Week 2 Astronomy Content Questions

Explain how you determine the age of rocks by radioactivity . Give an example

Each radioactive element decays at its own nearly constant rate , and once this is known , geologists can determine the length of time over which the decay has been occurring through measuring the amount of radioactive parent element and the amount of stable daughter elements (Mc Connel , 2001 . Potassium (K ) is particularly abundant in lava . In a volcanic eruption lava contains some K-40 and Ar-40 , a gas released when lava melts . As it solidifies the K-40 starts to decay into new

Ar-40 trapped into the rock . After 1 .25 billion years , half of the K-40 has been converted to Ar-40 so scientists could determine how long ago the rock was lava , allowing rock dating from a million to a few billion years (Mc Connel , 2001

How can scientists determine the internal structure of the Earth if the depth of the deepest well is only a tiny fraction of the Earth 's diameter

Scientific theories on the internal structure of the earth comes from studying data of how seismic waves travel through the earth , and how long it takes them to travel from their origin to the recording station on the premise that different materials transmit seismic waves at different speeds (Mc Connel , 2001

Impact cratering , volcanism , tectonics , and erosion are the four major processes that affect planetary surfaces . Briefly explain two

Impact cratering by extraterrestrial bodies is an important geological process . Heat generated by the early impacts may have led to the outgassing of the planet 's initial crust , thereby contributing to the creation of a primordial atmosphere and hydrosphere , even to the planet 's storage of volatiles (Mc Connel , 2001 . This early bombardment may have frustrated the development and evolution of early life , as asteroids and meteors upon impact often resulted in craters of varying sizes , some even capable of sterilizing the face of the earth . However most of the terrestrial impact craters have been obliterated by other geological processes , e .g . plate tectonics

Based on Plate Tectonics theory , the earth 's surface as composed of interlocking internally rigid plates (except at plate boundaries where tectonic activity is most common , are in constant motion with respect to each other as it is constantly being subjected to stress from the heat and pressure beneath the surface . Processes in plate tectonics include one that forms the physical earth and the other which occurs at the surface through weathering and erosion , with tectonics manifested by the processes of volcanism , earthquakes and mountain-building (Mc Connel , 2001

If the ages of the Earth and Moon are nearly identical , as believed , why are most rocks found on the Moon so much older than Earth rocks

Due to the absence of an atmosphere , volcanism and water on the Moon , it is considered geologically dead and fossilized in time due to its actively early history of bombardment , followed by a relatively abrupt end to such heavy impact activity (Mc Connel , 2001 . Components in its soils...