The celestial sphere, the coordinates system, seasons ...
[Pages:73]The celestial sphere, the coordinates system, seasons, phases of the moon and eclipses
Chapters 2 and S1
The celestial sphere and the coordinates system
Chapter S1
How to find our way in the sky? Let's start with the Earth Coordinate System
Latitude: N-S of the equator, Longitude: E-W along equator
From Earth to Space
The Celestial Sphere
? The Celestial Sphere: An
imaginary sphere of infinite
radius centered on Earth. ? The extensions of the Earth
North Celestial Pole
North and South Pole define
the North and South celestial
poles.
? The projection of Earth equator defines the Celestial equator.
? Celestial Sphere can then be divided into a grid, just like the Earth is divided into a grid of latitude and longitude.
North celestial poleNorth
Celestial Equato r
South Celestial Pole
The Celestial Sphere: Motions
? Stars, planets and Sun are "attached" to this imaginary sphere.
? As the Earth rotates, the celestial sphere (with the stars attached to it) appears to rotate in the opposite direction.
? To explain the daily motions of the sky you can imagine the sphere rotating once in 23 hours 56 minutes (using a star as reference).
Celestial Sphere: Measuring Angles
Longitude (E ? W along Equator) Latitude (N ? S of Equator)
The celestial coordinate system
RA, measured in hr, min, sec
(0 to 24 hours)
1 hour = 60 min 1 min = 60 sec (1 hour = 15 degrees of Earth rotation)
Dec, measured in degrees, arcmin, arcsec
(0 celestial equator, +90 north hemisphere, -90 south hemisphere)
1 degree = 60 arcminutes 1 arcminute = 60 arcseconds
Celestial Equator
Right Ascension (RA)
Declination (Dec)
North Celestial Pole
orth celestial poleNorth
South Celestial Pole
The use of RA and Dec to locate objects in the celestial sphere
There are two coordinates that allow to locate an object in the sky: Azimuth and Altitude. Their value depends in the location of the observer Azimuth: Use as reference the north direction (close to Polaris) and the range of values is from 0 to 360 degrees. 0 degrees is N, 90 degrees E, 180 is S and 270 is W. Altitude: Use as reference the horizon. The range of values is from 0 degrees (horizon) to 90 degrees (zenith)
Locating the star Vega and the Sun in the celestial sphere
Ecliptic: Apparent annual path of the Sun in the celestial sphere The Sun crosses the celestial equator on March 21 (Spring equinox) and on September 21 (Fall equinox) The Sun reaches a declination of +23.5 degrees on June 21 (Summer solstice) The Sun reaches a declination of ? 23.5 degrees on December 21 (Winter solstice)
................
................
In order to avoid copyright disputes, this page is only a partial summary.
To fulfill the demand for quickly locating and searching documents.
It is intelligent file search solution for home and business.
Related download
- technical definition of the ecliptic calendar
- solstice and equinox curriculum digitalis
- solstice and equinox curriculum cosmic adventures
- earth s seasons equinoxes and solstices 2018 2025
- solstice and equinox curriculum
- the celestial sphere the coordinates system seasons
- obliquity and precession of the equinoxes
- define rotation revolution solstice and equinox
- workbook the equinox and solstice cycle
Related searches
- why the school system is bad
- is the education system broken
- the school system is broken
- the education system is failing
- why the education system is good
- changing the school system essay
- the college system is broken
- the education system is broken
- the school system is bad
- the planets of the solar system song
- the organs in the circulatory system include
- nad 83 coordinates system x and y