Mrs. Degl1 Beyond our Solar System Solar System - consists of 1 or 2 stars, planets, satellites, asteroids, meteors, and comets Galaxy – consists of about 1 billion stars and possibly their solar systems Local Group – our Local Group contains our Milky Way and about 28 other galaxies Cluster – a group of 100 galaxies Supercluster – a group of clusters Universe – there is an estimated 50 billion galaxies in the Universe. No one really knows where the Universe ends or if it does end. We do not even know what shape it has. Does it extend outward in every direction?

Mrs. Degl2 The Nebular Hypothesis – the theory on how our Solar System formed. Our Sun formed in this nebula. It was quite an explosion (nuclear fusion) that sent a lot of extra material propelling into space. All of this left over material that did not get used up in the formation of the Sun was still spinning around in space. Eventually it all combined together because of gravity. The inner planets formed next, and kept spinning. The inner planets are made of the heavier elements. The left over light material kept propelling into space and eventually these light materials came together because of gravity and formed the outer gas planets. That is why the inner planets are made of more dense materials than the outer planets. Only light gasses could make it so far out into space. Sun Inner Planets Outer Planets That’s the order!!

Mrs. Degl3 There are 4 types of Galaxies 1.Spiral 2.Barred 3.Elliptical 4.Irregular (These are the most common) (Our Milky Way Galaxy is a rotating Spiral Galaxy) (No shape) These are usually very young galaxies with very young stars.

Mrs. Degl4 The Earth is part of the Milky Way Galaxy. The next nearest is the Andromeda Galaxy. Our solar system is here Above is a side view of the Milky Way Galaxy. It is a rotating spiral galaxy. We live in one arm of the galaxy. The ball in the middle is called the Central Bulge. That is where most of the other star systems are located. That is what makes it much brighter.

Mrs. Degl5 Above is a top view of the Milky Way Galaxy. Since the galaxy rotates, the Sun "orbits" the center, taking 200 million years to complete one circuit.

Mrs. Degl6 This is the Orion Nebula, where other solar systems appear to be forming. Orion is located in the same arm of our galaxy (Milky Way). It takes light 1500 years to reach Earth from the Orion Nebula. Maybe the solar systems are already formed?

Mrs. Degl7 This is the Trapezium nebula. Here, you see solar systems forming.

Mrs. Degl8 The Big Bang Theory – theory on how the entire Universe formed. Estimated between 10 and 20 billion years ago. The Universe was once confined to a point of matter that was very massive, very dense, and very hot. This is before space and time existed. It is believed that there was an explosion so big that all of the matter in the Universe today was created in that explosion. Just like after any explosion, matter was thrown out in all directions. The same matter is still traveling outward today. It is believed that the matter closer to the center of the explosion came together to form stars and planets first. It seems like the distant parts of space are still forming. We can now prove that the Universe is expanding at an accelerating rate. That means that the speed of expansion is increasing all of the time. Stars and other objects that are further away from us are traveling faster than we are. We have evidence that the Universe is expanding. It is the Red Shift part of the Doppler Effect. Everything in space is moving away and we can tell by the increasing wavelengths of light that they give off.

9 This is the deepest view of space ever seen. It was taken by the Hubble Telescope and it tells us a lot about what is out there in the Universe. And this picture is only facing one small section of space. There are so many stars and galaxies. Who knows where the end is. And if the Universe is constantly expanding, is there an end?

10 What happened after Earth formed? It took quite a while for the planet to cool down. The inner Earth is still molten today. After most of the planet’s surface was solid rock, the inner Earth was still outgassing (giving off water vapor, carbon dioxide, methane, nitrogen etc..) There was virtually no oxygen. Steam from the cooling planet eventually condensed to form the primitive oceans. Bacteria were the first life forms on Earth, and it started in the oceans. Plants began to evolve because they breath carbon dioxide, not oxygen. These plants then began to release oxygen into the atmosphere and water. This caused the oxygen content to increase over time. It took about 4 billion years after Earth formed before there were any organisms that breathed oxygen. The Earth is 4.6 billion years old. The atmosphere was mostly Methane.