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Grade 4 (age 9-10)

grade 4 Stars and Constellations

Stars and Constellations

A constellation is a pattern people imagined by joining the bright stars of the night sky. The ladle-shaped Big Dipper points toward Polaris in the north, while W-shaped Cassiopeia shines all year. Stars differ in brightness: the brightest are called 1st magnitude, and stars just visible to the naked eye are 6th magnitude. Tap a constellation button and the stars and lines appear, so the brightness ranks can be compared.

Constellations in the Night Sky

✨ What is a Constellation?
①A pattern made by connecting bright stars
②Ancient people imagined and named them
③Different constellations appear by season
④Big Dipper helps locate the North Star

Star Brightness

💡 Star Brightness
①Each star has different brightness
②Magnitude 1 is brightest, 6 is dimmest
③Naked eye can see up to magnitude 6
④Stars have many colors (blue, white, yellow, red)
⑤Blue stars are the hottest

Summary

Constellation
Constellation = bright stars connected by lines
Visible constellations differ by season
Finding Polaris
Big Dipper end stars × 5 distances = Polaris
Polaris is always north — a direction guide
🎯 Key Points
①Constellations connect bright stars in patterns
②Big Dipper: ladle shape, find Polaris
③Cassiopeia: W shape, year-round
④Mag 1 brightest, mag 6 dimmest
⑤Star color depends on temperature (blue = hottest)

Examples and Unit Test

Example 1
Which is the brighter star, a first-magnitude star or a sixth-magnitude star?
1
Star brightness is shown by magnitude, and the smaller the number, the brighter the star.
2
A first-magnitude star has a small number, so it is brightest; a sixth-magnitude star is the faintest one visible to the naked eye.
▸ The first-magnitude star (smaller number = brighter)
For star magnitude, a smaller number means a brighter star.
Example 2
How can you use the Big Dipper to find the star that shows direction?
1
The Big Dipper is a ladle-shaped constellation that guides you to the North Star.
2
The North Star sits about five times the gap between the two end stars of the dipper, extended outward.
▸ Five times the gap between the two end stars of the dipper → the North Star
The North Star is always in the north, so it shows direction.
Unit-test style
Which statement about stars and constellations is correct?
①A sixth-magnitude star is brighter than a first-magnitude star
②The North Star is always in the north, so it shows direction
③Constellations look exactly the same even as seasons change
④All stars are the same color
⑤A constellation is a cluster of stars that are actually stuck together
▸ ② The North Star is always in the north, so it shows direction
1
The North Star is always in the northern sky, so it helps you find direction.
2
A first-magnitude star is brighter than a sixth-magnitude one (①), different constellations appear by season (③), star colors vary with temperature (④), and a constellation is just a picture made by joining distant stars (⑤).
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