What is Space?
Space is the vast, nearly empty area beyond Earth’s atmosphere. It contains stars, planets,
moons, asteroids, comets, gas, dust, and galaxies. Space has no air, so sound cannot travel,
and temperatures can be extremely hot or cold.
The Universe
The universe includes everything that exists: all space, time, matter, and energy. It began with
the Big Bang, which happened about 13.8 billion years ago.
Galaxies
Galaxies are huge systems made of stars, planets, gas, and dust held together by gravity.
Our galaxy is called the Milky Way
There are billions of galaxies in the universe
Stars
Stars are massive balls of hot gas (mostly hydrogen and helium) that produce light and heat
through nuclear reactions.
The Sun is a star
Stars have life cycles: birth, main sequence, and death (supernova, white dwarf,
neutron star, or black hole)
The Solar System
The solar system consists of the Sun and all objects that orbit it.
8 planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Other objects: moons, asteroids, comets, dwarf planets (e.g., Pluto)
Planets
Inner planets: Mercury, Venus, Earth, Mars (rocky)
Outer planets: Jupiter, Saturn, Uranus, Neptune (gas and ice giants)
Earth is the only known planet with life
Moons
Moons are natural satellites that orbit planets.
Earth has one moon
Some planets have dozens of moons
Asteroids and Comets
Space is the vast, nearly empty area beyond Earth’s atmosphere. It contains stars, planets,
moons, asteroids, comets, gas, dust, and galaxies. Space has no air, so sound cannot travel,
and temperatures can be extremely hot or cold.
The Universe
The universe includes everything that exists: all space, time, matter, and energy. It began with
the Big Bang, which happened about 13.8 billion years ago.
Galaxies
Galaxies are huge systems made of stars, planets, gas, and dust held together by gravity.
Our galaxy is called the Milky Way
There are billions of galaxies in the universe
Stars
Stars are massive balls of hot gas (mostly hydrogen and helium) that produce light and heat
through nuclear reactions.
The Sun is a star
Stars have life cycles: birth, main sequence, and death (supernova, white dwarf,
neutron star, or black hole)
The Solar System
The solar system consists of the Sun and all objects that orbit it.
8 planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Other objects: moons, asteroids, comets, dwarf planets (e.g., Pluto)
Planets
Inner planets: Mercury, Venus, Earth, Mars (rocky)
Outer planets: Jupiter, Saturn, Uranus, Neptune (gas and ice giants)
Earth is the only known planet with life
Moons
Moons are natural satellites that orbit planets.
Earth has one moon
Some planets have dozens of moons
Asteroids and Comets
