The Atomic Comet: The Ionization Enigma

A strange aspect of the Space Age is it’s failure to enlighten the dark recesses of astronomy.

For example:

The standard explanation for the light emitted by comets has remained constant for over 100 years.

The light of the comet therefore proceeds from two sources: one the incandescence of gases, the other the sunlight reflected from the solid parts.

1911 Encyclopædia Britannica – Volume 6 – Comet

Both the coma and tail are illuminated by the Sun and may become visible when a comet passes through the inner Solar System, the dust reflects Sunlight directly while the gases glow from ionisation.

This particular facet of astronomy became frozen and fossilised in 1950 when Fred Whipple “visualized” a comet as a “conglomerate of ices” that [in his mind’s eye] reflected sunlight.

A simple calculation shows that Rayleigh scattering by these molecules is negligible compared to the direct reflection of sunlight from the cometary nucleus at the rates of sublimation assumed in the present paper.

A Comet Model. II. Physical Relations for Comets and Meteors.
F L Whipple – Harvard College Observatory
Astrophysical Journal – Vol. 113 – P .464 – May 1951


However, from the very beginning, there were very obvious problems associated with the light emitted by Fred Whipple’s “visualized” frozen cometary conjecture.

In 1954 Fritz Kahn very coolly noted a “hidden source of energy” was required to produce and ionise a cometary cloud of carbon monoxide and cyanogen.

A comet’s tail is by far the most extended object in the solar system, spreading out up to as much as 300,000,000 kilometers.

Yet it is not an “object” ; it is luminescent gas, like that of the Northern Lights .

The spectroscope reveals that the luminescent atoms are those of ionized carbon monoxide, CO, and cyanogen, CNO.

This is puzzling, because to produce these carbon-compounds and to ionize them requires considerable energy ; we have not yet been able to divine this hidden source of energy.

Design of The Universe – Fritz Kahn – 1954

Click to access Design_Of_The_Universe-Fritz_Kahn-1954-377pgs-PHY.pdf

In 1982 this “hidden source of energy” was more discretely named The Ionization Enigma.

The Ionization Enigma

Solar protons and photons have frequently been considered inadequate for causing the ionized component of cometary gases: ionization rates of 10-6/s or less (Jockers, this meeting) seemed to give fewer ions than observed and to conflict with structures and brightness flares with time scales as short as 103.5 s (Wurm 1963, Wurm and Mammano 1967).

ESO Workshop on The Need for Coordinated Ground-based Observations of Halley’s Comet – Paris, 29 – 30 April 1982
Edited by P. Veron, M. Festou and K. Kjar – September 1982

Click to access The_Need_for_Coordinated_Ground-based_Observations_of_Halley’s_Comet_A1b.pdf

By the end of the decade The Ionization Enigma had been quietly dispatched to the black memory hole of astronomy [from where no enlightenment escapes] after it was realised solar irradiance couldn’t explain away Comet Halley’s increased Total Visual Magnitude as it sped away from the Sun after perihelion.

While the heliocentric brightness (H) variation with respect to heliocentric distance (r) did not follow expectations closely, P/Halley’s maximum brightness during 1986 Feb.-Apr. fell somewhere between the most pessimistic and the most optimistic forecasts.

Click to access nph-iarticle_query

The arcane attitudes of astronomy remained frozen and fossilised even after the Giotto mission discovered the [unmentionable] Reflected Light Enigma caused by Comet Halley’s “blacker than coal” nucleus surrounded by a cloud of tiny specks that resembled “cigarette smoke”.

The surface of the nucleus was very dark – blacker than coal
Most of the dust was no larger than specks of cigarette smoke.

European Space Agency – Giotto – Science Results

A decade after Comet Halley the mysterious “hidden source of energy” resurfaced in the form of cometary X-Rays that were “about 100 times brighter than even the most optimistic predictions”.

A team of U.S. and German astrophysicists have made the first ever detection of X-rays coming from a comet.

Their discovery of a strong radiation signal — about 100 times brighter than even the most optimistic predictions — was made March 27, 1996, during observations of Comet Hyakutake using Germany’s orbiting ROSAT satellite.

The strength of the X-ray emission from Comet Hyakutake took the astronomers by surprise, and they are also puzzled by the rapid changes in their intensity.

X-rays were never found from a comet before, and scientists had optimistically predicted an intensity that turned out to be about 100 times weaker than the radiation actually detected by ROSAT.

Explaining the unexpected bright X-ray emission is the next major task for the science team.

First X-Rays from a Comet Discovered
Goddard Space Flight Center – ROSAT Guest Observer Facility

This false-color image shows comet Tempel 1 as seen by Chandra X-ray Observatory on June 30, 2005, Universal Time.

The observatory detected X-rays with an energy of 0.3 to 1.0 kilo electron Volts.

The bulk of the X-rays were between 0.5 and 0.7 kilo electron Volts.

X-ray Eyes on Tempel – 3 July 2005
Jet Propulsion Laboratory – California Institute of Technology

Cometary X-Rays “surprised researchers” because X-Rays are associated with high temperatures.

Comets were found to emit X-rays in late-March 1996.
This surprised researchers, because X-ray emission is usually associated with very high-temperature bodies.

The “surprised researchers” didn’t have long to wait before they learnt the flow of ions around a comet “are heated to about 1 million Kelvin”.

Deep Space 1 flew by comet Borrelly on September 22, 2001 and took these measurements with its plasma instruments between 90,000 kilometers (56,000 miles) and 2,000 kilometers (1,200 miles) away.

These data show that the flow of ions around the comet’s rocky, icy nucleus (the center of the deep V-shaped feature) is not centered on the comet’s nucleus as scientists expected before the Borrelly flyby.

Ions in the turbulent flow are heated to about 1 million Kelvin (2 million degrees Fahrenheit) causing the bands of ions to appear broad and jagged compared to the solar wind.

Photojournal – PIA03503: Comet Borrelly Nucleus Found to the Side
Jet Propulsion Laboratory – California Institute of Technology

After some humming and harring the mainstream decided cometary X-Ray emissions are caused by an “interaction between comets and the solar wind”.

One preliminary theory is that X-ray emission from the Sun was absorbed by a cloud of gaseous water molecules surrounding the nucleus of the comet, and then were re-emitted by the molecules in a process physicists call “fluorescence.”

A second possible explanation is that the X-rays are produced from the violent collision between the comet material and the supersonic “wind” of plasma and particles streaming away from the sun.

First X-Rays from a Comet Discovered
Goddard Space Flight Center – ROSAT Guest Observer Facility

The X-rays observed from comets are caused by an interaction between highly charged oxygen in the solar wind and neutral gases from the comet.

X-ray Eyes on Tempel – 3 July 2005
Jet Propulsion Laboratory – California Institute of Technology

The X-rays are thought to be generated by the interaction between comets and the solar wind: when highly charged ions fly through a cometary atmosphere, they collide with cometary atoms and molecules, “ripping off” one or more electrons from the comet. This ripping off leads to the emission of X-rays and far ultraviolet photons.

This is the same argument that’s used to explain the production of X-Rays in the Earth’s Geocorona where “heavy ions of carbon, oxygen and neon in the solar wind” collide with hydrogen atoms.

Observation Dates – July 26, 2001 Observation Time – 5 hours

The Chandra observations (right) of the bright portion of the Moon detected X-rays from oxygen, magnesium, aluminum and silicon atoms.

The X-rays are produced by fluorescence when solar X-rays bombard the Moon’s surface.

Chandra’s observations have also solved a decade-long mystery about X-rays detected by ROSAT that were thought to be coming from the dark portion of the Moon.

It turns out that these X-rays only appear to come from the Moon.

Chandra shows that the X-rays from the dark moon can be explained by radiation from Earth’s geocorona (extended outer atmosphere) through which orbiting spacecraft move.

The geocoronal X-rays are caused by collisions of heavy ions of carbon, oxygen and neon in the solar wind with hydrogen atoms located tens of thousands of miles above the surface of Earth.

During the collisions, the solar ions capture electrons from hydrogen atoms.

The solar ions then kick out X-rays as the captured electrons drop to lower energy states.

The Moon: Lunar Prospecting With Chandra – 16 Sept 2003
Chandra X-Ray Observatory

This template explanation works for the Earth’s Geocorona and the Dayside of the Moon.

But it fails to explain away the intensity of X-Rays produced by Comet Hyakutake.

The X-Ray intensity in Comet Hyakutake’s coma appears to be two orders of magnitude greater than in the Earth’s Geocorona and one order of magnitude greater than on the Dayside of the Moon.

When compared to the Earth’s Geocorona the X-Rays produced by Comet Hyakutake are “about 100 times brighter than even the most optimistic predictions”.

In other words:

Comets are the “hidden source of energy” noted by Fritz Kahn in 1954.

Gallery | This entry was posted in As Above So Below, Astrophysics, Atmospheric Science, Atomic Comet, Comets, Earth, History, Moon, Science, Solar System. Bookmark the permalink.

4 Responses to The Atomic Comet: The Ionization Enigma

  1. oldbrew says:

    Fascinating stuff. ‘A comet’s tail is by far the most extended object in the solar system, spreading out up to as much as 300,000,000 kilometers’ – a heck of a long way.

    But in the case of Hyukatake:
    ‘at least 570 million km (360 million miles; 3.8 AU) long. This is almost twice as long as the previous longest-known cometary tail, that of the Great Comet of 1843, which was 2.2 AU long’

  2. Pingback: The Atomic Comet: Carbon Cousins | MalagaBay

  3. Pingback: The Atomic Comet: Neutron Bombs | MalagaBay

  4. Pingback: Alaskan Muck: Indelicate Details | MalagaBay

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.