exploding above us, who knows.

I've been searching on twitter about explosions, meteors, meteoroids and I've not find anything of use BUT this:

https://twitter.com/x/status/1284048134902108161

I have no idea if this can be related but thought I should comment on this in case anybody else has experienced the same and can share his/her experience.

I attach a few images of my location and places where it has been reported on FB and one image with Ottawa which parallel looks similar to where I leave, according to Google Maps.

 

[Gary]

Meanwhile according to spaceweather.com Comet NEOWISE (C/2020 F3) is doing something usually reserved for Great Comets.

It has sprouted synchronic bands. Also known as "striae," these bands divide the comet's dust tail into linear regions of greater and lesser density.


"Comet NEOWISE is now in its full glory for northern hemisphere observers," says Cook. "This image is a stack of thirty 25s exposures at ISO1600. It clearly shows the formation of synchronic bands within the dust tail."

Synchronic bands have been seen in comet tails for centuries, yet only recently have astronomers begun to understand what they are. The turning point came in 2007 when European and NASA spacecraft observed the formation of striae in Comet McNaught (C/2006 P1). The process starts when a chunk of comet detaches itself from the nucleus. Boulder-sized chunks fragment into smaller and smaller pieces, a cascade shaped into long streamers by solar radiation pressure.


A few years ago, then-PhD student Ollie Price of University College London’s Mullard Space Science Laboratory was looking at old pictures of McNaught's striae and noticed some "weird goings-on." The bands were occasionally being bent and disrupted by some invisible force. "So I set out to investigate what might have happened to create this weird effect," he recalls.

Price and colleagues ultimately found the answer. The disruptions occured when Comet McNaught crossed the heliospheric current sheet (HCS)--a vast wavy structure in interplanetary space separating regions of opposite magnetic polarity. "It appears the dust may be electrically charged, and gets rearranged as it crosses the HCS boundary," says Karl Battams of the Naval Research Lab, a co-author of their 2018 paper.

Could the same thing happen to Comet NEOWISE? It's possible.

 

[Agron]

Meanwhile according to spaceweather.com Comet NEOWISE (C/2020 F3) is doing something usually reserved for Great Comets.

Acording to ancient astrologers and Trifon's reading this comet brings GOOD NEWS to humanity! PHEW

GOOD OMENS for the WORLD and All 12 SIGNS! Once in 6800 years!

 

[Laura]

I sure hope we can see it tonight. Last few nights have been seriously overcast.

 

[thorbiorn]

I sure hope we can see it tonight. Last few nights have been seriously overcast.

We tried to look for the comet and succeeded, but the core was not as bright at it appeared a few days ago when it was visible in the morning.

Below are some ideas for others who would like to try:
For maximum visibility Comet C/2020 F3 (NEOWISE) should be above the horizon and the twilight needs to be so reduced that the refracted rays of the Sun will not interfere too much. For an estimate of a good time, I checked the twilight calculator Twilight Calculator - Under mode, one can select: "Sunrise/Sunset + Twilight (Civil, Nautical & Astronomical)" pressed submit and then one can print out the times for a whole month as a pdf.

Just before attempting, I looked up the position of Neowise on Comets. Here is a screen shot:

The above map did not give the direction too clearly, but this one can get from Stellarium or from knowing that after sunset the Sun, during Summer will be somewhere in the northwest. It is better if there are few obstructions, like clouds, buildings or hills near the place of observation and in the direction one is searching.

The viewing condition at the moments are good, provided the sky is clear, because we are near the time of new moon. For a general moon calendar: Moon Phases 2020 – Lunar Calendar

The visible brightness of the comets is like for stars measured as the apparent magnitude. The following list is adapted from The astronomical magnitude scale The number is the apparent magnitude, followed by a description of what is needed to see the object, if this is not obvious, along with one or more examples:

-(minus)26
--(example)the sun
-13
--full moon
-6
--crescent moon
-4 naked eye: easy even from large cities;
--planet Venus
-2 naked eye;
--planet Jupiter
-1 naked eye;
--brightest star, Sirius; totally eclipsed moon, C/1995 O1 (Hale-Bopp) near peak
0 naked eye: difficult if near bright artificial lights but generally visible even from large cities;
--summer evening star Vega; C/1996 B2 (Hyakutake) at peak
+1 naked eye: brilliant as seen from dark, rural areas;
--planet Saturn
+2 naked eye: difficult but visible from small cities and suburbs; diffuse objects such as comets may require small binoculars from urban areas;
--stars of Big Dipper, Halley's comet in 1986 near peak
(plus is implied)3 naked eye: rural, suburban, small city
binoculars: bright, urban areas
--faintest naked-eye stars visible from many smaller cities/inner suburbs;
4 naked eye: (outer) suburbs
binoculars: cities (stars), suburban areas
faintest naked-eye (diffuse objects such as comets) stars visible from many smaller cities/(outer) suburbs
5 generally binocular objects from urban and suburban areas; faintest naked-eye stars visible from "dark" rural areas located some 40 miles (60 km) from major cities
--moons of Jupiter
6 binocular objects from suburban areas; faintest naked-eye stars visible from "dark" rural areas located some 100 miles (150 km) from major cities
--planet Uranus
7 binoculars; faintest naked-eye stars visible from "dark" rural areas located some 140 miles (200 km) from major cities and some 30 miles (50 km) from nearest town of population 5000 or so
--brightest minor planet (asteroid) and about 1-2 comets each year
8 binocular objects; from urban areas, such objects may only be visible with small telescopes
--planet Neptune
10 from dark sky, objects visible with 20x80 binoculars; from brighter sites, a larger telescope is needed
--at any given time, there are usually a couple of comets this bright.

The above list continues, but this ends what can be done with binoculars. At the moment the Neowise comet has a magnitude of 1.8 and it is waning, meaning the numbers will likely grow larger as time goes by. For comparison the next in line has a present magnitude of 7.9. As Neowise diminish in magnitude or the Moon shows up more brightly, one can try to compensate with binoculars which even now makes the view more impressive.

Happy watching, and who knows maybe while out there you will see something else too :)

 

[miguel angel]

My experience might be related to a 'Near-Earth objects and close calls' or maybe not.

I've been surfing the net searching for clues about what others & me could've experienced last Friday and the most plausible explanation to it probably was a sonic boom caused by a military plane breaking the sound barrier.

Sonic boom - Wikipedia

It seems other people worldwide are experiencing the same from time to time:

Boom sounds heard in Murrells Inlet, Litchfield area result of military aircraft training

https://twitter.com/x/status/1284080156013924352

Sorry for the noise in this thread.

 

[loreta]

I think it is interesting to see that many people are hearing this sonic booms, that means that military airplanes are doing many things up stairs, going there and there, also practicing maybe, or checking or preparing for something. It can be something to follow up because now that regular airplanes are almost prohibited, travels I mean, the air army surely have fun in the skies! they almost have their sky for them.

 

[Agron]

I've been surfing the net searching for clues about what others & me could've experienced last Friday and the most plausible explanation to it probably was a sonic boom caused by a military plane breaking the sound barrier.

Sonic boom - Wikipedia

It seems other people worldwide are experiencing the same from time to time:

Boom sounds heard in Murrells Inlet, Litchfield area result of military aircraft training

https://twitter.com/x/status/1284080156013924352

Sorry for the noise in this thread.

I believe it was last fall/early winter when Nato planes were demonstrating their power over Croatia with going over the speed of sound...

 

[Laurentien2]

some more this week,

Four massive asteroids en route to Earth, as scientists discover space rocks of INTERSTELLAR origin in our solar system

As NASA reports that five more asteroids are headed our way this week, four of which are over 50 meters in diameter, research from Brazil has identified some 19 space rocks of interstellar origin in our solar system.

www.rt.com

As NASA reports that five more asteroids are headed our way this week, four of which are over 50 meters in diameter, research from Brazil has identified some 19 space rocks of interstellar origin in our solar system.
Scientists at Sao Paulo State University’s Institute of Geosciences and Exact Sciences have identified asteroids formed in another solar system in the galaxy, and classified them as Centaurs.
These 19 ‘alien’ asteroids are located between the orbits of Jupiter and Neptune, and were spotted thanks to their unusual path around our solar system, according to one of the study’s lead authors, Maria Helena Moreira Morais.
As an example, Morais and her team highlighted asteroid 514107 Ka’epaoka’awela, which is Hawaiian for “mischievous opposite-moving companion of Jupiter.”


The space rock’s orbit corresponds to that of Jupiter, but it revolves around the sun in the opposite direction. The researchers then used a computer simulation they say “works like a time machine” tracing its trajectory backwards by 4.5 billion years to far beyond the edges of our solar system.

“When we identified it as an object that came from outside the solar system, we didn’t know whether it was an isolated case or part of a vast population of immigrant asteroids,” Morais said. “In this latest study, we recognized 19 Centaurs of interstellar origin.”

All planets and asteroids from our solar system come from a thin disk of gas and dust that once orbited the sun. When the disk broke up, everything expanded outwards along a plane, so any outsiders would likely have missed the memo and would therefore be relatively easy to spot, given their unusual orbits.

“Our simulation showed that, 4.5 billion years ago, these objects revolved around the sun in orbits perpendicular to the disk’s plane. In addition, they did so in a region distant from the gravitational effects of the original disk,” Morais said.

These kinds of studies examine “the importance of interstellar matter to the chemical enrichment of the solar system,” and might help us find new sources of elements that are running out here on Earth, such as helium.


Meanwhile, closer to home, the Earth will be buzzed by no fewer than five more local asteroids this week, ranging in diameter from a paltry 15 meters to a whopping 120 meters – or roughly twice the height of the Leaning Tower of Pisa.

Thankfully, all but one will pass us at a safe distance of between 3.3 million kilometers and 7.1 million kilometers. However, just to keep us on our toes, on Wednesday, a 15-meter asteroid will shoot past at a distance of around 782,000 kilometers.

I wonder if these centaurs are not directed or pulled by something else.

 

[thorbiorn]

The last few nights I have been out observing the Neowise comet and it is waning. Theskylive.com has

Comet C/2020 F3 (NEOWISE) latest observed magnitude is 2.0 and it is in the constellation of Ursa Major. It should be visible to the naked eye under dark skyes, might require a small binocular from light polluted areas.

If one knows where the comet is, one can find it even if it not completely dark and even if the tail can not yet be seen, but then it just looks like another star, so nothing special except that it appears where there is no star or planet listed on the maps. Last night there was more mist and traces of clouds in the local skies and this plus a waning comet made it less spectacular.

Here is an image that shows the present location of the comet in the solar system.

The other night we saw a bright meteor, and we have since been discussing what meteor stream it may belong to:
One candidate was the Perseids:

The Perseids are a prolific meteor shower associated with the comet Swift–Tuttle. The meteors are called the Perseids because the point from which they appear to hail (called the radiant) lies in the constellation Perseus

It is a bit sobering to consider that some of the meteor showers we watch were comets and to wonder about the processes that led to the disintegration of these comets.

On this page one, can get a 3D presentation of the flow of the Perseid shower. It is possible to tilt the plane, if one holds down the left click part of the mouse. One can also choose different perspectives. Below is a Solar System perspective. The orbit of the Earth is located somewhere along the blue-green segment near the Sun which also is "the eye" of the movement of the meteor stream. The flow of the meteors of the stream across the orbit of the Earth is always there, we just don't see it.

 

[thorbiorn]

If the composition of near earth objects reflects that of meteorites, then most are stony or chondrite meteorites. Among these one group is rich in carbon.

Carbonaceous chondrite - Wikipedia

en.wikipedia.org

Carbonaceous chondrites or C chondrites are a class of chondritic meteorites comprising at least 8 known groups and many ungrouped meteorites. They include some of the most primitive known meteorites. The C chondrites represent only a small proportion (4.6%)[1] of meteorite falls.

Some famous carbonaceous chondrites are: Allende, Murchison, Orgueil, Ivuna, Murray, Tagish Lake, and Sutter's Mill.

The carbonaceous chondrites have been objects of intense study because they contain much carbon which is essential to organic lifeforms. For instance, the Wiki about the meteorite called Orgueil says:

It fell on May 14, 1864, a few minutes after 20:00 local time, near Orgueil in southern France. About 20 stones fell over an area of 5-10 square kilometres. A specimen of the meteorite was analyzed that same year by François Stanislaus Clöez, professor of chemistry at the Musée d'Histoire Naturelle, who focused on the organic matter found in this meteorite. He wrote that it contained carbon, hydrogen, and oxygen, and its composition was very similar to peat from the Somme valley or to the lignite of Ringkohl near Kassel. An intense scientific discussion ensued, continuing into the 1870s, as to whether the organic matter might have a biological origin.[2]

A large piece is kept at the Museum of Natural History in the city of Montauban, though it does not appear prominently if at all on their homepage. However one shop that prepares cakes and sweets has used the story about the meteorite that fell near Montauban in their advertisement for a product they sell:

It is an interesting question if some types of the near-earth objects are more likely to be carriers of lifeforms or factors that can affect life on the biological level.

 

[Color]

Couldn't understand what I was looking at exactly until I read the capture.

https://twitter.com/x/status/1286053695956881409

 

[Agron]

NLC and Comet Neowise over Zillertaler Alps

Comet Neowise above Montafon, seen from Kirchlispitze, Rätikon

 

[Color]

Quite amazing
"The Comet Neowise with a shooting star going right through it, leaving behind a cloud of smoke. Captured over southern France on Wednesday." Photo by Antoine Mangiavacca
.

 

[Laurentien2]

they keep coming.

FOUR asteroids to shoot past Earth in ONE DAY, after astronaut warns there are 1 MILLION out there that can hit us

As the week begins with a flurry of asteroidal activity, with four space rocks set to shoot past Earth on Tuesday alone, two Indian teenagers have discovered yet another space rock due to cross paths with our planet.

www.rt.com

As the week begins with a flurry of asteroidal activity, with four space rocks set to shoot past Earth on Tuesday alone, two Indian teenagers have discovered yet another space rock due to cross paths with our planet.
To kick things off, the small-house-sized asteroid 2020 OO1 will buzz by at a distance of 669,000km on July 27.
Then on Tuesday, we will witness a whopping four flybys in one day, starting with the relatively safe and short-lived sojourns of 2020NZ amd 2020 OE2, 28m and 12m in diameter respectively, which will blow through our cosmic backyard at a safe distance of 3.1 million kilometers and 1.7 million kilometers.


Next, the real fun begins with the car-sized (2.9m) 2020 OY4, set to skip by at a distance of just 41,500km. It will be followed by the plane-sized (26m) 2020 OR4, which will pass us at 10 times that distance, looping beyond Earth at 457,000km.

Both of these might be considered a little too close for comfort, as the distance between Earth and the Moon is just 384,400km. Neither pose any real threat, however, as they are unlikely to strike us and even if they did, they would be no match for our planet’s atmosphere.

The brief barrage of space rocks is reason enough to set suspicious stargazers on edge, especially after two 14-year-old girls in India, Vaidehi Vekariya and Radhika Lakhani, discovered asteroid HLV2514 which will also, one day, cross paths with Earth.

The teen stargazers spotted the space rock during the All India Asteroid Search Campaign (AIASC), part of IASC, an outreach program run by NASA.

“It is, in fact, a near-Earth object (NEO),” IASC Director Patrick Miller confirmed, adding that it will evolve into an Earth-crossing asteroid at some undetermined point in the future.

For the moment at least, it appears our planetary defenses are operating optimally as they spotted the outbound Chinese probe Tianwen-1 en route to Mars shortly after beginning its seven-month journey to the Red Planet while scanning the sky for wayward asteroids.

The surreptitious snap will come as little relief, however, as European Space Agency (ESA) astronaut Paolo Nespoli, who was a mission specialist aboard the Space Shuttle Discovery in 2007, warned that there are more than one million asteroids that could hit Earth.


Formerly the agency’s oldest active astronaut prior to his retirement in 2018 at age of 61, Nespoli posted a video of asteroid 163348 (2002 NN4), which passed 3.2 million miles by Earth, with a rather ominous caption to mark World Asteroid Day on June 30.

“Between small and big, there are more than one million asteroids out there that could hit the Earth,” he said. “Right now, we are mostly ignoring the probability of a massive one suddenly appearing. It’s time to act: #AsteroidDay.”