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Special Topics in Planetary Science


FireballsFireballs that Produce Meteorites -Fireballs in the sky are caused by interplanetary debris crashing into Earth's atmosphere. Some fireballs result in showers of meteorites, rocks or metal that fall from the sky. This page follows an international team as they put these two phenomena together to learn the composition, structure, and paths of these objects.
Iredescent CloudsIridescent Clouds - Have you ever seen clouds near the sun shimmering with pearly colors? This effect is produced by a different optical process than the more familiar rainbow. This page helps you to see iridescent clouds yourself, and to understand what causes them.
Building Planets at PSIBuilding Planets at PSI - At PSI, theoretical computer models are used to investigate how the planets formed. This page shows how we can learn about the early history of our solar system by using physics to create computer models and comparing them with observations of the real solar system.
The Origin of the MoonThe Origin of the Moon - In 1975,two PSI scientists were first to suggest the leading modern hypothesis of the moon's origin. This page shows how the moon is believed to have formed, as well as showing the process of science, the formation and testing of a hypothesis, and the roles of observation and theory in advancing scientific knowledge.
Multi-ring impact basins on the MoonMulti-ring impact basins on the Moon: discoveries and early research papers - This web page makes available early, now-obscure discovery papers about lunar basins, first published in Gerard Kuiper’s journal series, Communications of the Lunar and Planetary Laboratory, and in an international journal, The Moon, which is now defunct. An introductory tutorial text gives an overview of multi-ring basins, their discovery and current research. Such basins, somewhat controversial at first, have now been recognized on most other large planetary worlds, from Mars and Mercury to various satellites. Commentary by William K. Hartmann.
Martian Cratering StudiesIntroduction to Martian Cratering Studies - By measuring the distribution of craters on the surface of a planet, much can be learned about the age of the surfaces, the volcanic and erosional processes occurring there, and even about the planet's atmosphere. This page is an introduction to cratering studies on the planet Mars.
Siberia ExplosionSiberia Explosion - In 1908,a large meteorite exploded over a remote area of Siberia. PSI scientist and artist William K. Hartmann used the eyewitness accounts of this event to attempt to reconstruct what happened and to create paintings showing what it may have looked like to observers. This page presents his results and explores the significance of asteroid impacts to our planet.
K-T Boundary ImpactThe KT-Boundary Impact -According to abundant geological evidence, an asteroid roughly six miles across hit the earth about 65 million years ago. The impact made a crater over 100 miles across, severely altering the climate of the whole planet and causing the extinction of three-fourths of the species then existing. This page explores what we know about this impact, how we know it, and the implications for future impacts.
CoronadoThe Coronado Expedition - In the 1530s and 1540s,the first European exploration of the American Southwest included a large expedition led by the Spanish explorer Coronado. This page describes the circumstances of the expedition, the route, the people who carried it out, and the archeological investigations that revealed the details and route of the expedition.
Crater "Greg"Martian Glaciers: A Photo-Tour of the Extraordinary Crater "Greg" - The north inner wall of this 66-km wide crater contains a concentration of lobate tongue-shaped features believed to be young Martian glaciers. The inner south wall has deposits also believed to represent ice flow. Greg lies east of the Hellas basin in a region known for ice-related features. Global climate models predict that this region gets the highest rate of ice deposition on Mars during periods of high axial tilt. Predicting features we can actually see on Mars indicates that planetary climate change modeling should be taken seriously.


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