Most or nearly all impact craters in the solar system are round.
The accepted explanation is not believable.
This observation is also interesting from the Electric Universe perspective.
This post is long with details.
The observation of round craters includes the Moon (both sides), Mars, Mercury, Vesta, and several moons. Even Pluto has 'halo' craters.
It is very suspicious they are always round given anyone would naturally assume random impact angles would result in a variety of shapes. There is consistency, not randomness; that must be explained.
Barrington Crater in Arizona, being rather round had been assumed to be an impact crater. Upon investigation no meteor was found. That discovery required an ad hoc explanation that was not logical.
Here are two references for the standard explanation:
1) from Scientific American
"When geologists and astronomers first recognized that lunar and terrestrial craters were produced by impacts, they surmised that much of the impacting body might be found still buried beneath the surface of the crater floor. (Much wasted effort was expended to locate a huge, buried nickel-iron meteorite believed to rest under the famous Barringer meteor crater near Winslow, Ariz.) Much later, however, scientists realized that at typical solar system velocities--several to tens of kilometers per second--any impacting body must be completely vaporized when it hits.
"At the moment an asteroid collides with a planet, there is an explosive release of the asteroid's huge kinetic energy. The energy is very abruptly deposited at what amounts to a single point in the planet's crust. This sudden, focused release resembles more than anything else the detonation of an extremely powerful bomb. As in the case of a bomb explosion, the shape of the resulting crater is round: ejecta is thrown equally in all directions regardless of the direction from which the bomb may have arrived.
"This behavior may seem at odds with our daily experience of throwing rocks into a sandbox or mud, because in those cases the shape and size of the 'crater' is dominated by the physical dimensions of the rigid impactor. In the case of astronomical impacts, though, the physical shape and direction of approach of the meteorite is insignificant compared with the tremendous kinetic energy that it carries.
"An exception to this rule occurs only if the impact occurs at an extremely shallow, grazing angle. If the angle of impact is quite close to horizontal, the bottom, middle and top parts of the impacting asteroid will strike the surface at separate points spread out along a line. In this case, instead of the energy being deposited at a point, it will be released in an elongated zone--as if our 'bomb' had the shape of a long rod.
"Hence, a crater will end up having an elongated or elliptical appearance only if the angle of impact is so shallow that different parts of the impactor strike the surface over a range of distances that is appreciable in comparison with the final size of the crater as a whole. Because the final crater may be as much as 100 times greater than the diameter of the impactor, this requires an impact at an angle of no more than a few degrees from horizontal. For this reason, the vast majority of impacts produce round or nearly round craters, just as is observed.
2) from scienceabc:
When a meteor hits the lunar surface, a shockwave spreads out in all directions and the impact creates a dent in the surface that is much bigger than the size of the impacting object itself. Since the impact sprays ejecta in all directions in equal proportions (just like the shockwave of an explosion), the direction and incident angle of the impact become irrelevant in determining the shape of the crater.
I suggest more than just 'the vast majority of craters' are round. When looking at those with a very small diameter they are nearly 100% and these are the most frequent.
I totally agree with the observation: ' this may seem at odds with our daily experience of throwing rocks.'
When I throw a flat rock as fast as I can (for maximum kinetic energy) to get as many skips at possible on a lake,
I will NEVER see a big splash at the moment of each touch, on each skip.
The kinetic energy must be transferred from the moving body when the velocity stops because the energy in the momentum must be conserved.
It makes no sense to propose an explosion to cause the stop in the motion, thereby vaporizing the object and leaving a round hole in the surface at the moment of a touch, regardless of approach angle.
This proposal, though widely accepted (as shown by the same story repeated in different sources), is absolutely not believable.
The asteroid must stop for it to explode, when dispersing that kinetic energy. It will not stop at a shallow angle so there can be no explosion.
Also an asteroid cannot create the substantial energy for its own explosion as that violates thermodynamics.
I was not aware of this strange consensus explanation for craters until recently.
Also, there have been events that do not conform with the expectation an explosion of a meteor causes a crater.
1) Barrington Crater, as noted above, contains no meteor.
2) Tunguska event had no crater.
The Tunguska event was a large explosion that occurred near the Stony Tunguska River on the morning of 30 June 1908.The explosion over the sparsely populated Eastern Siberian Taiga flattened 2,000 square kilometres (770 square miles) of forest, yet caused no known human casualties. The explosion is generally attributed to the air burst of a meteor. It is classified as an impact event, even though no impact crater has been found; the object is thought to have disintegrated at an altitude of 5 to 10 kilometres (3 to 6 miles) rather than to have hit the surface of the Earth.
3) Shoemaker Levy 9 broke up into fragments far from Jupiter.
4) Chelyabinsk meteor explosion had no crater though it was high above the surface.
The Chelyabinsk meteor was a superbolide that entered Earth's atmosphere over Russia on 15 February 2013. It was caused by an approximately 20 m (66 ft) near-Earth asteroid with a speed of 19.16 ± 0.15 kilometres per second (60,000–69,000 km/h or 40,000 – 42,900 mph). It quickly became a brilliant superbolide meteor over the southern Ural region. The light from the meteor was brighter than the Sun, visible up to 100 km (62 mi) away. It was observed over a wide area of the region and in neighbouring republics. Some eyewitnesses also felt intense heat from the fireball.
Due to its high velocity and shallow angle of atmospheric entry, the object exploded in an air burst over Chelyabinsk Oblast, at a height of around 29.7 km (18.5 mi; 97,000 ft). The explosion generated a bright flash, producing a hot cloud of dust and gas that penetrated to 26.2 km (16.3 mi), and many surviving small fragmentary meteorites, as well as a large shock wave. The bulk of the object's energy was absorbed by the atmosphere, with a total kinetic energy before atmospheric impact estimated from infrasound and seismic measurements to be equivalent to the blast yield of 400–500 kilotons of TNT (about 1.4–1.8 PJ) range – 26 to 33 times as much energy as that released from the atomic bomb detonated at Hiroshima.
Here is the NASA interpretation posted in 2019 of Tycho, a well known crater .
Tycho Crater is an one of the most prominent craters on the moon. It appears as a bright spot in the southern highlands with rays of bright material that stretch across much of the nearside. Its prominence is not due to its size: at 85 km in diameter, it's just one among thousands of this size or larger. What really makes Tycho stand out is its relative youth. It formed recently enough that its beautiful rays, material ejected during the impact event, are still visible as bright streaks. All craters start out looking like this after they form, but their rays gradually fade away as they sit on the surface, exposed to the space environment which over time darkens them until they fade into the background.
From a different NASA article (also 2019):
Tycho's central peak is thought to be material that has rebounded back up after being compressed in the impact, and though it's a peak now, it originated at greater depth than any other portion of the crater. The floor of the crater is covered in impact melt, rocks that were heated to such high temperatures during the impact event that they turned to liquid, and flowed across the floor. Impact melt flowed downhill and pooled, where it cooled.
I find this story interesting because Tycho is round but it is described as an impact not an explosion, unlike the common explanation for round craters, noted above. Material is compressed and rebounds, and is not exploded away.
Those bright rays are not ejected material (substantial rubble is not visible anyway) but are surface electrical scarring.
The electrical, non-impact explanation for round craters was first (AFAIK) proposed by Ralph Juergens in the academic journal Pensee in 1974. An excerpt can be found on line.
This post includes new references and observations after 1974. Many probes have visited all the planets and many of their moons since 1974. The Hubble Telescope was deployed in 1990.
This topic followed a review of the photographs and data available for several planets and moons. Any omissions are my mistake but the observations are consistent.
Tycho is a near perfect example of a Lichtenberg figure.
Lichtenberg figures are branching electric discharges that sometimes appear on the surface or in the interior of insulating materials. Lichtenberg figures are often associated with the progressive deterioration of high voltage components and equipment. The study of planar Lichtenberg figures along insulating surfaces and 3D electrical trees within insulating materials often provides engineers with valuable insights for improving the long-term reliability of high voltage equipment. Lichtenberg figures are now known to occur on or within solids, liquids, and gases during electrical breakdown.
Rayed craters are created by a very high voltage discharge to the surface, resulting in the Lichtenberg figure.
This is like electric discharge machining (EDM).
When the current is high enough a birkelund current pair of filaments can form a helix. As the helix rotates it machines the bottom surface of the crater floor but sometimes leaves a peak at the center between the two filaments. The outside of the filament rotation machines the round crater rim while maintaining the diameter. This machining process will result in a flat floor
This perpendicular electrical process explains the convex floor of Mimas.
For the multitude of small round craters observed in so many places the electrical discharge was brief, like a lightning bolt but always perpendicular. No ejected material is ever observed beyond the sharp circular rim around these craters. Material was vaporized into dust, not ejected as boulders. Apollo astronauts certainly encountered dust. The moon has no atmosphere for erosion.
EDM process can sometimes cause sputtering which are observed as many small shallow craters. These are also seen on the Moon.
Linear crater chains (consecutive duplicate craters in a line with slight overlap) are observed in several places like the Davy crater chain on the Moon and Enki Catena on Ganymede.
The Moon has several 'walled plains' or very wide round craters with a flat floor.
When a substantial electric discharge stops, sometimes a follow up discharge occurs almost immediately. Like with lightning it targets the highest point. This explains an observed combination of one larger crater that has a much smaller very round crater located precisely on the rim's highest point. For these crater pairs to arise from random impacts is an incredible coincidence. Examples of this 'rim shot' on the Moon are the Adams, Taruntius and Schikard craters.
Proposing so many impacts at random angles will always form a round crater everywhere is rather unbelievable.
However there are some craters observed in our solar system, round or not, that are very difficult for a proposed impact.
Mimas, orbiting Saturn, has the Herschel crater whose diameter is 1/3 of the moon. On the scale of Earth that would be Canada.
Rather than being deep for such a diameter, the floor appears to be somewhat convex. There is a central peak though not tall. The rim appears almost like a hexagon (6 rough segments).
This crater with its combination of floor, rim, and size is an unlikely impact.
The minor planet Vesta has Rheasilvia crater with a diameter at 90% of Vesta.
Phobos, orbiting Mars, has the Stickney crater, whose diameter is about 9km in diameter vs the moon's diameter of about 20km. For a crater to be half the size of the moon and not break the moon on impact seems unlikely. There are no visible fractures around this crater, from an impact.
However the LLNL found a way 'in a 3D simulation' the moon Phobos would not break during an impact.
From a 2016 research paper in the Geophysical Review Letters:
"We've demonstrated that you can create this crater without destroying the moon if you use the proper porosity and resolution in a 3D simulation," said Megan Bruck Syal, an author on the paper and member of the LLNL planetary defense team. "There aren't many places with the computational resources to accomplish the resolution study we conducted."
Alternately, the crater is not from an impact.
There are other craters like Tycho.
Langrenus on the Moon has a larger diameter, at 132km, than Tycho.
Debussy, a rayed crater on Mercury, also looks like Tycho and both are 85 km.
Grattieri, a rayed crater on Mars looks the same as Tycho, but is just 32 km vs 85 km.
Of course the nebular hypothesis for the formation of the solar system must deal with craters. This is how:
The Late Heavy Bombardment (abbreviated LHB and also known as the lunar cataclysm) is an event thought to have occurred approximately 4.1 to 3.8 billion years ago (Ga), at a time corresponding to the Neohadean and Eoarchean eras on Earth. During this interval, a disproportionately large number of asteroids are theorized to have collided with the early terrestrial planets in the inner Solar System, including Mercury, Venus, Earth, and Mars.
The Late Heavy Bombardment happened after the Earth and other rocky planets had formed and accreted most of their mass, but still quite early in Earth's history.
Evidence for the LHB derives from lunar samples brought back by the Apollo astronauts. Isotopic dating of Moon rocks implies that most impact melts occurred in a rather narrow interval of time. Several hypotheses attempt to explain the apparent spike in the flux of impactors (i.e. asteroids and comets) in the inner Solar System, but no consensus yet exists. The Nice model, popular among planetary scientists, postulates that the giant planets underwent orbital migration and in doing so, scattered objects in the asteroid and/or Kuiper belts into eccentric orbits, and into the path of the terrestrial planets. Other researchers argue that the lunar sample data do not require a cataclysmic cratering event near 3.9 Ga, and that the apparent clustering of impact-melt ages near this time is an artifact of sampling materials retrieved from a single large impact basin. They also note that the rate of impact cratering could differ significantly between the outer and inner zones of the Solar System.
I was suprised to discover the distribution of craters.
Wikipedia has a "List of craters in the Solar System"
As of 2017, there is a total of 5,223 craters on 40 astronomical bodies, which includes minor planets (asteroids and dwarf planets), planets, and natural satellites
A surprise for me in this list is the distribution. Moon has 1624, Mars has 1092, Venus has 900, Mercury has 397, Earth 190, Callisto had 131, Ganymede has 131;Titan has 11, Triton has 9; there are others in the list.
Ganymede is similar in size to Titan but Titan has a thick atmosphere and it has fewer craters; those could be related.
Venus has a very thick atmosphere while Mars has a thin one.
I would expect Venus having such a dense atmosphere would burn up or slow down most meteors to result in fewer significant impacts; it has many, almost the same as Mars.
Decreasing sizes: Earth, Venus, Mars, Ganymede, Titan, Mercury, Callisto, Io, Moon, Europa, Triton.
Moon has the most craters but is smaller than most of the bodies in the list.
Mercury is the same size as Callisto; both are smaller than Ganymede.
Mercury is much closer to the Sun which I might expect could attract wayward meteors.
Mercury has more craters than larger bodies.
Of course these craters are random regardless of the mechanism.
However the distribution is interesting.
I just offer the distribution of the numbers to those who are curious.
I will not make unjustified conclusions about possible meteor behaviors.
I was surprised cosmologists have proposed migrating planets.
Noted in the quote above:
The Nice model, popular among planetary scientists, postulates that the giant planets underwent orbital migration.
This is proposed to explain the disarray during the meteor bombardment period.
From the Electric Universe perspective those migrating planets can provide the source for the observed craters created by electric discharge events.
Both Jupiter and Saturn are assumed to have substantial mass in condensed matter as liquid metallic hydrogen.
Jupiter is thought to consist of a dense core with a mixture of elements, a surrounding layer of liquid metallic hydrogen with some helium, and an outer layer predominantly of molecular hydrogen. Beyond this basic outline, there is still considerable uncertainty. The core is often described as rocky, but its detailed composition is unknown, as are the properties of materials at the temperatures and pressures of those depths (see below). In 1997, the existence of the core was suggested by gravitational measurements, indicating a mass of from 12 to 45 times that of Earth, or roughly 4%–14% of the total mass of Jupiter. The presence of a core during at least part of Jupiter's history is suggested by models of planetary formation that require the formation of a rocky or icy core massive enough to collect its bulk of hydrogen and helium from the protosolar nebula. Assuming it did exist, it may have shrunk as convection currents of hot liquid metallic hydrogen mixed with the molten core and carried its contents to higher levels in the planetary interior. A core may now be entirely absent, as gravitational measurements are not yet precise enough to rule that possibility out entirely.
The core region may be surrounded by dense metallic hydrogen, which extends outward to about 78% of the radius of the planet. Rain-like droplets of helium and neon precipitate downward through this layer, depleting the abundance of these elements in the upper atmosphere.
from a NASA source:
As Jupiter rotates, it takes its magnetic field around with it, sweeping past Io and stripping off about 1 ton (1,000 kilograms) of Io's material every second. This material becomes ionized in the magnetic field and forms a doughnut-shaped cloud of intense radiation referred to as a plasma torus. Some of the ions are pulled into Jupiter's atmosphere along the magnetic lines of force and create auroras in the planet's upper atmosphere. It is the ions escaping from this torus that inflate Jupiter's magnetosphere to over twice the size we would expect.
'Despite consisting mostly of hydrogen and helium, most of Saturn's mass is not in the gas phase, because hydrogen becomes a non-ideal liquid when the density is above 0.01 g/cm3, which is reached at a radius containing 99.9% of Saturn's mass. The temperature, pressure, and density inside Saturn all rise steadily toward the core, which causes hydrogen to be a metal in the deeper layers.
Standard planetary models suggest that the interior of Saturn is similar to that of Jupiter, having a small rocky core surrounded by hydrogen and helium with trace amounts of various volatiles.This core is similar in composition to Earth, but more dense. Examination of Saturn's gravitational moment, in combination with physical models of the interior, has allowed constraints to be placed on the mass of Saturn's core. In 2004, scientists estimated that the core must be 9–22 times the mass of Earth, which corresponds to a diameter of about 25,000 km. This is surrounded by a thicker liquid metallic hydrogen layer, followed by a liquid layer of helium-saturated molecular hydrogen that gradually transitions to a gas with increasing altitude. The outermost layer spans 1,000 km and consists of gas.
from a NASA source:
In 2008, Cassini detected a beam of energetic protons near Enceladus aligned with the magnetic field and field-aligned electron beams. A team of scientists analyzed the data and concluded the electron beams had sufficient energy flux to generate a detectable level of auroral emission at Saturn. A few weeks later, Cassini captured images of an auroral footprint in Saturn's northern hemisphere. In 2009, a group of Cassini scientists led by Donald Gurnett at the University of Iowa in Iowa City, detected more complementary signals near Enceladus consistent with currents that travel from the moon to the top of Saturn's atmosphere, including a hiss-like sound from the magnetic connection. That paper was published in March in Geophysical Research Letters.
Both Jupiter and Saturn are active electrically.
If either came near other bodies in the solar system one could expect an electric discharge due to a charge differential. These very large planets would probably supply a very large differential. I also expect each is capable of many discharge events with the smaller bodies.
After all of the above I must point out some craters really were created by meteors. There are boulders observed on bodies.
Several impact events on the Moon have been seen and recorded but from what I can find online these were small objects causing small craters.
My point is one should not assume all craters are due to meteors.
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