Below are HR diagrams taken of 4 star clusters. Identify the ages of the star cluster from YOUNGEST to OLDEST and describe in detail how you can determine the relative age of each cluster. Use the HR diagram provided at the end of this exam as a guide in your decision making process.
 Assume that the four planets listed in the table below are all terrestrial-type worlds, they formed at the same time, they orbit the same star, and each has nearly circular orbits.
(a) Which of the four planets should show the most seasonal variations over its orbit? Explain your reasoning.
(b) Which of the four planets is the most likely still to be geologically active? Explain your reasoning.
 The Big Bang theory of Cosmology is accepted by nearly all astronomers. Please list, and describe, three major observations that support this theory.
 Use your textbook and the internet to research the issues involved with human space travel within, and ouside of, the solar system. List some of the issues that make human space travel within the Solar System difficult. What are the factors that make human interstellar space travel unlikely – even in the distant future?
If they exist, what implications does this have for contact between advanced civilizations in the Universe?
 Of the various astronomers we’ve discussed in the course, please choose one that you think is the most influential and write a short paragraph about him/her. Include specific contributions.
 Exoplanets or extrasolar planets are planets that orbit stars other than the Sun. Do a web search for Exoplanets. How many of these planets are thought to have been detected? How were they detected? Do any of these planets orbit stars similar to the Sun? Are any of these planets similar to the Earth in terms of size and mass?
 Give a brief description of the shape and structure of the Milky Way. How do we know it is the shape it is? Where are we located within it?
 .Please refer to the H-R Diagram posted elsewhere in this conference for this question.
a. Where on the diagram would one find stars most like our Sun?
b. Where would one find objects of the smallest size (radius)?
c. Where would one find stars has of the largest size (radius)?
d. Where would one find stars that will burn out the fastest?
9)Two stars have the same radius but have very different temperatures. The red star has a surface temperature of 3000 K and the blue star has a surface temperature of 15,000 K. Using one of the formulas from the formula sheet , by what factor is the blue star more (or less) luminous compared to the red star? (for example, 2 times, 10 times, 100 times?)
 Below are HR diagrams taken of 4 star clusters. Identify the ages of the star cluster from YOUNGEST to OLDEST and describe in detail how you can determine the relative age of each cluster. Use the HR diagram provided at the end of this exam as a guide in your decision making process.