This is an example of a Spiral Galaxy looking at it from the side.  In the center you'll see the central bulge this is the center and looks like a really bright baseball. It's made up of old stars, gas, and dust. The disk is the part that looks like the side of a sombrero hat. These are what the arms look like from the side when they are flattened. The arms normally from another view stretch out like the sides of a pinwheel (spiral arms) and are made of dust, gas, and young stars as they wind away from the central bulge.  The halo is the eerie light that shines outward around a galaxy.

Spiral Galaxies come in two types: Barred and Spiral. A Barred Spiral Galaxy will have a "bar" in the middle where the center is. A boxy light that appears longer than a simple bright dot in the middle. Then the pinwheel arms or  spiral arms.  The "bar" in the middle is made up of stars and interstellar matter. A Spiral Galaxy will have no boxy light in the middle. It will just look like a bright dot that the pinwheel arms or spiral arms move out of.   They will have a "bulge" in the center like a big bright baseball and a disk around them.  The bulge will give off a bright eery light called a halo.  They have lots of gas and dust. Young and old stars.

While Spiral and Barred Spiral Galaxies  have pinwheels or spiral arms..... Elliptical Galaxies look like..... FOOTBALLS!!!! Sometimes they just like poorly made footballs and are more round than elliptical.  They have a bulge  but no disk.  Notice the eerie glowing halo though.  It's mainly made up of old stars and a little cool dust and gas.

Is that a nebula?????? Nope. But it looks like a nebula!!! Nope. Why isn't it a nebula??? Because it is HUGE!!!!! Irregular Galaxies  may look like nebulae but they aren't. Galaxies are huge and are filled with 100's of billions of stars. Millions of Nebulae. They have tons of gas and dust. New and old stars.  But why then is it shaped so weird? Well, cause alot of galaxies just don't come in a regular shape like Elliptical and Spiral Galaxies do. So, we call them Irregular.

Don't forget about our Celestial Hokey Pokey! The earth is tilted on it's axis (the red line) at an angle of 23.5 degrees. That means what we think of as straight up and done is not straight up and down for the rest of the solar system. We "walk" crooked like the leaning Tower of Pisa.  While everything else including the people is straight up... the tower leans. The same is true of our solar system. While most things stand up straight as they rotate around the sun.... we rotate around without standing up straight. Like the tower we lean at an angle. 23.5 degrees  While  Zenith  is like a "true north" for the Sun, it's not the same as our north because... we lean. Our north instead is called the Celestial North Pole.  The same is for Nadir and Celestial South Pole. Nadir is the "true south" of the Sun. But because we lean our south isn't exactly lined up. So, ours is called the Celestial South Pole.  Now the Ecliptic and Horizon go together. The ecliptic is the line that cuts right across the stomach of the Sun. That line stretches out across the solar system. When it cuts across the stomach of the Earth we call it the horizon.  But this is the angle from the Sun. Again, because we are tilted we like to think that when you cut a line across the Earth's stomach you get the Celestial Equator. The Ecliptic and Celestial Equator  do not overlap because we are.... tilted! Now, if you were to cut a line down the Earth from head to toe, right down its axis, this line would be called the Celestial Meridian.

Remember, there is a difference between rotate or rotation and the word revolve or revolution.  When you rotate you are spinning on your own in a circle like a ballerina.  When you revolve  it's like you have a partner that your job is to spin around them! When the earth spins or rotates  one full spin on it's axis this length of time is called a day or 24 hours. When the moon takes a trip around the earth by revolving around us, a full journey all the way around is a month or 28 days. When we, the earth, revolve around the Sun, to go around one whole time takes a year or 365.25 days (This is why every 4 years February gets an extra day, the .25 after the 365.