protostar - it's  tiny!

Hello, reader! Today the topic is . . . the Life Cycle of a Star! 
Yes, stars have life cycles, just like anything else.  Stars begin in a stellar nursery.  A stellar nursery is a nebula (a cloud of gas and dust) that houses young stars.  The next phase is a protostar, which is another word for a young star.  After a while, there's so much pressure that hydrogen and helium atoms start smashing into each other.  This creates nuclear fusion, which powers the star.  Nuclear fusion does two things:  it makes ignition and it makes lots of light and heat (otherwise known as energy).
This is a picture of a protostar.

Next, the star enters its mid-life.  This is known as its main sequence, and it is the longest part of a star's life. Our sun is in its main sequence right now.  Our sun is less than halfway through its life cycle.  It will live about 10 billion years. 
At mid-life, a star can be any size.  A star's size depends on how much matter it sucks in. 

red giant - it's huge!

Finally, a star reaches the end of its life.  How a star dies depends on its mass.  If the star is small, it will slowly lose layers and only its core, called a white dwarf, will remain. The lost layers of the star will form a cloud around it.  This is called a planetary nebula.  If the star is big, then it will become a red giant, expanding its outer layers.  See that picture off to the side?  That's a picture of a red giant. 







A star's life is a constant battle between nuclear power and gravity.  But in the end, gravity always wins.  It shoves the layers deep into the core.  But the core has too much pressure and releases a shockwave of nuclear energy called gamma rays.  These powerful energy bursts are also known as super-, or hyper-novas, depending on the star's size. 

Hello, reader! Today the topic is....black holes! A black hole is a very dense region of space.  We're  not exactly sure how black holes are formed but scientists think there are at least two ways:

(1) A large star goes ka-boom (in other words, it dies).  How exactly does a star "die"?  Well, stars need fuel to exist.  They burn fuel constantly.  This burning counters the effect of gravity that's always present.  Eventually, the star runs out of fuel and there's nothing left to counter the force of gravity.  The gravity overwhelms the fuel that is pushing out and it compresses the star.  Sometimes the star simply collapses and sometimes the star implodes.  This forms a black hole.  A supernova is a normal size star the turned into a black hole.  A hypernova is a large star that turned into a black hole.  When a hypernova goes out, the first thing it does is release a gamma-ray burst that can obliterate anything it hits. 

(2) A bunch of matter in the center of the galaxy gets shoved together by gravity (gravity is a bully).  Eventually the matter gets so tight it collapses in on itself.  This forms a black hole.

Black holes are completely invisible.  Nothing can escape once its pulled in (oooh, scary).  They have an edge, though, called an event horizon. If you passed that edge, you'd be spaghettified, (turned into individual atoms, not turned into a tasty snack). 

To understand black holes, you need to know space-time. Our universe is measured in a fabric-like material called space-time.  Our standard measurements, length, width, and height are each a dimension.  But time is another, totally different dimension.  When you combine all four, you get space-time.  Let me show you. See, if you drop a ball onto stretchy fabric, you get a hole,....almost. That is gravity! And mass! But this tiny ball doesn't create a huge black hole. Now, let's imagine using an 8-pound dumbbell. It actually tears space-time like cheap rubber!  This creates a huge black hole in the fabric.  Get it?  Good.
 

The Milky Way galaxy is epic! Wait, what is the Milky Way galaxy?  It sounds delicious!
Hmm...it's a barred spiral galaxy...and it has a bunch of hard-to-pronounce arms...but definitely no milk (or chocolate or caramel.  Booo.)  It's not called the Milky Way because it has some delicious ingredients.  It's called that because it's looks hazy and milky from Earth.
Now for those ridiculously named arms:
The arms are named after the constellations that are seen in those directions.  Ummm, by the way, a constellation is a group of stars that form patterns.  Just so you know.
Let's see . . . the major arms are Cygnus, Perseus, Sagittarius, and Centaurus.
Our solar system is in a minor arm called the Orion spur.  I hate being in a minor arm.  Why not a major arm, huh?
Our arm is almost on the tip, so we can see outside of the Milky Way.
The Milky Way galaxy has a black hole in the center.  It contains gas, dust, and dark matter.
Here is a far out picture (get it?  "Far-out!" Far out, like way out there?  Never mind.)