Pluto found to be geologically active: Where does its heat come from?

Image of Pluto taken from the New Horizon's spacecraft. (credit: NASA)

Image of Pluto taken from the New Horizon's spacecraft. (credit: NASA)

Posted by P. LaViolette

July 16, 2015

The recent fly-by of Pluto has given scientists something to puzzle over.  The images relayed back by the New Horizon spacecraft showed that its surface was devoid of craters.  This indicates that either Pluto is a very young addition to our solar system or that it is geologically active and periodically resurfaces itself covering over any crater features.  Since Pluto is believed to consist of 50% water ice and 50% rock, it should not take much  internal heat generation to liquify the ice and produce periodic liquid water outflows (covered with a thin ice layer due to surface freezing).  But astronomers are puzzled by where Pluto would get sufficient heat to do this.

See for example this posting:

Subquantum kinetics had offered the answer to this mystery as much as 20 years ago: Namely, it predicts that Pluto generates genic energy in its interior.  It predicted that heat energy (genic energy) is spontaneously produced in the interior of Pluto giving Pluto a hot interior.  The latest prediction for the spontaneous heat flux from Pluto's interior is to be found in the 4th edition of Subquantum Kinetics (2012) which gives it as: 2.3 X 1019 erg/s.  But with the new data on the mass and radius of Pluto from this recent encounter, this estimate must be revised downward to 1018 erg/s.

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Here are some figures to update the subquantum kinetics genic energy prediction for Pluto which is contained in the 4th edition of SQK:

Pluto's mass: 1.31 X 1025 grams (6.6 X 10-9 solar masses)

Pluto's radius: 1.19 X 108 cm

Heliocentric distance: 4.5 X 1014 cm

Genic photon energy amplification coefficient:  = 1.4 X 10-18 s-1

Heat capacity: 2.7 X 107 erg/g/K

Average internal temperature: 2000 K

Pluto's internal genic energy luminosity: 1018 erg/s  (2.6 X 10-16 solar luminosities)


This genic heat flux predicted to come from Pluto may be compared with the genic energy heat flux predicted to come from the Moon which is estimated to be 2.7 X 1018 erg/s.  The Moon's genic heat flux is predicted to be larger, but the Moon is also somewhat larger, having a radius 46% larger than that of Pluto.  In terms of genic energy heat flux per unit area, that coming from the surface of Pluto is comparable to that coming from the surface of the Moon (see text box below).  So our assumption that Pluto has a similar average internal temperature to that of the Moon (2000 K or ~1700 Centigrade) is reasonable.  But the Moon is made of rock whereas Pluto is half rock and half water ice.  So since ice has a much lower melting point, ~273° Kelvin as compared with 1500° Kelvin,  there is a very good chance that this internal heat flux, even though it is one third that of the Moon, could melt Pluto's ice and cause resurfacing.

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The total heat flux observed from the Moon per unit surface area, including the contribution of crustal radioactivity is 18 erg/s/cm2 (7 X 1018 erg/s ÷ 3.8 X 1017).  By comparison the genic energy flux per unit surface area estimated to come from Pluto is ~6 erg/s/cm2, or just 30% of that coming from the Moon's surface.


Given that Pluto has an albedo of ~50%, at its present distance from the Sun its surface absorbs an average solar heat flux of 8 X 1018 erg/s.  Hence its genic energy luminosity is about 12% of its insolation, meaning that it should exhibit an internal luminosity excess-to-solar influx ratio of about one sixth of that observed for Jupiter and Saturn.  This prediction can be checked by infrared measurements that hopefully will soon be received from the New Horizons spacecraft.  Even if the magnitude of the above energy excess estimate is off by a factor of three, its detection should still be considered a plus for subquantum kinetics, since standard theory expects no such energy excess for Pluto.

In the case of Pluto, it internal heat flux will play a far more important role relative to the solar influx than is the case for the Moon. For example, the ratio of the Moon's internal energy flux to its solar input flux is almost three orders of magnitude lower than Pluto's genic-to-solar energy ratio.

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