Earth, Moon, and Sun System

Question 1

Explain what creates day and night on Earth

Answer 1

The Earth is always spinning, taking 24 hours for a full rotation

• When the side of Earth you’re on faces the Sun, it’s daytime because the Sun’s light is shining on you.
• When your side of Earth spins away from the Sun, it’s nighttime because you’re in Earth’s shadow.

It’s like turning a flashlight on a ball — the part facing the light is bright, and the other side is dark.

Question 2

Explain what causes seasons

Answer 2

Key concept: the Earth orbits the sun on a tilt, causing different parts of the earth to receive different amounts of sunlight

• When your half of Earth (your hemisphere) is tilted toward the Sun, you get more sunlight and warmer weather. That’s summer!
• When your hemisphere is tilted away from the Sun, you get less sunlight and colder weather. That’s winter!
• In between, you have spring and fall, when the sunlight is more even.

Think of Earth as a globe tilted on its side. As it moves around the Sun, the top (North Hemisphere) and the bottom (South Hemisphere) take turns being closer to the Sun.
* When it’s summer in one hemisphere, it’s winter in the other. For example, when it’s summer in the U.S., it’s winter in Australia!

Question 3

Explain the different phases of the moon

Answer 3

Key concept: The Moon doesn’t make its own light; it reflects sunlight. As the Moon orbits Earth, we see different parts of the lit-up side, which is why it looks like it’s changing shape.

The Lunar Cycle
The Moon goes through a full cycle of phases in about 29.5 days, which is about a month. Here are the main phases:

• New Moon: The Moon is between Earth and the Sun. The side of the Moon facing us isn’t lit up, so we can’t see it.
• Waxing Crescent: A little bit of the Moon’s lit-up side starts to appear as a curved sliver. “Waxing” means it’s getting bigger.
• First Quarter: Half of the Moon is lit up. It looks like a half-circle.
  * Waxing Gibbous: Most of the Moon is lit up, but it’s not full yet.
• Full Moon: The whole side of the Moon facing Earth is lit up. It’s a big, bright circle in the sky.
• **Waning Gibbous: **After the full Moon, the lit-up part starts getting smaller. “Waning” means it’s shrinking.
• **Last Quarter: **Again, half of the Moon is lit up, but now it’s the opposite side compared to the first quarter.
• Waning Crescent: Only a small curved sliver of light is left before it goes back to a new Moon.