Time-Variable Cratering Rates?
نویسندگان
چکیده
منابع مشابه
Time-variable cratering rates?
Using stepwise laser-heating methods, Culler et al. (1) determined the Ar/Ar formation ages of 155 lunar impact melt beads from a soil sampled during the Apollo 14 mission. Because relatively old ages of .3 billion years (Gy) and fairly young ages of ,0.4 Gy dominate, Culler et al. concluded that the cratering rate in the inner solar system decreased by a factor of 2 to 3 during the past 3 Gy a...
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This paper is a compilation by table, graph, and equation of impact cratering rates from Jupiter to Pluto. We use several independent constraints on the number of ecliptic comets. Together they imply that the impact rate on Jupiter by 1.5-km-diameter comets is currently Ṅ(d 1.5 km) 0.005 0.003 0.006 per annum. Other kinds of impactors are currently unimportant on most worlds at most sizes. The ...
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We exploit recent theoretical advances toward the origin and orbital evolution of comets and asteroids to obtain revised estimates for cratering rates in the jovian system. We find that most, probably more than 90%, of the craters on the Galilean satellites are caused by the impact of Jupiter-family comets (JFCs). These are comets with short periods, in generally low-inclination orbits, whose d...
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Giant impacts by comets and asteroids have probably had an important influence on terrestrial biological evolution. We know of around 180 high velocity impact craters on the Earth with ages up to 2400 Myr and diameters up to 300 km. Some studies have identified a periodicity in their age distribution, with periods ranging from 13 to 50 Myr. It has further been claimed that such periods may be c...
متن کاملImportance of Cratering Processes
The importance of impact processes on a planetary scale has been recognized only fairly recently, after it became evident that not only our Moon (FIG. 1), but all other bodies in the solar system with a solid surface are covered with meteorite impact craters (FIG. 2). Impact cratering is a highenergy event that occurs at more or less irregular intervals (although over long periods of time, an a...
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ژورنال
عنوان ژورنال: Science
سال: 2000
ISSN: 0036-8075,1095-9203
DOI: 10.1126/science.288.5474.2095a