Compare the planets, and where liquid water could exist

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Planets (NASA Planetary Fact Sheet)

   Planet	Distance (million km)	Mean temperature (°C)	Density (kg/m³)
   Mercury	57.9	167	5,429
   Venus	108.2	464	5,243
   Earth	149.6	15	5,514
   Mars	228.0	−65	3,934
   Jupiter	778.5	−110	1,326
   Saturn	1,432.0	−140	687

2. 1.

   How far is Mars from the Sun compared with Earth, by Bo's math?

   • About 0.66 times as far
   • The same distance
   • About 1.5 times as far
   • About 78 million km closer
3. 2.

   Water has a density of 1,000 kg/m³. Which planet in the table is less dense than water, by Jun's reading?

   • Saturn
   • Mars, the reddest planet
   • Each giant planet
   • Jupiter, at 1,326 kg/m³
4. 3.

   Habitable-zone distance grows as the square root of brightness; star 4 times the Sun's brightness. A star is 4 times as bright as the Sun. Since sunlight falls off with distance squared, how far out is its habitable zone compared with the Sun's, by Kira's math?

   • Half as far
   • The same distance
   • About twice as far
   • About 4 times as far
5. 4.

   Habitable-zone distance grows as the square root of brightness; star 1/100 of the Sun's brightness. A red dwarf gives off 1/100 of the Sun's light. Where is its habitable zone compared with the Sun's, by Luz's math?

   • At the same distance
   • About 10 times as far away
   • About one-tenth as far
   • About 1/100 as far
6. 5.

   NASA: TRAPPIST-1, about 40 light-years away, has seven rocky planets, and three (e, f and g) lie in its habitable zone. Which statement fits, by Milo's reading?

   • The zone is as far out as Earth's
   • The seven planets have oceans covering their surfaces
   • Liquid water could exist on e, f and g
   • Life lives on e, f and g

7. Diameters (NASA)

   Body	Diameter (km)
   Sun	1,391,400
   Jupiter	142,984
   Earth	12,756

8. 6.

   For a transit, the dip in starlight is (planet diameter ÷ star diameter)². Jupiter is 142,984 km wide; the Sun is 1,391,400 km. About how big is the dip, by Noah's math?

   • About 1%
   • About 100%
   • About 0.01%
   • About 10%
9. 7.

   Using the same rule and table, about how big is the dip for an Earth-sized planet crossing the Sun, by Pia's math?

   • About 9%
   • About 0.008%
   • About 0.9%
   • About 1%, like Jupiter
10. 8.

    Why are Earth-sized planets easier to find around small red dwarfs than around Sun-like stars, by Ren's reading (NASA)?

    • The dip is the same for any star
    • A small star loses a bigger share of its light
    • Red dwarfs are brighter than the Sun
    • Planets glow more near red dwarfs

11. Planets (NASA Planetary Fact Sheet)

    Planet	Distance (million km)	Mean temperature (°C)	Density (kg/m³)
    Mercury	57.9	167	5,429
    Venus	108.2	464	5,243
    Earth	149.6	15	5,514
    Mars	228.0	−65	3,934
    Jupiter	778.5	−110	1,326
    Saturn	1,432.0	−140	687

12. 9.

    Mercury is closer to the Sun, yet Venus is hotter. What does this show about judging a planet's temperature, by Tala's reading?

    • The table must be wrong
    • The atmosphere matters, not just the distance
    • Venus must be closer than Mercury
    • Distance decides it alone
13. 10.

    Earth sits in the Sun's habitable zone, and Venus lies inside its inner edge. Which statement fits, by Ari's reading?

    • Both have oceans, since both are near the zone
    • Earth's surface can hold liquid water; Venus is too hot
    • Venus is the cooler of the two
    • The zone is the same for any star