User`s guide

Bending Space & Time 109
plane is given by X and Y coordinates.
The Z coordinate takes the location out of
the plane of the ecliptic. For spherical
co-ordinates, “radius” is the distance from
the Sun’s centre, “theta” is the position
angle from the ecliptic plane, and “phi” is
the position angle along the ecliptic plane.
Heliocentric means that the Sun is the
centre of the coordinate system, so the
point (0,0,0) is at the centre of the Sun,
using either Cartesian or spherical
co-ordinates.
Note: When you switch from a location on
Earth to a stationary location, the initial
co-ordinates listed are the current
heliocentric co-ordinates of your current
Earth location. If you select these
co-ordinates and advance time forward,
you’ll quickly be left behind as Earth
continues on in its orbit, while you remain
at the same position in space.
Planet Fly-bys: There are times when you
may want to watch a celestial event from a
fixed point in space. Using the elevation
controls, rise above a planet and then
switch to a fixed heliocentric location.
Increase the rate at which time flows and
you can watch a planet fly past in its orbit.
If you have elevated from the planet’s
surface in the direction that it is traveling,
you pass directly through the planet as it
moves forward in its orbit!
Tip: Noon or midnight is a good time to try
fly-bys, since you are lifting off in a
direction that is perpendicular to the
direction of the planet’s orbit.
Orientation
Now that you know
how to change your
viewing location, there
may be times when you
also wish to change
your orientation. Orientation refers to the
way you align yourself - which direction is
“up” and which direction is “down”. When
referring to a computer program, the
question becomes which direction in space
points to the top of the screen, and which
direction points to the bottom.
You can change your orientation in Starry
Night by choosing Options->Orientation
from the menu. The most familiar and
intuitive orientation is the local
orientation, which Starry Night uses by
default. Local orientation orients you
relative to the horizon, with the point
directly above you in the sky at the top of
the screen, and the point directly beneath
your feet at the bottom.
Now, imagine you are on the space shuttle.
Because you are floating freely in space,
your orientation is no longer obvious —
the points directly above and below you
are not fixed. You could mimic the local
orientation by pointing your feet at your
backyard on Earth, but you could just as
easily align yourself with the axis of
Earth’s rotation. Starry Night refers to that
alignment as the equatorial orientation.
In local orientation, Starry Night keeps
your feet pointed directly toward the
center of the Earth. In the equatorial
orientation, Starry Night keeps the North