Planets and the Solar System

There are perhaps thousands of galaxies in the universe.

Galaxies contain planets moons comets meteors asteroids

All these objects spin or orbit around a center star, our sun.

sun

Solar flare

Our galaxy, the Milky Way, orbits around the sun.

3 main galaxy shapes elliptical irregular spiral

elliptical galaxy

irregular galaxy

spiral galaxy

The Milky Way is a spiral galaxy.

There are thousands of galaxies, other than ours, in the universe There are thousands of galaxies, other than ours, in the universe. Some are very likely able to support life.

There are eight known planets.

The planets are divided into two main groups: inner and outer

inner planets Mercury Venus Earth Mars

Mercury

Venus

Venus

Venus

Venus fires

Mars

Mars

Mars

Olympia Mont on Mars Olympia Mont on Mars

Ice found on Mars!

The inner planets are smaller and made of rock and iron.

outer planets Jupiter Saturn Uranus Neptune

Shoemaker-Levy comet pieces that hit Jupiter

Shoemaker-Levy comet strikes (time lapsed)

Jupiter’s Big Red Spot

Jupiter

Jupiter and moons

Look how small the moon Io is compared to Jupiter. Our moon is 1/4 our size!

Callisto-Jupiter’s moon

Ganymede - Jupiter moon

Saturn

Saturn family

Neptune and moons

Neptune’s great dark spot

Neptune’s clouds

Uranus

The outer planets are larger and made of hydrogen, helium, and ice.

STARS

Stars are classified by their different temperatures, which cause them to be different colors.

star classifications red yellow bluish white

Stars are born from a cloud of gas and dust.

interstellar dust

These clouds of gas move closer together and form a ball.

The ball gets hotter and starts to make energy.

As energy is made, the ball gets bigger and bigger until it forms an adult star.

Stars continue to burn for about 10,000 years until they consume or use all the hydrogen gas that is in them.

When all the hydrogen is gone, the star dies.

All stars turn into red giants or super giants at the end of their lives.

RED GIANT

During the red giant stage, a star swells up so big, it could swallow Earth, Venus, and Mercury.

As a star continues to grow it eventually starts to run out of energy.

It will collapse and shrink and become a nova that continues to emit some energy for awhile.

When all the energy is gone, it becomes a white dwarf or black dwarf star.

It is then a dead star and creates no energy and drifts in space.

SUPER GIANT

continues to build energy creates an massive explosion called a supernova spews energy into space becomes a nebula

Nebulas are clouds of gas and dust floating between the stars that are recycled to form new stars.

nebula gas

These clouds of gas and debris floating in space are called interstellar dust.

These clouds of dust get thicker as they combine together, form balls of energy, and over a span of thousands of years, form a new star.

nebula hydrogen gas

Wolf-ray nebula

ring nebula

nebula

Close up view stars

plasma

BLACK HOLE BLACK HOLES

formed from dying stars when certain stars die they create a gravity around them the gravity spins faster than the speed of light Make a vacuum similar to a “tornado” that sucks anything too close into its spinning core

black hole

Asteroids are basically small planets that move in orbit around the sun.

Within the Milky Way, there is a huge collection of asteroids called an asteroid belt.

This belt is found in the space between two of our planets, Mars and Jupiter. This belt contains thousands of these asteroids

The largest asteroid known is Ceres which is about 640 miles in diameter.

Meteors are small, solid bodies that enter a planet’s atmosphere.

If a meteor reaches earth intact, it is called a meteorite.

There have been several craters in the world created by meteorites.

Meteor Crater in Arizona

Comets are small bodies that are characterized by a long, glowing tail.

Comets revolve around the sun and consist of dust and ice.

The tail of a comet is only visible as it passes in front of the sun and the reflected light makes the ice particles shine.

The main parts of a comet are the tail, nucleus, and the coma.

Comets are classified into two types, based on the length of the time it takes them to orbit around the sun once.

short period comets (like Halley’s Comet) orbit the sun in under 200 years long period comets take over 200 years to orbit the sun, even sometimes taking thousands of years

comet

Satellites are objects that revolve around a planet or star Satellites are objects that revolve around a planet or star. Example: moon