Astronomy and Cosmic Phenomena Quiz

Which is true about star formation?

• Stars formed during the first few seconds after the Big Bang began during a cosmological period called Inflation.

• Stars formed about 500 million years after the Big Bang when cold hydrogen gas began condensing into large masses due to gravitational attraction and this eventually led to nuclear fusion reactions.

• Stars formed when intensely hot plasma (a mix of free electrons and protons) created from the initial Big Bang aggregated under the force of gravity to form very large cohesive masses of intensity hot matter.

Where did the heavy elements found inside of your own body (e.g., carbon and nitrogen) get created?

• 50% of the heavy elements were created directly from the Big Bang and the other 50% were created later inside of stars or when stars exploded.

• 10% of the heavy elements were created directly from the Big Bang and about 90% were created later inside of stars or when stars exploded.

• 100% of the heavy elements were created inside of stars or when stars exploded.

• 100% of the heavy elements were created within blackholes that form when stars collapse.

How do we know that our own sun is made from the dust of a previously exploded star?

• We have observed the nearby nebula Helios-N1, and we determine from its present path that it once occupied the location of our current sun.

• We know that our sun is young, and we know that other young stars formed from the remains of older stars.

• The sun is composed of hydrogen along with a range of much heavier elements.

• Given the sun’s current motion within our galaxy, we can determine where it was located in the galaxy 4.5 billion years ago, and we can see the remains of an ancient nebula from which the sun was formed.

How was our moon formed?

• Material was ejected into space from massive volcanic activity in early earth history, and this material aggregated over a 500-million-year period to form the moon.

• Small planetesimals were captured by earth’s gravity, and these planetesimals slowly collided while in earth’s orbit over a 500-million-year period to form our moon.

• The Moon and Earth formed simultaneously from the same material.

• A mars-sized object hit the Earth, and the ejected material subsequently coalesced to form the moon.

If you were to scale the earth down to the size of a small beach ball (1/2 meter in diameter), how thick would the ocean be?

• 0.015 nanometers

• 0.15 millimeters

• 15.0 centimeters

If you were on a boat at 10S and 20W, which ocean would you be in?

• Atlantic

• Pacific

• Indian

• Southern

• Arctic

Which is true about the rigid outer crust of the earth?

• The rigid outer crust sits atop a sold upper mantle. A layer of ancient water that sits between the crust and upper mantle acts as a lubricant that allows the crust to slide over the mantle with almost no frictional resistance.

• The ridged outer crust is all roughly the same age (4.5 billion years).

• The ridged outer crust is composed of granite-like rock.

• The rigid crust floats on top of the underlying mantle and acts sort of like a cork floating on water.

• The rigid outer crust has a remarkably consistent thickness of roughly 4km.

What evidence led Alfred Wegener to confirm that the continents had drifted over geologic time?

• The careful observation that the coastlines on opposite sides of ocean basins had near perfect fits (e.g., South America and Africa).

• The radioactive-dating methods he used showed that continents on the opposite side of ocean basins were identical in age.

• Fossil and mineral belts on separate modern-day continents aligned when the continents were artificially moved into a single super-continent.

• He painstakingly measured the current movement of the continents and then backtracked that movement in reverse and showed the continents merged into a single large super continent known as Pangea.

• Magnetic anomalies at midocean ridges.

Why is the symmetric banding of magnetic anomalies along mid-ocean ridges considered to be strong evidence to seafloor spreading?

• Because seafloor spreading causes the earth’s magnetic field to reverse.

• Because magnetic anomalies are a proxy for the age of the rock, and when dated, they show the crust getting symmetrically older as you move away on either side of the mid-ocean ridge.

• Because positive and negative magnetic anomalies in the ocean crust cause the crust itself to be forced apart by the magnetic force to drive divergent plate motion.

How are continents moved around on earth over geologic time?

• Continents moved around the earth when new oceanic crust is formed and pushes laterally against continental crust.

• Continents move when whole tectonic plates that they are embedded within move.

• The force of gravity from the moon pulls more strongly on the larger continental crust and drags it through the thinner oceanic crust.

• New continental crust is made at new locations while old crust cools and becomes denser and sinks back into the mantle. Together this gives the illusion of actual motion.