Why does Mercury have so many rayed craters? (2008 Nov 03)

[Jeauxy]

Dear Robert, etal,

Enjoy the Astronomy Picture of the Day every day and appreciate all the
good work to make this happen. Reminds me of being in college again
working on my physics degree.

You ask in today's http://antwrp.gsfc.nasa.gov/apod/ap081103.html the
following question:

"Why does Mercury have so many rayed craters?"

and I'd like to respond with a question to you: Given the prepondance of
evidence on the surface of Mercury, Moon, and Mars of interplanetary
plasma discharges which would readily explain the features found there,
why not accept the explanation postulated over fifty years ago by
Immanuel Velikovsky?

The huge mountain on Mars and the great canyon both resemble what one
might expect from an interplanetary plasma discharge without the need
for an ad hoc explanation that it was due to volcanoes and water
erosion. Plus we have records from ancient people of Mars's girth being
slashed by Venus's sword. A resonable explanation of people observing an
interplanetary lightning bolt between Mars and Venus. The slash is right
where one finds the great canyon on Mars.

I look at the rays on Mercury and see a crater which was eroded by the
direct point of contact by a giant plasma beam and the rays are remnants
of the discharged electricity spreading out from the center.

You say, "No one is sure." That's because they're looking in the wrong
place. The evidence is in front of their eyes and their blinders are on.

I'm not sure myself, but I can tell when everyone else is looking in the wrong place from time to time.

most cordially,
Jeauxy

[apodman]

I'm not sure myself, but I can tell when everyone else is looking in the wrong place from time to time.

I ain't often right
but I've never been wrong
It seldom turns out the way
it does in the song ...

people observing an interplanetary lightning bolt between Mars and Venus

... Once in a while
you get shown the light
in the strangest of places
if you look at it right

[apodman]

why not accept the explanation postulated over fifty years ago by
Immanuel Velikovsky?

Why not tell us about this explanation so we can make an informed judgment?

[iamlucky13]

The huge mountain on Mars and the great canyon both resemble what one
might expect from an interplanetary plasma discharge without the need
for an ad hoc explanation that it was due to volcanoes and water
erosion. Plus we have records from ancient people of Mars's girth being
slashed by Venus's sword. A resonable explanation of people observing an
interplanetary lightning bolt between Mars and Venus. The slash is right
where one finds the great canyon on Mars.

Volcanic activity and erosion, processes that are constantly observed in real-time on multiple bodies in the solar system are dismissible as ad hoc, but planetary scale plasma discharges that have never been observed by credible witnesses or described in a clearly interpretable manner by unverified or historical witnesses and require fundamentally rewriting most of the last 400 years of science are an event that fit expectations?

The theory doesn't have a leg to stand on.

[zooite871]

I've never heard of Immanuel Velikovsky; was he an astronomer?

[apodman]

I've never heard of Immanuel Velikovsky; was he an astronomer?

http://en.wikipedia.org/wiki/Worlds_in_Collision

In the book's preface, Velikovsky summarized his arguments:

Worlds in Collision is a book of wars in the celestial sphere that took place in historical times. In these wars the planet earth participated too. [...] The historical-cosmological story of this book is based in the evidence of historical texts of many people around the globe, on classical literature, on epics of the northern races, on sacred books of the peoples of the Orient and Occident, on traditions and folklore of primitive peoples, on old astronomical inscriptions and charts, on archaeological finds, and also on geological and paleontological material.

The book proposed that around the 15th century BCE, a comet or comet-like object (now called the planet Venus), having originally been ejected from Jupiter, passed near Earth (an actual collision is not mentioned). The object changed Earth's orbit and axis, causing innumerable catastrophes which were mentioned in early mythologies and religions around the world. Fifty-two years later, it passed close by again, stopping the Earth's rotation for a while and causing more catastrophes. Then, in the 8th and 7th centuries BCE, Mars (itself displaced by Venus) made close approaches to the Earth; this incident caused a new round of disturbances and disasters. After that, the current "celestial order" was established. The courses of the planets stabilized over the centuries and Venus gradually became a "normal" planet.

As usual, a contributor of an outlandish theory leaves us readers to do our own research.

[zooite871]

If that's what Velikovsky thinks, then what Jeauxy wrote is the same as saying the tooth fairy did it!

[apodman]

If that's what Velikovsky thinks, then what Jeauxy wrote is the same as saying the tooth fairy did it!

With his giant sword and ray gun.

[BMAONE23]

A more likely explanation for the location of the Martian Volcanic complex and the surrounding raised topography can be theorized by examining this APOD from June 28, 2001. The raised volcanic complex and surrounding relatively higher topographic region lies in the northern hemisphere centered between 0deg & 45deg N Lat and is roughly centered at 110deg W Longitude. While the Hellas Impact basin is located between -30 & -55 deg S Lat and is centered at 70deg E Longitude (at almost exactly opposing planetary locations)
So I feel it is more likely that the Martian Volcanic Plateau was raised by the kinetic energy imparted by the Hellas impact incident. Rather than that surmised complex planetary interaction between Venus and Mars. Orbits that are That Chaotic, won't miraculously stabilize over a few thousand years.

[Frenchy]

The atmosphere of Mercury could have boiled itself away and formed many of these craters, couldn't it?

[Chris Peterson]

The atmosphere of Mercury could have boiled itself away and formed many of these craters, couldn't it?

No, for many reasons. Mercury is too small to have ever had much atmosphere. Atmospheres can't "boil" away, they are simply lost (slowly) over time if no mechanism exists (as on Earth) to replenish them. And most important, the structures are clearly formed by impacts.

[BMAONE23]

The atmosphere of Mercury could have boiled itself away and formed many of these craters, couldn't it?

I have often wondered myself about "Mercury-The early years" and if, given it's high metallic ratio and relative core size, the planet might actually be the core remnant of a small Gas Planet whose ptmosphere has been stripped away by the sun.

[JohnD]

The atmosphere of Mercury could have boiled itself away and formed many of these craters, couldn't it?

I have often wondered myself about "Mercury-The early years" and if, given it's high metallic ratio and relative core size, the planet might actually be the core remnant of a small Gas Planet whose ptmosphere has been stripped away by the sun.

On another site, a poster signs off with, "I say there are pixies at the bottom of my garden - now you prove I'm wrong". They are, of course, tongue-in-cheek.

Nice idea,in view of extrasolar gas giants close to their sun, but where is the evidence for your pixie?

John

[BMAONE23]

The only evidence that I can surmise would be the apparent metallic core size relative to the remainder of the planet and how this is different from all other rocky planetary bodies in the solar system. This uniqueness may signify that Mercury had a vastly different past. If it had a large gaseous body surrounding it, and this atmosphere were to have been stripped away by solar activity a couple billion years ago, where would the proof be? The only thing to compare now is the remnant, the relative core size, and density relative to size.

[Chris Peterson]

The only evidence that I can surmise would be the apparent metallic core size relative to the remainder of the planet and how this is different from all other rocky planetary bodies in the solar system. This uniqueness may signify that Mercury had a vastly different past. If it had a large gaseous body surrounding it, and this atmosphere were to have been stripped away by solar activity a couple billion years ago, where would the proof be? The only thing to compare now is the remnant, the relative core size, and density relative to size.

There might simply be no way to know with any certainty what Mercury's history was, at least by looking at Mercury itself. A more confident answer may come from modeling of the formation and early history of the Solar System. Such models are becoming increasingly good, and researchers seem to have more confidence that they will be able to understand the formation of our system. We can't go back in time, but our recently acquired ability to watch- in some detail- other planetary systems forming, along with powerful computer models, bodes well for understanding how Mercury (and all the other elements of the Solar System) formed.

[sfcraiger]

dry skin from sunburn?

[BMAONE23]

In sticking witn my hypothysis about Mercury being a larger gas planetary core remnant:
Perhaps Mercury formed closer to the sun as a failed Gas Giant say perhaps 1/4 Neptunes size and over the course of time the gas was blown away by the solar wind, or perhaps even stripped away by the solar gravity as the sun formed. The reduction in mass coupled with the now unneeded orbital speed caused Mercury to relocate to a progressively farther orbit and once there was a sufficient reduction in gas, the core became exposed to the solar heat. This baked the surface perhaps carbonizing most of it. Later impacts in the early solar system formation then liberated the brighter subsurface material and distributed it in the familier Ray pattern over the carbonized older surface.

With the gradual elimination of the atmosphere, the pounding of the surface during the solar system formative years could also have robbed the planet of kinetic energy causing it's orbit to eventually stabilize where it is today.

This scenereo might be proven, to a certain extent IF the surface is in fact carbonized to a certain extent.

[rigelan]

You can stick with Mercury being a gas giant - I will vote against it.

I think the orbits of the first four planets seem too close together to form gas giants. The gas giants in our solar system have swept away a huge portion of objects in their orbits - the next planet is no closer than 4AU any of the gas giants. If a gas giant was where mercury was, I propose it would have swept away the orbit of Venus, and possibly Earth too.

[astrolabe]

Hello BMAONE23,

Interesting senario you've presented here. I've forgotten whether or not Mercury has a locked rotation in which one side always faces the sun. If so then the planet's possibly loss of it's magneto properties aided in the loss of a previous atmosphere.Interesting proposal indeed. Mercury's ancient orbit could have been highly eliptical which could be a subject of curiosity in the facinating developement of models WRT the evolution of our Solar System

[Dr. Skeptic]

Another - - Point-to-Ponder - -

There is a reason the average density of the planets decrease as the distance from the Sun increases. Emerging to life from a protostar the Sun's solar wind energy easily carried the lighter elements (H, He,C,N,O ...) from the accretion disk out to and past the distance of the gas giants while Fe,Ni, Co ... concentration increases proportionally to proximity to the Sun.

Mercury would have needed to be a protoplanet residing in the accretion disk to resemble a gas giant.

[Dr. Skeptic]

Hello BMAONE23,

Interesting senario you've presented here. I've forgotten whether or not Mercury has a locked rotation in which one side always faces the sun. If so then the planet's possibly loss of it's magneto properties aided in the loss of a previous atmosphere.Interesting proposal indeed. Mercury's ancient orbit could have been highly eliptical which could be a subject of curiosity in the facinating developement of models WRT the evolution of our Solar System

Mercury's rotation is locked in a 3:2 rotation to Earth. Coincidence?

[Chris Peterson]

Mercury's rotation is locked in a 3:2 rotation to Earth. Coincidence?

I assume you mean it's in a 3:2 resonance with the Sun, not the Earth. And it's no coincidence; tidal locking need not be 1:1.

[Dr. Skeptic]

Mercury's rotation is locked in a 3:2 rotation to Earth. Coincidence?

I assume you mean it's in a 3:2 resonance with the Sun, not the Earth. And it's no coincidence; tidal locking need not be 1:1.

Nope, with the Earth. It's either gravitational or magnetic tidal lock or a very strange coincidence. Wikipedia can explain it better that I can.

http://en.wikipedia.org/wiki/Mercury_(planet)

[BMAONE23]

You can stick with Mercury being a gas giant - I will vote against it.

I think the orbits of the first four planets seem too close together to form gas giants. The gas giants in our solar system have swept away a huge portion of objects in their orbits - the next planet is no closer than 4AU any of the gas giants. If a gas giant was where mercury was, I propose it would have swept away the orbit of Venus, and possibly Earth too.

I'll have to think about that and see if I can make it work with 3 other planets to consider.

[apodman]

Wikipedia can explain it better that I can.

The face that Mercury shows Earth doesn't change much from one pass to the next, which is what originally led astronomers to believe that one side of Mercury always faced the Sun.

The reason that the face that Mercury shows Earth doesn't change much from one pass to the next is that Mercury passes Earth about every 116 days* while Mercury completes two full rotations in 117.4 days.

The closeness of the 116 days (which depends on Mercury's year length and Earth's year length) to the 117.4 days (which depends on Mercury's day length) is a coincidence.

That is what the Wikipedia was trying to say.

---

* In 116 days, Mercury completes about 1.32 88-day orbits while Earth completes about 0.32 365.25-day orbits. So in 116 days, Mercury completes 1 more orbit than Earth. All these numbers are approximations to illustrate the point, not exact figures. Timing between passes varies anyway due to elliptical orbits.