1. How old is the earth? __ 2. What is a shooting star? __ 3. Of what is the moon made? __ 4. When was the last time humans set foot on the moon? __ 5. a) Name the two planets that are closest to the Earth. __ b) Have humans visited these planets? __ 6. How close is the nearest star? __ 7. What is a galaxy? __ 8. How big is the universe? __ 9. a) Is there life in our solar system other than on Earth? __ b) in the universe? __ 10. What is the difference between astronomy and astrology? __

1. Approximately **4.54 billion years** old.<br /><br />2. A "shooting star" isn't a star at all. It's a **meteor**, which is a small piece of rock or dust that burns up as it enters the Earth's atmosphere.<br /><br />3. The moon is primarily made of **rock and metal**, similar to the Earth's composition. It has a core, mantle, and crust, much like our planet.<br /><br />4. December 1972. Specifically, **Apollo 17** was the last manned mission to land on the moon.<br /><br />5. a) **Venus** and **Mars** are the two planets closest to Earth.<br /> b) Humans have not visited Venus, but robotic probes have been sent. Humans have also not visited Mars, but robotic rovers and landers have explored its surface.<br /><br />6. The nearest star (other than the Sun) is **Proxima Centauri**, which is approximately **4.24 light-years** away.<br /><br />7. A galaxy is a vast collection of **stars, gas, dust, and dark matter** held together by gravity. Our solar system is located in the Milky Way galaxy.<br /><br />8. The size of the observable universe is estimated to be around **93 billion light-years** in diameter. It's important to note that this is just the observable part; the entire universe may be much larger, perhaps even infinite.<br /><br />9. a) Currently, there is **no confirmed evidence** of life elsewhere in our solar system. However, scientists are actively searching for signs of past or present life, particularly on Mars, Europa (a moon of Jupiter), and Enceladus (a moon of Saturn).<br /> b) Whether life exists elsewhere in the universe is **unknown**. Given the vastness of the universe and the sheer number of stars and planets, it's considered statistically probable, but we have no definitive proof.<br /><br />10. **Astronomy** is the scientific study of celestial objects (stars, planets, galaxies, etc.), space, and the physical universe as a whole. **Astrology**, on the other hand, is a belief system that suggests that the positions and movements of celestial objects can influence human affairs and terrestrial events. Astronomy is a science based on observation and evidence, while astrology is not considered a science.<br />