How many planets currently make up our Solar System?
A Eight
B Seven
C Nine
D Ten
The Solar System has eight recognized planets. Pluto is classified as a dwarf planet.
Which planet is nearest to the Sun?
A Mercury
B Venus
C Earth
D Mars
Mercury is the innermost planet in the Solar System.
Which planet has the greatest diameter in the Solar System?
A Saturn
B Neptune
C Earth
D Jupiter
Jupiter is the largest planet by both diameter and mass in our Solar System.
Which planet is famous for its broad, bright ring system?
A Saturn
B Mars
C Mercury
D Venus
Saturn’s rings are made mostly of pieces of ice and rock.
What is the Moon in relation to Earth?
A Dwarf planet
B Natural satellite
C Comet
D Star
The Moon is Earth’s natural satellite because it orbits Earth.
What do astronomers call the path followed by an orbiting body?
A Orbit
B Axis
C Spectrum
D Crater
An orbit is the path an object follows around another object because of gravity.
Most planetary paths around the Sun are close to which shape?
A Square
B Triangle
C Ellipse
D Perfect line
Planetary orbits are ellipses, although many are nearly circular.
What is an apparent pattern of stars in the sky called?
A Galaxy
B Nebula
C Asteroid
D Constellation
A constellation is a named pattern or region of stars as seen from Earth.
Which instrument gathers light from distant space objects?
A Compass
B Microscope
C Barometer
D Telescope
A telescope collects light or other radiation so distant objects can be studied.
Why does the Moon look bright in our sky?
A It makes its own light
B It burns like a star
C It reflects sunlight
D It reflects Earth’s core
The Moon does not make visible light like a star; it reflects sunlight.
Which two gases make up most of the Sun?
A Hydrogen and helium
B Oxygen and nitrogen
C Carbon and oxygen
D Iron and neon
The Sun is made mostly of hydrogen and helium.
Where is the main asteroid belt located?
A Between Earth and Mars
B Beyond Neptune
C Between Venus and Earth
D Between Mars and Jupiter
Most main-belt asteroids orbit the Sun between Mars and Jupiter.
What is an asteroid mainly?
A A glowing star
B A gas planet
C A rocky space body
D A cloud on Earth
Asteroids are small rocky or metallic bodies that orbit the Sun.
Which material is common in comets?
A Liquid water only
B Ice and dust
C Pure iron
D Hot plasma only
Comets contain ice, dust, and rocky material; sunlight can make their ice release gas.
What is the bright streak produced when a meteoroid enters Earth’s atmosphere?
A Meteorite
B Asteroid
C Comet
D Meteor
A meteor is the visible streak of light made as a space rock moves through the atmosphere.
What is a space rock called if part of it reaches the ground?
A Meteor
B Nebula
C Meteorite
D Satellite
A surviving piece that reaches the ground is called a meteorite.
Which star is at the center of our Solar System?
A Sirius
B Polaris
C Sun
D Proxima Centauri
The Sun is the star at the center of the Solar System.
Which planet is farthest from the Sun among the eight planets?
A Uranus
B Saturn
C Neptune
D Jupiter
Neptune is the outermost of the eight recognized planets.
What does the word “solar” mean?
A Related to the Sun
B Related to the Moon
C Related to Earth
D Related to stars generally
Solar means relating to the Sun.
What is a group of stars held together by gravity called?
A Solar flare
B Star cluster
C Planetary ring
D Meteor shower
A star cluster is a group of stars held together by their mutual gravity.
What is a robotic spacecraft sent to investigate a distant world often called?
A Weather balloon
B Space probe
C Space elevator
D Ground station
A space probe travels to collect information about a celestial body or region of space.
What best describes the International Space Station?
A An orbiting research laboratory
B A telescope on the Moon
C A probe on Mars
D A permanent base on the Sun
The International Space Station is a crewed laboratory that orbits Earth.
What is a small rocky body in space called before it enters an atmosphere?
A Meteor
B Meteoroid
C Meteorite
D Moon
A meteoroid is a small rocky or metallic body in space; the name changes if it enters an atmosphere.
Which planet often looks reddish because of iron-rich dust on its surface?
A Venus
B Uranus
C Neptune
D Mars
Iron-rich minerals in Martian soil give Mars its familiar reddish appearance.
Which planet rotates with its axis tipped almost onto its side?
A Jupiter
B Uranus
C Mercury
D Mars
Uranus has an extreme axial tilt, so it rotates nearly on its side.
What is the visible surface layer of the Sun called?
A Core
B Corona
C Photosphere
D Chromosphere
The photosphere is the layer from which most of the Sun’s visible light escapes.
What is a large system of stars, gas, and dust held together by gravity called?
A Constellation
B Galaxy
C Solar system
D Meteor group
A galaxy is a vast system containing stars, gas, dust, and other matter bound by gravity.
What is a human-built object placed in orbit around Earth called?
A Natural moon
B Comet
C Artificial satellite
D Meteorite
An artificial satellite is made by people and placed into orbit around Earth or another body.
Why do we see light from a distant star as it was in the past?
A Light takes time to reach us
B Stars move backward in time
C Earth stops rotating
D Telescopes slow the light
Light travels at a finite speed, so it takes time to reach us from distant stars.
About how long does Earth take to complete one orbit around the Sun?
A One day
B One month
C Ten years
D One year
One complete Earth orbit around the Sun takes about one year.