• Journal of Astronomy and Space Sciences
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• v.25 no.2
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• pp.71-76
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• 2008

Study of terrestrial impact craters is important not only in the field of the solar system formation and evolution but also of the Galactic astronomy. The terrestrial impact cratering record recently has been examined, providing short- and intermediate-term periodicities, such as, ${\sim}26$ Myrs, ${\sim}37$ Myrs. The existence of such a periodicity has an implication in the Galactic dynamics, since the terrestrial impact cratering is usually interpreted as a result of the environmental variation during solar orbiting in the Galactic plane. The aim of this paper is to search for a long-term periodicity with a novel method since no attempt has been made so far in searching a long-term periodicity in this research field in spite of its great importance. We apply the cepstrum analysis method to the terrestrial impact cratering record for the first time. As a result of the analysis we have found noticeable peaks in the Fourier power spectrum appear ing at periods of ${\sim}300$ Myrs and ${\sim}100$ Myrs, which seem in a simple resonance with the revolution period of the Sun around the Galactic center. Finally we briefly discuss its implications and suggest theoretical study be pursued to explain such a long-term periodicity.

• Journal of Astronomy and Space Sciences
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• v.23 no.3
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• pp.199-208
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• 2006

The terrestrial impact cratering record recently has been examined in the time domain by Chang & Moon (2005). It was found that the ${\sim}26$ Myr periodicity in the impact cratering rate exists over the last ${\sim}250$ Myrs. Such a periodicity can be found regardless of the lower limit of the diameter up to D ${\sim}35km$. It immediately called pros and cons. The aim of this paper is two-fold: (1) to test if reported periodicities can be obtained with an independent method, (2) to see, as attempted earlier, if the phase is modulated. To achieve these goals we employ the time/frequency analysis and for the first time apply this method to the terrestrial impact cratering records. We have confirmed that without exceptions noticeable peaks appear around ${\sim}25$ Myr, corresponding to a frequency of ${\sim}0.04(Myr)^{-1}$. We also find periodicities in the data base including small impact craters, which are longer. Though the time/frequency analysis allows us to observe directly phase variations, we cannot find any indications of such changes. Instead, modes display slow variations of power in time. The time/frequency analysis shows a nonstationary behavior of the modes. The power can grow from just above the noise level and then decrease back to its initial level in a time of order of 10 Myrs.

• Publications of The Korean Astronomical Society
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• v.27 no.5
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• pp.411-418
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• 2012

We study the correlation between distributions of astronomical records and historical events using historical meteor (shower) records. In Korean chronicles, planets and meteor (shower) records are the most abundant astronomical phenomena. And they represent a general tendency of the number distribution of whole astronomical observations. We examine the correlation for the number distribution between meteors (showers) and planets during A.D. 1200-1700 and find that both records have a similar distribution. We classify historical events into three grades according to the social impact, and investigate the correlation between distributions of meteor (shower) records with social events, such as, new king's accession to the throne, foreign invasions, and domestic turmoils. From the statistical analysis, we cannot find any correlation between the meteor (shower) records and the political events. Therefore, we conclude that Korean historical records have not been influenced by the political events. We also examine the correlation between Chinese and Japanese meteor (shower) records and political events for A.D. 1200-1700, respectively, but cannot find any correlations between them.