🔍 Key Concepts

• Celestial sphere and how we imagine the sky around us • Difference between the point directly overhead and the point directly underfoot • How terms like pole and node are used in astronomy and navigation

💭 Think About

• Picture yourself standing on deck at night: what do we call the single point in the sky exactly above your head? • Think about which option is usually associated with the opposite point, directly below your feet through the Earth. • Consider which terms (pole, node, nadir, zenith) you’ve heard in connection with Earth’s axis or orbital crossings rather than overhead position.

✅ Before You Answer

• Identify which term means the point in the sky directly overhead the observer. • Identify which term means the point directly opposite that, beneath your feet. • Eliminate any terms you know are related to Earth’s rotational axis or orbital intersections rather than the observer’s local vertical.