In astronomy, the meridian is the great circle passing through the celestial poles, as well as the zenith and nadir of an observer's location. Consequently, it contains also the north and south points on the horizon, and it is perpendicular to the celestial equator and horizon.

In astronomy, coordinate systems are used for specifying positions of celestial objects (satellites, planets, stars, galaxies, etc.) relative to a given reference frame, based on physical reference points available to a situated observer (e.g. the true horizon and north to …

Since we live on Earth, we see only half of the celestial sphere. It is called the local sky. Two angle measurements are required to locate any object in the local sky. Each angle has a zero point. Altitude (elevation) - Starts from the horizon rises …

RA, Dec: an object’s fixed coordinates on the celestial sphere, do not change as celestial sphere rotates. Alt, Az (and HA): an object’s local sky coordinates, change throughout the night. Declination (δ) is always measured in degrees (°), minutes (ʹ), and seconds (ʺ) …

Figure 2.3 shows how we represent the local sky. Notice that we define three key “landmarks” in the local sky: The horizon defines what appears to our eyes to be the boundary between Earth and sky. We can mark the horizon with compass directions.

Study with Quizlet and memorize flashcards containing terms like WHY DOES THE LOCAL SKY LOOK LIKE A DOME? DEFINE HORIZON, ZENITH, AND MERIDIAN. HOW DO WE DESCRIBE THE LOCATION OF AN OBJECT IN THE LOCAL SKY?, EXPLAIN WHY WE CAN MEASURE ONLY ANGULAR SIZES AND ANGULAR DISTANCES FOR OBJECTS IN THE SKY.

• How do stars move through the local sky? Their paths depend on your latitude and the star’s declination. • How does the Sun move through the local sky? Sun moves like the stars except its declination depends on your latitude and the time of year.

Why does the local sky look like a dome? Define horizon, zenith, and meridian. How do we describe the location of an object in the local sky? The horizon is the boundary between the Earth and sky.

How do we describe the location of an object in the local sky? What are right ascension and declination? The horizon is the boundary between the Earth and sky. The zenith is the point directly overhead. The meridian is an imaginary half circle stretching from the horizon due south to the horizon due north, passing through the zenith.

Sky Map Online web app provides free & real-time interactive star map / sky charts for any location, time and viewpoint. It shows the night sky stars up to magnitude 12, planets, moon and DSO. It has zoom & pan, mobile & touch support, 3D …