Unit 3 Study Guide

Which planets are shown in the image?

• Inner Planets

• Outer Planets

Answer explanation

The question asks about the planets shown. The correct answer is 'Outer Planets' because these include Jupiter, Saturn, Uranus, and Neptune, which are located beyond the asteroid belt, unlike the Inner Planets.

Which of the following is a mammal?

• Shark

• Dolphin

• Crocodile

• Eagle

Answer explanation

Dolphins are mammals because they give live birth, nurse their young with milk, and are warm-blooded. In contrast, sharks are fish, crocodiles are reptiles, and eagles are birds.

Pluto is not a planet anymore because it wasn't able to check this requirement. Mark only one oval.

• It must orbit a star (in our cosmic neighborhood, the Sun).

• It must be big enough to have enough gravity to force it into a spherical shape.

• Its gravity has cleared away any other objects of a similar size near its orbit.

Answer explanation

Pluto is classified as a dwarf planet because it has not cleared its orbit of other objects. This means it does not meet the requirement that its gravity must clear away similar-sized objects near its orbit.

Why does Neptune take 165 years to orbit the sun?

• The bigger planets have more mass.

• The closer a planet is to the sun, the more gravitational force it experiences.

• The smaller planets have less mass.

• The farther a planet is from the sun, the less gravitational force it experiences.

Answer explanation

Neptune takes 165 years to orbit the sun because it is far from the sun, resulting in less gravitational force acting on it. This lower gravitational pull means it moves more slowly in its orbit compared to closer planets.

In the Northern Hemisphere, which month receives indirect sunlight? Mark only one oval.

• December

• March

• June

• September

Answer explanation

In December, the Northern Hemisphere is tilted away from the sun, resulting in indirect sunlight and shorter days. This is why December is the correct answer for the month receiving indirect sunlight.

The Earth is tilted by ____ degrees.

• 23.5

• 20

• 70

• 55

Answer explanation

The Earth is tilted at an angle of approximately 23.5 degrees. This tilt is responsible for the changing seasons as it affects the angle and intensity of sunlight received at different latitudes.

Galaxies are composed of (best answer)

• stars
• stars and gas
• stars, dust, and gas
• stars, dust, and gas held together by gravity

In the Southern Hemisphere, which month receives direct sunlight? Mark only one oval.

• December

• March

• June

• September

Answer explanation

In the Southern Hemisphere, December is summer, and the sun is directly overhead at noon. This results in the most direct sunlight during this month, making it the correct choice.

Typically, a "Leap Year" occurs every?

• 1 year

• 2 years

• 3 years

• 4 years

Answer explanation

A Leap Year occurs every 4 years to keep our calendar in alignment with the Earth's orbit around the Sun. This is why the correct answer is 4 Years.

Which has a higher frequency?

• visible light

• ultraviolet rays