User`s guide

112 Starry Night User’s Guide
ward. You can see the planets moving
around the Sun.
9 The innermost planets will be too close
to the Sun to really see. Use the Decrease
Elevation button to reduce your elevation
to about 10 AU (so that the orbit of Saturn
approximately fills the screen). You can see
that the inner planets move much more
rapidly. Change the time step to a discrete
value of 3 days to slow down the motion of
the planets.
10 Press the Stop button in the time
controls to stop the motion of the planets.
Click and drag the mouse (while holding
down the Shift-key) to shift your view of
the solar system. You should be able to
adjust your view so that all of the planet
orbits (with the exception of Pluto) fall into
a straight line. You are now viewing along
the plane of the ecliptic.
Spaceship Mode
Plug-in your joystick—
or use your keyboard
controls—to fly an intergalactic spaceship
anywhere within a virtual cube of real
space objects, 700 million light-years on a
side!
Spaceship mode lets you change your
location in a completely different way than
using the Go There option. It lets you
interactively drive through the universe.
Pressing the Spaceship button lifts you
above the Earth’s surface and calls a
heads-up display similar to the ones
fighter pilots use. The area inside the blue
rectangle is called the viewport, and the
motion of the spaceship is always towards
the area of sky at the center of the view-
port. To turn off spaceship mode, press
Spaceship again.
Speed: Two gauges beneath the main dis-
play measure the motion of your space-
ship. The top gauge measures your
velocity or speed. In order of increasing
speed, the markers are green, yellow,
orange and red. If you are in the green
range, you are traveling beneath the speed
of light, while yellow, orange and red are
all-greater than the speed of light. Your
speed is also shown in a numerical format
beneath the two gauges. It is given in km/s
for sublight speeds or units of 'c', which is
the speed of light. Values greater than 1c
are greater than the speed of light. The
lower gauge indicates how fast you are
accelerating or decelerating (i.e. changing
your speed). If your speed is increasing,
this gauge will be green, while if your
speed is decreasing, the gauge will be red.
Closest Object: The position of the closest
object inside the viewport is marked by
cross-hairs on the display screen. The
name and distance to the object are shown
just to the right of the display. You may
also see a second object marked by cross-
hairs, which is outside the viewport. If so,
then this object is even closer than the
object marked inside the viewport. If no
second object is marked by cross-hairs,