Astronomy Test 1

What causes seasons on Earth?

The tilt of Earth's spin axis.

How does sunlight affect summer temperatures?

In summer, days are longer, sunlight is more direct, and there is less atmosphere in the way.

What is cratering an indication of?

Surface age of planetary bodies.

What is surface dating based on?

Radioactive dating from rocks/core samples and cratering.

What determines the thickness of an atmosphere?

Escape velocity of the object, mass of gas particles, and temperature.

Characteristics of the terrestrial planets?

Solid surfaces with thin atmospheres, thin brittle crust, mantle, core, few moons, and density roughly 5 g/cc.

How is Mercury's atmosphere described?

Extremely thin and evaporative.

What unique feature does Venus have?

A thick 95% CO2 atmosphere and spins retrograde.

Mars' northern hemisphere is known for what?

Younger, lower altitude that may have contained an ocean.

What type of atmosphere does Europa have?

Very thin oxygen atmosphere.

What defines Jupiter's structure?

A cloudy atmosphere turning into a liquid, with a core of rock and a middle of liquid metallic hydrogen.

How many moons does Jupiter have and what are they primarily?

Over 60 moons, mostly captured asteroids.

What is unique about Titan?

It has a nitrogen atmosphere and shows features similar to Earth.

What are the components of Saturn's moon Enceladus?

Partially old surface, partially young surface with water geysers.

What is the composition of Neptunian planets?

Mostly hydrogen and helium atmosphere, with a liquid/solid water/ammonia/methane mantle and rocky core.

What is the density range for rocky terrestrial bodies?

Near 5 g/cc.

What are planetesimals?

Pre-planets that are moon-sized formed from colliding boulders.

What happens when a star 'turns on'?

It blows away any remaining gas back into the galaxy.

What are the steps of the scientific method?

Make an observation, create a theory, make predictions, test predictions, confirm/modify/refute the theory.