Sun, Moon, and Stars
Grade 2 · Science · Study Guide
Look up at the sky — day or night! Learn about the Sun, Moon, and stars and why they seem to move across the sky.
The Sun is a star — a giant ball of burning gas that gives Earth heat and light. Even though it looks small in the sky, the Sun is so big that about 1 million Earths could fit inside it! The Sun rises in the east every morning and sets in the west every evening. This happens because Earth spins around like a top — we call one full spin a day (24 hours).
The Moon is Earth's natural satellite. It orbits (travels around) Earth about once every 28 days. The Moon does not make its own light — it reflects sunlight, which is why we can see it! The Moon appears to change shape over the month — these are called phases. The phases go from a new moon (invisible) to a full moon (full circle) and back.
Stars are huge balls of burning gas like our Sun, but they are incredibly far away so they look tiny. On a clear night you can see thousands of stars! Groups of stars that form patterns in the sky are called constellations. Ancient people used constellations to navigate and tell stories. The North Star (Polaris) is a special star that always points north!
| Phase | What It Looks Like |
|---|---|
| New Moon | Not visible — dark |
| Crescent Moon | Thin curved sliver |
| Half Moon (Quarter) | Half circle lit up |
| Gibbous Moon | More than half lit |
| Full Moon | Complete circle of light |
Key terms
- Sun
- The star at the center of our solar system that provides heat and light
- Moon
- Earth's natural satellite that orbits Earth every 28 days
- star
- A giant ball of burning gas that produces light and heat
- orbit
- To travel around another object in space
- phases of the Moon
- The changing shapes the Moon appears to have during its monthly cycle
- constellation
- A group of stars that form a pattern or picture in the night sky
Flashcards
- Sun
- A star — a giant ball of burning gas — at the center of our solar system
- Moon
- Earth's natural satellite that orbits Earth about every 28 days
- Star
- A massive ball of burning gas that produces light and heat
- Orbit
- To travel in a path around another object in space
- Moon phases
- The changing appearances of the Moon over 28 days: new, crescent, half, gibbous, full
- Constellation
- A group of stars forming a recognizable pattern in the night sky
Practice questions
What is the Sun?
- A planet
- A moon
- A star
- A comet
Show answer
Answer: A star
The Sun is a star — a massive, glowing ball of plasma and gas that provides Earth with heat and light.
The Moon makes its own light like the Sun does.
Show answer
Answer: False
The Moon does not produce its own light. It reflects sunlight, which is why it glows in the night sky.
A group of stars that forms a pattern in the sky is called a ___.
Show answer
Answer: constellation
Constellations are patterns of stars in the sky. Examples include Orion, Ursa Major (Big Dipper), and Cassiopeia.
How long does it take the Moon to orbit Earth?
- 1 day
- 1 week
- About 28 days
- 1 year
Show answer
Answer: About 28 days
The Moon completes one full orbit of Earth approximately every 28 days, which is about one month.
Earth spinning causes the Sun to appear to rise in the east and set in the west.
Show answer
Answer: True
Earth rotates (spins) on its axis once every 24 hours. This spinning makes the Sun appear to rise in the east in the morning and set in the west in the evening.
Fun facts
- The Sun is so far from Earth (about 93 million miles) that its light takes about 8 minutes to reach us!
- Footprints left by astronauts on the Moon in 1969 are still there — there is no wind on the Moon to blow them away!
- The Big Dipper is part of a constellation called Ursa Major, which means 'Great Bear' in Latin!
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