Jupiter2U School
Chapter 01

1. The Sun, the Moon & the Stars

Kindergarten

Look up! In the daytime sky you see the Sun. At night you see the Moon and tiny twinkling stars. This chapter is about what those three things really are.

At a glance
Core ideaThe sky holds three very different things: the Sun, the Moon, and the stars.
Key termStar — a giant glowing ball of gas that makes its own light and heat.
You can…Sort sky objects into "makes its own light" versus "borrows light."
Watch outThe Moon does not glow — it only reflects the Sun's light.
01 · Theory

Three very different things in the sky

The Sun is a giant, glowing ball of hot gas called a star. It makes its own light and heat, the same way a campfire does, only far, far bigger. The Sun is why we have daylight and why we feel warm outside.

The Moon does not make its own light. It is a big grey rock that circles around the Earth. The Moon looks bright because it bounces sunlight back to our eyes, the way a mirror bounces light around a room.

The stars you see at night are also glowing balls like the Sun — they are suns too! They only look tiny because they are unimaginably far away.

A star (like the Sun)

  • Makes its own light and heat
  • A giant ball of glowing hot gas
  • Fuses hydrogen — burns like a cosmic fire
  • The Sun is our nearest star

A planet / moon (like the Moon)

  • Makes no light of its own
  • A rocky (or gassy) world, not on fire
  • Only shines by reflecting sunlight
  • Circles a star or a planet
02 · Explanation

Why the Sun looks huge and stars look tiny

The Sun and the stars are actually all the same kind of thing — giant balls of glowing gas. The Sun just looks enormous and bright because it is close to us, while every other star is so far away that even though many are bigger than the Sun, they shrink to tiny points of light.

Think of two campfires: one right next to you looks huge and warm, and one far across a field looks like a tiny orange dot. Same fire, different distance. That is exactly why the Sun rules the daytime sky and the stars are barely-there dots at night.

03 · Practical

Hands-on: sort the sky

Activity

With a grown-up, go outside at two different times: once in the daytime, and once after dark (from a safe window is fine).

  1. In the daytime, find the Sun's warmth on your skin — never look right at it — and notice you cannot see any stars, even though they're still there.
  2. At night, find the Moon if it is out. Does it look like a full circle, a half circle, or a sliver?
  3. Count how many stars you can spot in one patch of sky the size of your hand held out at arm's length.
  4. Sort what you saw into three groups: "makes its own light" (Sun, stars) and "borrows light" (Moon).

Answer: the Sun and every star make their own light; the Moon only reflects light that comes from the Sun.

04 · Q&A

Test your understanding

Is the Moon a star?

No. The Moon is a rock that travels around the Earth. It has no light of its own — it only looks bright because sunlight bounces off it, like light bouncing off a mirror.

Why can't we see stars during the day?

The stars are still there — they never go away! But the Sun is so much closer and so much brighter that its light fills the whole sky and hides the faint light of the far-away stars.

Is the Sun a planet or a star?

A star. The Sun makes its own light and heat by itself, which is exactly what a star does. Planets, like Earth, do not make their own light.

Why does the Moon look grey and not glowing like the Sun?

Because the Moon isn't glowing at all — it's a rocky ball, like a giant grey stone. What you see is simply sunlight reflecting off its dusty grey surface, the same way sunlight reflects off a grey sidewalk.

Concept mind map

How the ideas connect

Every key idea in this chapter, branching from the core concept — use it to see the whole picture at a glance.

Sun is a starMoon reflectslightStars are distantsunsDay skyNight skyNear vs farThe Sun, Moon and Stars
Infographic

The key facts, visualised

Sun
Our closest star; gives daytime light and warmth
Moon
Rock ball that shines by reflecting the Sun
Stars
Other suns, so far away they look like tiny dots
Solved examples

Worked problems, step by step

Follow each solution line by line, then try to reproduce it on paper before moving on.

Example 1Why does the Sun look bigger than the stars?

  1. The Sun is also a star
  2. It only looks huge because it is very close to us
  3. The other stars are enormously farther away

Example 2You see a bright object at night that is not twinkling. Is it more likely a star or the Moon?

  1. Stars are tiny points that twinkle
  2. The Moon is large, steady and much closer
Practice problem set

Now you try

Work each one out first, then tap to reveal the worked answer.

1What is the Sun?
The Sun is a star, the closest one to Earth.
2Does the Moon make its own light?
No. The Moon shines by reflecting sunlight.
3Why do stars look so small?
They are other suns, but so far away they appear as tiny dots.
4When do we usually see the Sun?
During the daytime.
5Name two things you can see in the night sky.
The Moon and the stars.
6Is the Sun bigger or smaller than most stars we see at night?
It is a normal star; it only looks bigger because it is much closer.