Space Basics
What do we call the vast, mostly empty area beyond Earth that contains planets, stars, and galaxies?
Outer space.
At about how many miles above Earth does space begin?
About 62 miles above Earth.
What is at the center of our solar system?
The Sun.
What are the two main ways Earth moves?
Rotation and revolution.
What is the Moon and how long does it take to orbit Earth once?
A rocky object that orbits Earth; about 29 days.
Name three things found in outer space.
Planets, stars, galaxies (any three: planets, stars, galaxies, asteroids, comets, etc.).
What unit is used for distances within our solar system and what does 1 of these equal?
Astronomical Unit (AU); 1 AU ≈ distance from Earth to the Sun (about 150 million kilometers).
Name the eight planets in order from closest to farthest from the Sun.
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
How long does it take Earth to rotate once and what does rotation cause?
24 hours; causes day and night.
Why does the Moon appear to change shape (phases)?
The Moon’s phases are caused by the changing positions of the Sun, Earth, and Moon which change how much of the lit side we see.
Why do space telescopes give clearer images than telescopes on Earth?
Because they orbit outside Earth’s atmosphere, so there is no atmospheric distortion.
What does a light year measure and is it a measure of distance or time?
A light year measures distance — the distance light travels in one year.
What is gravity and why does it keep planets in orbit?
Gravity is the force that pulls objects toward each other; the Sun’s gravity pulls planets into curved paths (orbits).
How long does it take Earth to revolve around the Sun?
365 days (one year)
What are the names of the New Moon and Full Moon (what do they look like)?
New Moon = not visible (the lit side faces away from Earth). Full Moon = fully lit and visible.
What is a satellite and give two uses of satellites on Earth.
A satellite is an object that orbits Earth. Uses: communication, weather monitoring, GPS, studying space.
Approximately how many miles does light travel in one year (in simple terms used in the study guide)?
About 6 trillion miles (or ~10 trillion kilometers) in one year (approximate values from guide).
How would your weight change on a much larger planet like Jupiter compared to on Mars, and why?
On Jupiter you would feel heavier because Jupiter has more mass and stronger gravity; on Mars you would feel lighter because it has less mass and weaker gravity.
What causes the seasons on Earth? Give two factors
Earth’s tilt and Earth’s orbit around the Sun.
What causes stars to shine (name the process and the two main elements involved)?
Nuclear fusion; hydrogen fuses into helium, releasing light and heat
What is an observatory and why are many observatories built on high mountains?
An observatory is a building with powerful telescopes used to study space; mountains reduce atmospheric distortion and light pollution.
Which unit would scientists use to measure the distance to the Andromeda Galaxy and about how many of those units away is it?
Light years; Andromeda ≈ 2.5 million light years away.
Describe what a solar system is and name at least three types of objects (other than planets) found in it.
A solar system is a star and all objects orbiting it; includes moons, asteroids, comets, dwarf planets, dust and rocks.
Explain why when Earth is tilted toward the Sun it is summer in that hemisphere (use direct sunlight and day length).
When tilted toward the Sun the hemisphere receives more direct sunlight and has longer daylight hours, so temperatures are warmer (summer).
Explain apparent brightness and list two things that affect how bright a star looks from Earth.
Apparent brightness is how bright a star looks from Earth; affected by the star’s distance and the star’s size (or intrinsic brightness).