Nebular Theory
What does the Nebular Theory describe?
The formation of the solar system from a spinning cloud of gas and dust about 4.6 billion years ago.
What is chemical fractionation?
The separation of materials within a planet based on density forms layers.
What is meant by the term 'bombardment'?
The period when planets were hit by leftover debris from solar system formation.
What is a scale factor?
The ratio between the real-life size of an object and its size in a model.
What page can you find solar system data on?
Page 2
During the first stage, what caused the early solar system to flatten into a disk?
Spinning
During the Hadean Eon, what process allowed scientists to date ancient rocks?
Radiometric dating using uranium-to-lead decay.
Why do the Moon and Mars have more visible craters than Earth?
Earth’s atmosphere, weathering, erosion, and tectonic activity erase craters.
In a model, what does 1 meter equal to 1.5 million kilometers represent?
A scale factor used to model distances between planets.
What is the density of the mantle?
3.4-5.6 g/cm^3
What formed at the center of the spinning nebula?
The sun.
What mineral provides evidence of Earth's earliest history?
Zircon.
What term describes the depressions formed by impacts?
Impact craters
Which variable can be accurately represented in a model of the solar system: distances or diameters?
Usually one, not both—distance or size—because their scale differences are too large.
In what ERA did the Devonian Period occur?
Paleozoic Era.
What evidence supports the Nebular Theory today?
Observations of other star systems forming disks of gas and dust around young stars.
What do 'parent' and 'daughter' isotopes tell scientists about a rock?
The ratio reveals the rock's age.
Why do planets with more tectonic activity have fewer visible craters?
New crust replaces older, cratered surfaces.
What force caused planets to form spherical shapes during their formation?
Gravity pulling matter toward the center.
What is the parent isotope that has a half-life of 1.3 billion years?
Potassium-40 (K40)
Why do scientists use models to study the solar system's formation?
Because geological processes, such as erosion and plate tectonics, destroy direct evidence from early Earth.
Think Zircons
What do scientists notice about the absolute age of materials in our solar system?
Meteorites, lunar rocks, and Earth's oldest rocks all date to around 4.6 billion years ago.
What evidence shows that bombardment has decreased since the early solar system?
Younger surfaces, like Earth's, have fewer craters than older ones, like the Moon's.
Why is understanding planetary scale important in space science?
It helps visualize the immense distances and size differences in the solar system.
If 4.6 billion years have passed, how many half-lives of potassium-40 have occurred?
3 half-lives
4.6/1.3\approx 3.5