Astronomy: Stars, Galaxies, and the Universe
Exploring objects and patterns in space
Astronomy: Stars, Galaxies, and the Universe
Exploring objects and patterns in space
Earth Science - Grade 6-8
- 1
What is a star, and how is it different from a planet?
Think about which object gives off light and which one reflects it.
A star is a large ball of hot gas that produces its own light and energy. A planet does not make its own light and usually orbits a star. - 2
The Sun is classified as a star. Explain why the Sun is important to Earth.
The Sun is important because it provides Earth with light and heat. It also supplies the energy that supports weather, climate, and life. - 3
Describe one way stars can appear different from each other when viewed from Earth.
You might describe brightness, color, or size.
Stars can appear different in brightness, color, and size. These differences can be caused by their temperature, distance from Earth, and actual size. - 4
What is a galaxy?
A galaxy is a huge collection of stars, gas, dust, and other objects held together by gravity. Galaxies can contain billions of stars. - 5
What galaxy contains our solar system?
It has a name related to a white band seen in the night sky.
Our solar system is in the Milky Way galaxy. The Milky Way is a large spiral galaxy. - 6
Name one type of galaxy and describe its general shape.
One type of galaxy is a spiral galaxy, which has a flat disk with curved arms. Other correct examples include elliptical galaxies, which are round or oval, and irregular galaxies, which have no clear shape. - 7
How does gravity help form stars and galaxies?
Focus on how matter moves and stays together.
Gravity pulls gas and dust together into clumps. Over time, this pulling can help form stars, and gravity also holds galaxies together. - 8
A light-year is used in astronomy. What does a light-year measure?
A light-year measures distance, not time. It is the distance light travels in one year. - 9
Why do astronomers often say looking far into space is also looking into the past?
Think about how fast light travels and how far away galaxies are.
Astronomers say this because light takes time to travel across space. When we see very distant objects, we are seeing the light they gave off long ago. - 10
What is the universe?
The universe is everything that exists, including all matter, energy, space, time, stars, planets, and galaxies. It includes all of the objects and regions we can detect and more beyond that. - 11
Many scientists say the universe is expanding. What does this mean?
Think about the distance between galaxies changing.
An expanding universe means that, on a large scale, galaxies are moving farther apart over time. It does not mean every object is growing in size. - 12
Explain the difference between the solar system, the Milky Way galaxy, and the universe.
The solar system includes the Sun and the objects that orbit it. The Milky Way galaxy contains the solar system and billions of other stars, and the universe contains all galaxies and everything in space.