The Solar System - Recap & Expand Video

What percentage of the solar system's total mass does the Sun comprise?

• less than 50%

• approximately 75%

• exactly 90%

• more than 98%

Which ancient model of the universe placed Earth at its center?

• Heliocentric model

• Geocentric model

• Copernican model

• Keplerian model

What shape did Johannes Kepler discover planets orbit the Sun in?

• Perfect circles

• Ellipses

• Spirals

• Irregular paths

Why is it difficult to create a rigid definition for what constitutes a "planet"?

• Planets are constantly changing their physical properties.

• There are too many exceptions to any proposed definition.

• Scientists have not yet explored enough celestial bodies.

• The term "planet" is a relatively new concept.

What is a key difference between objects in the Kuiper Belt and objects in the Oort Cloud?

• Kuiper Belt objects are spherical, while Oort Cloud objects are disc-shaped.

• Kuiper Belt objects orbit in the same plane as the planets, while Oort Cloud objects orbit in all directions.

• Oort Cloud objects are larger than Kuiper Belt objects.

• Kuiper Belt objects are primarily made of gas, while Oort Cloud objects are primarily made of ice.

What event is believed to have initiated the collapse of the balanced cloud that eventually formed our solar system?

• A sudden increase in the cloud's internal heat.

• The gravitational pull of a newly formed star within the cloud.

• A shockwave from an exploding star or a passing cloud.

• A decrease in the cloud's overall mass.

Why did the collapsing cloud flatten into a disk as it formed the solar system?

• The intense heat from the forming Sun pushed material outwards.

• The conservation of angular momentum caused it to spin faster and flatten.

• Collisions between dust grains forced the cloud into a flat shape.

• The magnetic fields within the cloud aligned the material into a disk.

What is the primary reason inner planets are rocky and outer planets are gas giants?

• Inner planets formed from heavier elements, while outer planets formed from lighter elements.

• The Sun's heat prevented lighter gases from accumulating on inner planets, while outer planets were cool enough to retain them.

• Inner planets experienced more collisions, stripping away their gaseous atmospheres.

• Outer planets had stronger magnetic fields that attracted more gas.