Small Comet Images Pass the Ultimate Test,
Proving the Reality of Atmospheric Holes

. A new study of small comet observations from the Polar spacecraft shows conclusively that the atmospheric holes seen in the images from its ultraviolet Earth Camera are absolutely real--and not meaningless camera "noise," as some skeptics have claimed. These new results are being presented by University of Iowa researchers Louis A. Frank and John B. Sigwarth at the Fall Meeting of the American Geophysical Union in San Francisco on Dec. 9, 1997.

. Physicists Frank and Sigwarth found that the Polar data easily pass the ultimate test for the reality of the atmospheric holes. This ultimate test is based on one simple fact: if the atmospheric holes are real, then the number of holes detected in the images should decrease as the spacecraft's altitude increases. Why? Because as the satellite's altitude above the atmosphere increases, the apparent size of the atmospheric holes its camera sees should decrease, until most of the holes become just too small to be seen by the camera. On the other hand, if the data show no decrease in the number of atmospheric holes as the spacecraft's altitude increases, then the atmospheric holes are an instrumental artifact. This "altitude test" is generally accepted by the scientific community as the decisive evidence for or against the reality of the atmospheric holes. Figure 2

. Using Polar data from June 1, 1997--which are similar to those obtained on other dates--Frank and Sigwarth compared the low altitude data, when the Polar spacecraft was between 3 and 5 times the Earth's radius above the surface, to the high altitude data, when the spacecraft was between 5 and 8 Earth radii above the surface. On the day in question, a total of 5,650 holes appeared in the
images. For the same area in the images, the high altitude data showed an 80 percent drop in the frequency of atmospheric holes in comparison with the low altitude data.

. If the holes were an instrumental artifact, then obviously the frequency of the holes would not be dependent on the spacecraft's altitude and about the same number of holes should have been seen in the two altitude ranges. But more than five times as many holes were observed at the lower altitudes. "This result is a marvelous confirmation of the reality of atmospheric holes," notes Frank.

. This ultimate test could not be applied to earlier Dynamics Explorer-1 images because that spacecraft (with an apogee altitude of 23,300 km versus Polar's 50,510 km apogee) did not get high enough above the atmosphere for the atmospheric holes to elude detection by its UV camera. But as with the atmospheric holes found in the Dynamic Explorer-1 images, those found in the Polar spacecraft's images also show a greater number of impacts during the morning hours as compared to the evening hours. This provides yet further confirmation that the holes are indeed real and not instrumental artifacts. If the holes were an artifact, then their appearance in the images should not be dependent on the time of day. Figure 1

. The need for this ultimate test of the reality of atmospheric holes arose after the presentation of the Polar small comet discoveries by University of Iowa researchers in May of 1997. Despite all the evidence presented from Polar proving that the atmospheric holes are indeed a geophysical phenomenon, many members of the scientific community still refused to accept the reality of the atmospheric holes, no doubt because of the immense implications of such large fluxes of small comets in the vicinity of our planet. These doubters have relied on an alternative hypothesis, which Frank calls the Parks-Dessler-Cragin Hypothesis--after George Parks, Alexander Dessler and Bruce Cragin--which holds that the atmospheric hole phenomenon is an artifact of the UV cameras. But if the holes were instrument artifacts, then the number of darkened clusters of pixels in the images should not be affected by the altitude of the spacecraft.(See comparison chart.) Since the ultimate test by Frank and Sigwarth shows that the appearance of atmospheric holes in the images varies significantly by altitude, the atmospheric holes must be a genuine geophysical phenomenon. "The scientific community must now proceed toward evaluating their origins," notes Frank.

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