Planets
The planet closest to the Sun.
What is Mercury?
What type of object is the Sun?
A star.
What force keeps planets in orbit around the Sun?
Gravity
The galaxy that contains our solar system.
What is the Milky Way?
I am rocky.
I am the third planet from the Sun.
I have one natural satellite.
Who am I?
Earth
The largest planet in our solar system.
What is Jupiter?
Why does the Sun appear much larger and brighter than other stars?
It is much closer to Earth.
What object provides most of the gravitational pull that keeps the planets in their orbits?
The Sun
A huge collection of stars, gas, dust, and other matter held together by gravity.
What is a galaxy?
I am not a planet.
Planets orbit me.
I provide most of the gravitational pull controlling planetary orbits in our solar system.
Who am I?
The Sun
Put these planets in order from closest to farthest from the Sun: Mars, Venus, Mercury, Earth.
Mercury → Venus → Earth → Mars
Give two characteristics scientists can use to describe or compare stars.
True or false: There is no gravity in space. Explain your answer.
False. Gravity acts throughout space and is responsible for phenomena such as planets orbiting stars and moons orbiting planets.
Put these in order from smallest scale to largest scale:
Milky Way — Earth — Universe — Solar System
Earth → Solar System → Milky Way → Universe
A student created this model:
Earth → Milky Way → Solar System → Universe
They say it shows smallest to largest.
What is wrong with the model?
The Milky Way and solar system need to switch places.
Correct model:
Earth → Solar System → Milky Way → Universe
Give two differences between the inner planets and the outer planets.
inner planets are smaller, rocky, denser, closer to the Sun, have fewer moons, and lack rings; outer planets are larger gas/ice giants, farther from the Sun, have many moons, and have ring systems.
A student says, “The Sun must be the largest star because it looks larger than every other star in the sky.” What is wrong with this reasoning?
The Sun appears larger because it is much closer to Earth. Apparent size does not prove it is the largest star.
Why doesn't Earth simply fly away from the Sun as it moves through space?
The Sun's gravity continually pulls Earth toward the Sun, changing the direction of Earth's motion and keeping Earth in orbit.
Which statement is correct, and explain why?
A. The Milky Way is inside our solar system.
B. Our solar system is inside the Milky Way.
C. The Milky Way and solar system are the same thing.
D. Our solar system is larger than the Milky Way.
B. Our solar system is one small part of the Milky Way galaxy.
Which object doesn't belong with the others, and why?
Mercury — Venus — Earth — Jupiter
Jupiter. Mercury, Venus, and Earth are rocky inner planets; Jupiter is an outer gas giant.
A planet is large, has rings, has many moons, and is made mostly of gas. Would you expect to find this planet in the inner or outer solar system? Explain using two pieces of evidence.
Outer solar system. Large size, rings, many moons, and gaseous composition are characteristics of the outer planets.
Answer: No. How bright a star appears depends on both its actual luminosity and its distance from Earth.
Two stars appear equally bright from Earth. Can you conclude that they are the same distance from Earth? Explain.
No. How bright a star appears depends on both its actual luminosity and its distance from Earth.
Planet. Distance from Sun Time to Orbit Sun
A 58 million km 88 days
B 150 million km 365 days
C 228 million km 687 days
D 778 million km 4,333 days
What pattern do you notice between a planet's distance from the Sun and the amount of time it takes to orbit?
As distance from the Sun increases, orbital period generally increases. For example, A is only 58 million km away and takes 88 days, while D is 778 million km away and takes 4,333 days.
Object. Approximate Diameter
Earth 12,742 km
Jupiter 139,820 km
Sun 1,392,700 km
Approximately how many Earth diameters would fit across the diameter of the Sun?
A. 11
B. 50
C. 109
D. 1,000
C — approximately 109 Earths.
A scientist-in-training writes:
“Earth orbits the Sun because Earth is the largest object in the solar system. Gravity only works on planets, so it does not affect stars or galaxies.”
Identify TWO scientific errors and correct them.