User`s guide

58 Starry Night User’s Guide
be at its highest point in the sky when it is
on the local meridian line.
Show compass indicator while scrolling:
This turns on or off the compass image in
the upper right corner of the screen, which
appears when you scroll around the sky to
help you determine your viewing
direction.
The Ecliptic: The ecliptic line is the
apparent path in the sky which the Sun
moves through over the course of a year.
Notice the constellations which the
ecliptic line passes through - these are the
familiar zodiac constellations. The Sun
will always be found directly on the
ecliptic line, while the Moon and planets
will always be found close by.
Zenith/Nadir: The zenith is the point in the
sky directly above your head, while the
nadir is the point directly below your feet.
Summer/Winter Solstice: The Summer
Solstice
is the Sun’s position relative to the
stars on the first day of summer (in the
Northern Hemisphere), while the
Winter
Solstice
is the Sun’s position relative to the
stars on the first day of winter. More
precisely, they are the Sun’s positions in
the sky at the two exact times when the
plane of Earth’s equator is inclined at the
largest angle (about 23.5 degrees) to the
plane determined by Earth’s revolution
around the Sun.
Vernal/Autumnal Equinox: The Vernal
Equinox
is the Sun’s position relative to
the stars on the first day of spring (in the
Northern Hemisphere), while the
Autumnal Equinox is the Sun’s position
relative to the stars on the first day of fall.
More precisely, they are the Sun’s
positions in the sky at the two exact times
when the plane of Earth’s equator is the
same as the plane defined by Earth’s
revolution around the Sun.
Guides Layer in Pro and Pro Plus
Axes: In Starry Night Pro and Pro Plus,
this option displays a 3-dimensional set of
reference axes and/or a reference plane for
the co-ordinate system in question.
Options for changing the look of the
reference axes are in the Guides Options
dialog box. It is not possible to turn on
reference axes for the alt/az system.
Equator: Displays the line of 0° “latitude”
for the co-ordinate system in question. For
the alt/az system, this is the horizon line.
For the equatorial system, this is the
celestial equator, a projection of Earth’s
equator into space. For the ecliptic system,
this is the ecliptic line, a projection of the