TITLE: The Evolution of the Solar System

Lecture Script:

Professor: Good afternoon, everyone. Today, we're going to delve into the fascinating evolution of our solar system. Our solar system formed about 4.6 billion years ago from the gravitational collapse of a region within a large molecular cloud. This collapse triggered the formation of the Sun and the surrounding planetary bodies. A key aspect of this process was the conservation of angular momentum. As the gas cloud contracted, it spun more rapidly, eventually flattening into a disk with the Sun forming at its center.

Now, let's consider the role of accretion in forming planets. Accretion is a process where solid particles collide and stick together, forming larger bodies. Initially, these were small particles of dust and ice. Over time, they collided and merged to form larger planetesimals, which eventually combined to form protoplanets. In the inner regions of the solar system, where it was warmer, rocky planets like Earth and Mars formed. In contrast, the cooler outer regions allowed gas giants like Jupiter and Saturn to develop, capturing large amounts of hydrogen and helium.

Student: Professor, how do we know this process occurred?

Professor: That's a great question. We have several lines of evidence. For instance, meteorites, which are remnants of early solar system material, show a composition that matches our theoretical models of solar system formation. Additionally, telescopic observations of other star systems at various stages of development provide a snapshot of what our solar system might have looked like at different points in its history.

Moving on, let's discuss the late heavy bombardment period. This was a time, roughly 4 billion years ago, when the planets experienced intense comet and asteroid impacts. The cause of this bombardment is still debated, but one leading theory suggests that it was due to the gravitational effects of the gas giants, which sent a cascade of debris into the inner solar system.

In conclusion, the study of our solar system's evolution is a dynamic and ongoing field. With advancements in technology, we are continually uncovering new insights that challenge and refine our understanding.

Questions:

1. What is the main topic of the lecture?
   A) The formation of stars B) The history of meteorites C) The evolution of the solar system D) The discovery of exoplanets
   
2. According to the professor, how did the solar system begin to form? A) Through the explosion of a supernova B) From the gravitational collapse of a molecular cloud C) By the collision of two galaxies D) From the fission of an older star
   
3. What role does accretion play in planet formation?
   A) It causes stars to form B) It leads to the creation of gas clouds C) It helps in the formation of larger planetary bodies D) It prevents planets from developing
   
4. Why does the professor mention meteorites in the lecture?
   A) To explain their impact on Earth B) To show evidence of solar system formation C) To describe their chemical composition D) To compare them with asteroids
   
5. What can be inferred about the late heavy bombardment period?
   A) It was caused by the Sun's expansion B) It exclusively affected the outer planets C) It may have been influenced by the gas giants D) It was a short, insignificant event
   
6. How does the professor transition from the discussion of planet formation to the late heavy bombardment?
   A) By discussing the role of the Sun B) By explaining the effects of gravity C) By highlighting technological advancements D) By mentioning the impact on Earth's atmosphere
   

Answer Key:

1. (C)
2. (B)
3. (C)
4. (B)
5. (C)
6. (B)