an error occurred while processing this directive] . Site Map . ... Timeline . ... Magnetic Field . ... Aurora . ... 3a. Loomis Aurora . 3b. Fritz Aurora . ... Hermann Fritz . Shown here is a map of the frequency with which auroras are seen, produced in 1881 by the German scientist Hermann Fritz (1830-1883). The line of greatest frequency lists 100 auroras per year, while in the center of the pattern auroras are much less frequent. ... Timeline Expanded timeline Glossary . ...

... The Magnetic Sun . ... Galileo had guessed they were clouds floating in the Sun's atmosphere, obscuring some of its light. ... It turned out that the Sun has a polar field somewhat like the Earth's, but that it reverses its polarity during each 11-year cycle. ... Sunspot fields were evidently produced by electric currents, and it was well known that such currents could be generated by a " dynamo process ," by the motion of an electric conductor (e.g. the flow of solar plasma) through a magnetic...

Educator's Guide to Impact Craters . ... Just about all craters have deep central depressions, raised rims, and a blanket of ejected material surrounding them. ... Look for classical cratering features: basin, raised rim, ejecta blanket (material excavated from the crater and dumped around it, visible as white flour on the colored powder), and rays (material shot out at high velocity forming lines pointing directly away from the impact site). ... The material lies like a blanket around the crater. ...

Cosmic Research, Vol. 42, No. 5, 2004, pp. 435­488. Translated from Kosmicheskie Issledovaniya, Vol. 42, No. 5, 2004, pp. 453­508. Original Russian Text Copyright © 2004 by Veselovsky, Panasyuk, Avdyushin, Bazilevskaya, Belov, Bogachev, Bogod, Bogomolov, Bothmer, Boyarchuk, Vashenyuk, Vlasov, Gnezdilov, Gorgutsa, Grechnev, Denisov, Dmitriev, Dryer, Yermolaev, Eroshenko, Zherebtsov, Zhitnik, Zhukov, Zastenker, Zelenyi, Zeldovich, Ivanov-Kholodnyi, Ignat'ev, Ishkov, Kolomiytsev, Krasheninnikov, Kudela,