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Mercury’s crust is magnetized

NASA/Johns Hopkins University Applied Physics Laboratory Figure 1. MESSENGER spacecraft shown over colour-enhanced image of Mercury. Magnetometer at end of 12-foot boom to left. Graphics: NASA/Johns Hopkins University Applied Physics Laboratory.
Figure 1. MESSENGER spacecraft shown over colour-enhanced image of Mercury. Magnetometer at end of 12-foot boom to left. Graphics: NASA/Johns Hopkins University Applied Physics Laboratory.

More good news for creation science

by

Published: 18 July 2012 (GMT+10)

NASA’s MESSENGER spacecraft (figure 1) is continuing to produce surprising new evidence that Mercury’s magnetic field is as young as the Bible says. Since March 2011 the spacecraft has been in a near-polar orbit around Mercury. By now it has orbited the planet nearly a thousand times, repeatedly passing over the entire surface. Swooping low over the northern volcanic plains, the spacecraft discovered that the planet’s outer crust in that region is strongly magnetized.1 The strongest magnetization coincides with a broad topographic rise near the center of those plains. That leads the analyzing team to believe that the magnetization comes from basalt solidified from lava flowing up out of the deeper crust throughout the plain.

The crust magnetization is nearly vertical, just as is the planet’s overall magnetic field in those high latitudes. But MESSENGER found that the magnetization is opposite to the direction of today’s field, indicating that Mercury has reversed the direction of its field at least once in the past. The team of analysts says this

“ … implies that the magnetization is a remanent [remaining, permanent] magnetization acquired [in the past] when Mercury’s magnetic field was of the opposite polarity, and possibly stronger, than the present field.”

The last phrase above would have been more accurate if it had said, “ … and very probably much stronger than the present field.” Here’s why: The amount of magnetization depends on the amount and mineral form of iron in the rock, and on the strength of the field when it cools. The analysts conjectured that the iron in the crustal rocks is pure,2 an unlikely composition that might allow the past magnetizing field to be weak. However, the measured magnetism of basalts here on earth suggests that Mercury’s crustal basalts acquired their magnetism in a field at least ten times stronger than Mercury’s field today.3

This adds to the string of surprises Mercury’s magnetic field has given uniformitarian4 space scientists. Before Mariner 10 zoomed by the planet in 1974 and 1975, experts had expected the planet to have zero field. Instead, those flybys showed that Mercury has a significant magnetic field, about 1% of Earth’s. Since then, theorists have tried many versions of the ‘dynamo’ theory (which imagines a planet’s core acting like an electric generator) to explain how Mercury could have a field and sustain it for eons. In the last few years, they have been trying to understand why the field is so low compared to Earth’s.

Especially relevant here, all versions of the dynamo theory assert that, except for brief periods when the field might have reversed itself, Mercury’s field should have stayed at much the same strength throughout the alleged billions of years of its existence. Evidence for a large decrease of the field sometime in the past adds to the theorists’ perplexity. That may be why the analyzing team apparently wanted to dilute that detail.

Magnetized crust validates a prediction

In contrast, the above result vindicates one of two scientific predictions about Mercury’s magnetic field made by a biblically-based creationist theory. I offered it in 1984 to explain how God created magnetic fields of planets in our solar system.5

If the theory were correct, the article said, then

“Older igneous rocks from Mercury or Mars should have natural remanent magnetization, as the Moon’s rocks do.”

By ‘older,’ I meant rocks that formed not long after creation, while the fast-decaying magnetic fields of those two planets would be still moderately strong. I said ‘from’ because I was picturing that rocks from Mars and Mercury would have to be brought back by astronauts for lab tests, the way they did for Moon rocks. I had no idea that low-orbiting spacecraft would someday be able to detect crustal magnetizations. But new space science developments have opened the door to such measurements, in 1997–1999 for Mars,6 and during the last year for Mercury.

Fast-fading field validates a second Mercury prediction

Measurements MESSENGER made from orbit last year, compared with the 1975 Mariner 10 data, show that Mercury’s magnetic field has weakened by nearly 8% in the past 36 years, an astonishingly fast decrease. That supports a prediction in the 1984 paper:

“Mercury’s decay rate is so rapid that some future space probe could detect it fairly soon. In 1990 the planet’s magnetic moment should be 1.8 percent smaller than its 1975 value.”7

The observed rate agrees with Mercury’s core having an electrical conductivity close to that of Earth’s core.8 The next issue of Journal of Creation will give more details.9

The fast rate of decay (half-life of 320 years) implies the crust was magnetized only thousands of years ago.

Valid predictions are important

The above two items for Mercury’s magnetic field, its fast fading and its magnetized crust, complete the five predictions in my 1984 paper, all of which spacecraft have now verified.10 Also, I have extended the application of the theory to other astronomical objects inside the solar system (asteroids, meteorites, moons of other planets) and outside the solar system (stars, magnetic stars, white dwarfs, pulsars, magnetars, galaxies, the cosmos itself). Amazingly (at least for me), this theory fits these objects well, too.11

The main importance of the good fit to known data and the verified predictions12 is that they support the biblical account of creation and Scripture’s young age for the cosmos. The theory could fit the magnetic data we now have for the solar system only if:

  1. The original material God created were water (which God then transformed to the present materials), per 2 Peter 3:5 (Greek and NAS) and other passages.
  2. The Earth and solar system were close to the 6,000-year age given by a straightforward reading of Scripture.

Thus, magnetic fields in the cosmos serve as God’s signature on his creation, and like everything in the heavens, they give glory to Him (Psalm 19:1).

References

  1. Purucker, M.E. et al., Evidence for a crustal magnetic signature on Mercury from MESSENGER magnetometer observations, 43rd Lunar and Planetary Science Conference, The Woodlands, Texas, USA., March 19–23, 2012, archived at www.lpi.usra.edu/meetings/lpsc2012/pdf/1297.pdf. My thanks to Andrew Lamb of CMI for alerting me to this article. Return to text.
  2. Mason, B. and Berry, L.G., Elements of Mineralogy, W.H. Freeman and Company, San Francisco, CA, USA, p. 212, 1968. Near the end of their abstract the MESSENGER team suggests that the magnetic carrier in the rock consists of easy-to-magnetize ‘single-domain’ (=tiny) particles of ‘native’ (= pure = elemental) iron. But such a composition is rare in basalts, as this reference notes, because normally tiny particles of elemental iron would chemically combine quickly with other elements in hot silicate rock as it cooled down from its molten state. Return to text.
  3. Coe, R.S. et al., Geomagnetic paleointensities from radiocarbon-dated lava flows on Hawaii and the question of the pacific nondipole low, Journal of Geophysical Research 83(B4):1740–1756, 10 April 1978. The ordinate of Fig. 1(a) at zero ‘TRM’ gives the initial ‘NRM’ (magnetization) of one basalt sample, ~23 A/m (10-3 emu/cm3 = 1 A/m) from cooling in a field of 51.4 µT (0.514 Gauss). Fig. 3 similarly gives a magnetization of ~2.9 A/m for basalt that formed in a field of 14.4 µT. Other references give a similar range of magnetizations for basalts. Ref. 1, Fig. 3, gives minimum magnetizations (to cause the observed perturbations to Mercury’s field) for various possible thicknesses of the magnetized layer. For 15 km thickness (below which depth the crust is probably too hot to retain magnetization for long), the minimum is 1 A/m. For the 2 km thickness the analysts say is a likely regional maximum, extrapolating the figure gives about 5 A/m for the crust magnetization. Using all the above figures gives us a magnetic field between 5 and 25 µT. Such intensities are considerably higher than today’s field in the high latitudes of Mercury, about 0.5 µT. I.e., these numbers imply the field was at least ten to fifty times higher when the crust cooled than today. Return to text.
  4. Uniformitarianism is the skeptical belief that ‘all continues just as it was from the beginning’ of the universe (2 Peter 3:4) without any large-scale interventions by God. It is the basic assumption behind long-age interpretations of geological, nuclear, and astronomical data. Return to text.
  5. Humphreys, D.R., The creation of planetary magnetic fields, Creation Research Society Quarterly 21(3):140–149, December 1984. Return to text.
  6. Connerney, J.E.P. et al., Magnetic lineations in the ancient crust of Mars, Science, 284:279–793, 30 April 1999. Return to text.
  7. Humphreys, ref. 5, p. 147, item 2 in conclusion. I estimated the 1.8% decrease by assuming a constant-rate decay from the strength at creation (from my theory) down to the strength in 1975, and then extrapolating from 1975 to 1990. Extrapolating further implies a 4.3% decrease from 1975 to 2011. The additional 3.5% (to make the 7.8% actually measured for the 36-year period) may be due to a non-constant decay rate, which perhaps steadily increased from creation until now. See Humphreys, ref. 9 for a reason why that may have occurred. Return to text.
  8. Smith, D.E., et al. Gravity field and internal structure of Mercury from MESSENGER, Science 336:214–217, 13 April 2012. These measurements show that Mercury’s core radius is a whopping 85% of the planet’s overall radius. The decay time depends on the product of core conductivity and the square of the core radius. The new figures reduce the estimate of Mercury’s core conductivity I made earlier, bringing it into line with those of Earth and Mars. Details in next reference. Return to text.
  9. Humphreys, D. R., Mercury’s magnetic field is fading fast—latest spacecraft data confirm evidence for a young solar system, Journal of Creation 26(2):6–8, August 2012, in press. My calculation of the decrease, giving 7.8 (± 0.8) %, re-analyzes the 1975 Mariner 10 data in terms of the zero tilt and significant offset MESSENGER found in 2011. Return to text.
  10. Humphreys, ref. 5, p. 147. There is also a less-important prediction: that Pluto will turn out to have no magnetic field when a spacecraft visits it. That should be in July, 2015 by NASA’s New Horizons space probe. The prediction rests on the assumption (from Pluto’s density) that Pluto is entirely ice, which I expected would have a low electrical conductivity. Uniformitarians also expect it to be entirely ice, so according to their ‘dynamo’ theories (which must have a fluid conducting interior), they also expect no magnetic field. Return to text.
  11. Humphreys, D.R., The creation of cosmic magnetic fields, Proceedings of the Sixth International Conference on Creationism, Snelling, A.A. (ed.), Creation Science Fellowship, Pittsburgh, PA, and Institute for Creation Research, Dallas, TX, pp. 213–230, 2008. Return to text.
  12. Humphreys, ref. 5, p. 147. As I pointed out in the conclusion, testable predictions are a counter-example to the frequent skeptics’ claim that creationists have no scientific theories because they offer no predictions that make the theories open to scientific testing. The fact that this theory has now passed five predictive tests—tests intimately linked to its central assertions—should give skeptics some reason to reconsider their position. Return to text.

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