Lecture 2: The Sky and Daily Motion

A comprehensive set of flashcards covering key concepts from Lecture 2: The Sky and Daily Motion, including sky coordinates, Polaris, daily and annual motion, and time zones.

What are the three basic ways of locating objects in the sky?

Geography (constellations), Celestial Coordinates (Right Ascension and Declination), and Local Coordinates (Altitude and Azimuth).

What does Right Ascension measure?

The angular coordinate along the celestial equator (like longitude on Earth), usually expressed in hours.

What does Declination measure?

The angular distance north or south of the celestial equator (in degrees).

What do Altitude and Azimuth measure?

Altitude is the angle above the horizon; Azimuth is the compass direction from North.

What is Polaris?

The North Star, located near the North Celestial Pole, used to locate due North.

What is the azimuth of Polaris when it is due North?

0 degrees.

From Murfreesboro, TN, what is the approximate altitude of Polaris?

About 36 degrees.

How does observer latitude affect the altitude of Polaris?

Polaris' altitude roughly equals the observer's latitude; as you move north, Polaris appears higher in the sky.

What is daily motion in astronomy?

The apparent motion of the Sun and stars caused by Earth's rotation; objects rise in the East and set in the West.

In the Northern Hemisphere, around which point does the sky rotate daily?

Around the North Celestial Pole (near Polaris); the rotation appears counterclockwise when viewed from above.

What is the annual motion?

The apparent movement of the Sun and stars over the year due to Earth’s orbit around the Sun.

What is the connection between time and longitude?

Local solar time is tied to longitude; traveling East/West changes the Sun's position and the local time (time zones).

Name a program used to simulate star positions for demonstrations.

Stellarium.

What is Ursa Major commonly known as?

The Big Dipper, the prominent asterism in Ursa Major.

What is Alcor and Mizar?

An optical double star in the handle of the Big Dipper.

What are circumpolar constellations?

Constellations that never set below the horizon for a given latitude.

Name a circumpolar constellation near the North Celestial Pole.

Ursa Minor (the Little Dipper) is circumpolar near the North Celestial Pole.

What is the North Celestial Pole?

The point in the sky around which stars appear to rotate; located near Polaris.

What is the Big Dipper's significance?

It is an asterism in Ursa Major used for orientation and locating other stars.

Which direction does the Sun rise from and set to?

Rises in the East and sets in the West.

Which software is used to practice sky positions by time and location in the notes?

Stellarium (or similar sky simulation software).

Name the four primary U.S. time zones listed from west to east.

Pacific, Mountain, Central, Eastern.

Which U.S. state is noted as not observing daylight saving time except for the Navajo Nation?

Arizona.

Why is sunrise earlier in Murfreesboro than in Amarillo on the same date?

Because Murfreesboro is east of Amarillo in longitude, so local solar time is ahead.

What is the effect of the Earth's annual motion on sunrise times?

The Sun’s path changes with the seasons due to Earth’s orbit, altering sunrise and sunset positions and daylight length.