Galaxies & The Milky Way
What is a galaxy?
A group of stars, dust, and gas held together by gravity
How many planets are in our solar system?
8 planets
What is the star in our solar system called?
The Sun
Where do stars begin their life?
In a star-forming nebula.
A large object in space that gives off heat and light.
A star
What is the name of our galaxy?
The Milky Way
Name the four terrestrial (rocky) planets.
Mercury, Venus, Earth, Mars
What is an object that orbits a planet called?
A moon.
What do low-mass stars eventually become?
White dwarfs.
The name for the Sun and everything that orbits it.
The solar system
About how many galaxies do scientists think exist?
Over 100 billion
What event started the universe about 13.7 billion years ago?
The Big Bang
What happens when a massive star explodes?
Supernova
What do massive stars turn into after a supernova?
Either a neutron star or a black hole.
An object that has a regular orbit around a star.
A planet
The Milky Way is a type of what kind of galaxy?
Spiral galaxy.
Name two things in the solar system besides the planets.
moons, dwarf planets, asteroids, comets, meteors
A collection of billions of stars and their solar systems is called a ________.
Galaxy
About how long can red dwarfs live?
Hundreds of billions of years
Which planet is closest to the Sun?
Mercury
What type of galaxies has no defined shape?
Irregular galaxies
List the 8 planets in order starting from the Sun.
Mercury → Venus → Earth → Mars → Jupiter → Saturn → Uranus → Neptune
What is a galaxy made up of?
Billions of stars and solar systems.
What type of star ends as either a neutron star or a black hole?
Massive stars.
Which lives longer: a massive star or a low-mass star?
Low-mass star