Morning distance
The morning distance is the angular distance measured on the horizon between the rising point of the sun or another star and the east point of the horizon, the evening distance correspondingly between the setting point and the west point .
Morning distance and evening distance depend on the geographical latitude of the observer and the declination of the star.
Today the term is used almost exclusively for the sun. Morning distance and evening distance are identical for the sun. If the sunrise is south of the east point or the sunset is south of the west point (in the winter half-year ), one speaks of southern morning range / southern evening range , otherwise (in the summer half year ) of northern .
At the time of the equinoxes , the morning and evening distances of the sun are 0 °. By contrast, the rising point is in Central Europe in the summer by up to 45 ° left or north of Ostpunktes (45 ° northern width morning) and in winter by up to 45 right or south of the Ostpunktes (45 ° southern Morning width) °; at the sinking point in relation to the west point it is exactly the opposite.
In areas of the earth where it is polar night or day , morning and evening distances are undefined.
The morning / evening distance was used by the earlier seafarers to calculate the magnetic declination (needle deviation from geographic north) when the location was roughly known . It can easily be calculated for a location using spherical trigonometry , provided the pole height of the location and the solar declination (distance from the celestial equator ) are known. For the latter, a small seasonal table or a sine- like graph is sufficient .
Individual evidence
- ↑ Morgenweit - Physics School. Retrieved July 29, 2019 .