Mercury’s Rotation Class Description Report Raw Data Mercury’s Rotation Summary [Updated 2/8/07] The Urantia Book states that tidal friction causes the axial rotation of heavenly bodies to slow to a stop (relative to the body around which they revolve) and cites Mercury and the moon as examples. It has long been well established that the rotation of the moon has stopped, and it was also believed at the time of publication (1955) that Mercury's rotation had ceased. Though the widely held belief at the time of The Urantia Book’s publication was that Mercury had stopped rotating, when The Urantia Book addressed the subject of tidal friction slowing orbiting bodies to a stop, it did not state that Mercury had stopped and only portrayed the moon as a body that had stopped rotating due to tidal friction. In 1965 we learned that Mercury does have a slow rotation. The Urantia Book avoided the trap of agreeing with science that was wrong, but widely accepted, at the time of its publication.

Mercury’s Rotation: Class C Topic
[Updated 10/11/07]

The Urantia Book, in discussing how tidal friction will eventually slow the rotation of orbiting bodies to stop, does not state that Mercury has come to a stop, even though it lists Mercury as one of the best examples of this gravitational effect. It does, however, give the moon as an example of an orbiting body that has stopped its rotation due to the effect of tidal friction. At the time The Urantia Book was published, it was universally believed that Mercury’s axial rotation had come to a stop. A decade after The Urantia Book's publication scientists discovered that Mercury still has a very slow rotation. Because The Urantia Book simply avoided agreeing with science that was bad at the time, this is placed in the Class C category.

Mercury’s Rotation Report
Prepared by Halbert Katzen, JD with special thanks to Phil Calabrese, PhD and Chris Halvorson, PhD
[Updated 2/5/08]

The Urantia Book states that, “The planets nearest the sun were the first to have their revolutions slowed down by tidal friction. Such gravitational influences also contribute to the stabilization of planetary orbits while acting as a brake on the rate of planetary-axial revolution, causing a planet to revolve ever slower until axial revolution ceases, leaving one hemisphere of the planet always turned toward the sun or larger body, as is illustrated by the planet Mercury and by the moon, which always turns the same face toward Urantia[Earth].”¹

Wikipedia.com makes the following commentary on the subject:

“For many years it was thought that Mercury was synchronously tidally locked with the Sun, rotating once for each orbit and keeping the same face directed towards the Sun at all times, in the same way that the same side of the Moon always faces the Earth. However, radar observations in 1965 proved that the planet has a 3:2 spin-orbit resonance, rotating three times for every two revolutions around the Sun; the eccentricity of Mercury's orbit makes this resonance stable — at perihelion, when the solar tide is strongest, the Sun is nearly still in Mercury's sky. The original reason astronomers thought it was synchronously locked was because whenever Mercury was best placed for observation, it was always at the same point in its 3:2 resonance, hence showing the same face.”²

This discovery was made ten years after publication of The Urantia Book.

Notwithstanding that The Urantia Book avoided the pitfall of agreeing with science that was wrong at the time of its publication, there is still disagreement between The Urantia Book and contemporary science. While The Urantia Book says that tidal friction causes “a planet to revolve ever slower until axial revolution ceases,” contemporary science is now supporting the notion that Mercury has a stable 3:2 spin-orbit resonance.

Whether further research will harmonize with The Urantia Book's assertion that tidal friction will cause the planet to cease rotating is still an open question. And whether such harmony will occur any time soon is doubtful because current observations suggest that its 3:2 spin-orbit resonance is stable. Nonetheless, additional observations may yet reveal that Mercury's axial rotation has a measure of instability that will eventually knock it out of what currently appears to astronomers as a stable 3:2 spin-orbit resonance.

Mercury is known for having an “eccentric” orbit. Wikipedia.com states, “The orbit of Mercury is the most eccentric of the major planets, with the planet's distance from the Sun ranging from 46,000,000 to 70,000,000 kilometers.” This eccentricity creates variations in the speed of its orbit. Tidal friction, which is an ongoing process, may yet cause a shift in both the orbit and axial rotation of Mercury.

Some research has gone in the direction of calculating such a probability/possibility that Mercury could have developed a 1:1 spin-orbit resonance, or to it put another way, no axial revolution with respect to the sun. From l'Observatoire de Paris' analysis in a report titled The explanation of Mercury's capture into the 3:2 spin-orbit resonance as a result of its chaotic orbital dynamics , we have the following:

“With their extended numerical simulations, the researchers found that the capture into the 3:2 resonance is in fact the most probable outcome of the planet, with 55.4 % chances to occur. The remaining possibilities being a capture into the 1/1 resonance (2.2%) as for the Earth-Moon system, capture into the 2/1 resonance (3.6%), or no capture (38.8%). Temporary capture into higher order resonances (5/2 or 3/1 for example) are possible, but none of them survived over the full integration, as they become destabilized when the eccentricity of Mercury decreases to low values.”³

This leaves the question a bit open by indicating that other possibilities existed. However, the vast majority of research on the subject does not address other possibilities the way they are talked about in the above article and there seems to be a fairly uniform acceptance of the notion that the rotation is stable for the foreseeable future. Even this article suggests that the other possibilities were with respect to things that could have happened during Mercury's initial stages of development, not future developments. With regard to a separate issue, some people have suggested The Urantia Book says that Mercury's axial revolution has come to a stop and that, therefore, The Urantia Book is incorrect with regard to its statements about Mercury. This opinion comes from extracting the following phrases from the sentence in which they occur: “leaving one hemisphere of the planet always turned toward the sun or larger body, as is illustrated by the planet Mercury.”

This is a flawed analysis of the phrases because they are taken out of context both within the sentence from which they are taken and with respect to the context created by the previous sentence. Proper interpretation of these phrases requires that they not only be put fully in the context of the sentence in which they occur but also in the context of a sentence-to-sentence analysis.

The previous sentence states: “The planets nearest the sun were the first to have their revolutions slowed down by tidal friction.” Here it is important to note that the larger context is specifically about our solar system and the lead-in sentence of the paragraph, quoted above, relates to planets in our solar system being slowed by tidal friction. It does not say that any of the planets have stopped due to this effect. The slowing is the issue being noted and there is no mention here or anywhere else of any planet having stopped already. Though this first sentence would not be inconsistent with a planet having stopped, it certainly does not imply or suggest such a thing either. 

Next, and more importantly, we must appreciate the phrases within the context of the sentence in which they occur. 

The phrases in question are qualifying/clarifying phrases, additions to the main point of the sentence. This interpretation is necessary and supported by the fact that the first part of the sentence, “Such gravitational influences also contribute to the stabilization of planetary orbits while acting as a brake on the rate of planetary-axial revolution, . . .” is a complete thought within itself. A period could have been put at the end of this first part of the sentence and it would have been grammatically correct. Not only would it have been grammatically correct, but additionally and more to the point, it would have been instructive all by itself because it brings together two distinct issues. The one issue being the stabilization of orbits and the other being the braking effect on axial revolution. By starting with a complete thought, grammatical conventions require us to interpret what comes afterwards and is separated by commas in terms of how it fundamentally relates to this initial concept/complete thought.

Now let's consider the first qualification/clarification, separated by a comma, that comes after the complete thought — “causing a planet to revolve ever slower until axial revolution ceases, . . .” The clarification is that the process mentioned above, as regards the braking/slowing of the planets (clearly, this is not addressing the orbital stability issue), is that eventually there is finality to the process, the planet stops. This does not imply that any particular planet has reached the point of having stopped because everything that comes before this comma-separated phrase is in general terms. Therefore, this phrase should not be construed to mean that stoppage has actually occurred, only that the process of tidal friction will eventually lead to this result.

Then we get the next comma-separated phrase which qualifies/clarifies the previous phrase — “leaving one hemisphere of the planet always turned toward the sun or larger body, . . .” What this phrase does by way of clarification of the previous phrase is to state specifically what is meant by stopped (i.e. one hemisphere always turned toward the sun) and then it adds an additional clarification that this process not only relates to planets but also to other orbiting bodies. This is what the “or larger body” contributes to the clarification of the main point regarding the effects of tidal friction; it expands the tidal friction effect to other orbiting spheres.

Then comes the next clarification —“as is illustrated by the planet Mercury and by the moon, . . .” So now the question is, “What is illustrated by the planet Mercury and the moon, that they are both examples of the effects of tidal friction (something that eventually leads to stoppage) or that they have both stopped?” To answer this question we must go to the last qualifying/clarifying and comma-separated phrase — “which always turns the same face toward Urantia[Earth].” 

This last qualifying phrase distinguishes the moon from Mercury. It could have just as easily said something like, “both of which now turn the same hemisphere toward the body around which they orbit.” But it does not do this. Instead, it distinguishes these two bodies from each other by only addressing the status of the moon. By distinguishing the two spheres from each other, it leaves Mercury standing alone as an example of the main subject of the sentence, i.e. that tidal friction slows planets down, eventually to a stop, and first affects the planets closest to the sun.

1. UB 57:6.2 This mode of citation to The Urantia Book provides the chapter (referred to as "Papers" in The Urantia Book), then the section, followed by the paragraph number.
2. http://en.wikipedia.org/wiki/Planet_Mercury
3. http://www.obspm.fr/actual/nouvelle/jul04/merc.en.shtml, second to last paragraph.

Mercury’s Rotation Raw Data

UB 57:6.2

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

http://www.obspm.fr/actual/nouvelle/jul04/merc.en.shtml

http://cseligman.com/text/planets/mercuryrot.htm

http://cseligman.com/text/planets/DayOnMercury.swf

http://edition.cnn.com/2007/TECH/space/01/22/moon.destiny/index.html
Earth's moon destined to disintegrate