Chapter 2 Flashcards
Celestial Sphere
A useful, albeit imaginary star map, which plots the stars, planets, and other celestial objects on a sphere reaching out into space with Earth at its center.
What is the difference between the Celestial North Pole and the North Pole.
The celestial north pole reaches out from the earth’s surface and extends into space. The North pole is a point on the earth’s surface.
What is declination and how is it measured?
Declination is the distance north or south of the celestial equator as measured in degrees (0 degrees to 90 degrees)
What is right ascension and how is it measured
Equivalent to longitude. Measured in hours, minutes, seconds of the rotation of the earth.
What is the ecliptic?
The sun’s path through the sky throughout the year.
Zenith
The point in the sky directly above you. (Imagine meditating on the ground and a line sprouts from your head and extends into the sky)
Explain horizon and meridian
As mapped out on the celestial plane the horizon extends perpendicular to the ground in all directions and the meridian slices from north to south in all directions on the celestial sphere..
Nadir
The point directly below you.
How do the stars appear in the night directly at the north pole?
Stars rotate around polaris like a carousel.
Where is the point on earth where the Zenith remains the same throughout the day?
The North Pole, and South Pole (but the stars rotation clockwise)
How does the NCP appear as you move north and south?
The NCP is high in the sky in higher altitudes and lower in the sky at lower altitudes until you reach the equator and the NCP is on the horizon.
How long do stars appear in the sky? How does this depend upon your location
Depends on your location. Except for at the poles, objects on the celestial equator appear in the sky 12 hours each day. Objects north of the equator, appear for more than 12 hours each day and objects south appear for less than 12 hours each day.
How can you use the north star to calculate the size of the earth?
By measuring degree changes in sky from locations north or south from each other. For instance if you travel 290 km north and the north star changes from 33.5 to 36 degrees, this would result in 42,000 when multiplied.
Why do we not feel the earth rotating?
It is due to our frame of reference. because we’re traveling at a consistent speed and the direction of the earth changes very slowly, we do not feel the earth rotating.
What is relative motion?
The difference in motion between two different frames of motion.
Coriolis Effect
The curving motion which results from the difference in rotation speed at different altitudes.
What are the two major factors which create the change in seasons?
The tilt of the earth. The angle that the sun’s rays hit the Earth’s surface.
Summer Solstice
Sun rises farthest north east and sets farthest north west as it crosses the meridian. June 20th
Winter Solstice
December 21st. Furthers south of the equator.
On what two days does the sun cross the celestial equator?
The Autumn Equinox on September 22nd and the vernal equinox on March 20th.
When does the equator get the most direct sunlight.
The first day of spring and the first day of autumn when the sun passes directly over the equator.
When is the sun above the horizon for 24 hours in the arctic/antarctic circle?
During the Summer and Winter Solstice and the days surrounding the solstice
