Virtual Starship
(Star View)
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Expertly designed by Edward R. Hobbs
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StarView enables you to take a fantasy flight among the stars in the Sun's immediate
neighborhood. It will tell you what the Sun looks like from Sirius and
Altair.
It will even provide you with stereoscopic views and astronomical data which you can
use to select a star that is likely to have Earthlike planets.
Acknowledgments
StarView is based on data from The Astrogator's Handbook by Michael McCollum.
This reference contains a wealth of information on locating stars that could support
habitable planetary systems, along with detailed data on the 272 stars closest to Earth.
Using the View Window
The view window occupies most of the area of the StarView applet. It represents the
view from the front of your virtual spaceship. As you move the mouse pointer near each
star, its name appears, and information about the star is listed just below the view window.
Clicking the mouse button will instantly transport you to the currently selected star, with
the front of your ship facing the Sun.
When the program starts, your ship is located at the Sun, and the nose is pointed
in the direction of Earth's north pole.
Interpreting Star Data
Information on the currently selected star appears just beneath the view window. One set
of data is shown for single-star systems; multiple sets are shown for systems which are
comprised of more than one star.
| Name |
The name of the star appears on the first line of the display.
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| Luminosity |
The second line of the display shows the star's
luminosity (the
amount of light which comes out of a star every
second.) Use this number to compare the star's energy output to that
of the Sun, whose luminosity is approximately 1. Extremely dim stars
are unlikely to heat any of their planets sufficiently to produce conditions
conducive to life. Very bright stars tend to burn out quickly, and life
would not have sufficient time to evolve on their planets.
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| Distance |
The third line of the display shows the star's distance (in light years) from the
user's current location.
A
light year is
the distance light travels in one year - it's about
6,000,000,000 miles. |
| Spectral type |
The fourth line of the display shows the star's
spectral type. (When
light goes through a prism, it splits into different
color patterns. Spectral type is the classification of
these color patterns.) Keep in mind that extremely energetic stars (those of types
O through A) will blast their planets with high doses of ultraviolet radiation,
which is detrimental to the evolution of life.
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Operating the Mode Switches
Four mode switches are located at the bottom of the StarView applet. Click on these
buttons to use the controls associated with the various operating modes.
| Navigate |
Use these controls to move your ship through space or to point it to a
particular spot in the sky.
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| Style |
These controls affect how the stars are drawn in the view window.
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| Jaunt |
Select this button to see a list of stars that you can instantly
jump to. If the stars are your destination, then jaunting
(taking a short
trip) is
the only way to go.
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| Look At |
Pressing this button will produce the same list of stars as the
Jaunt button. Select one of these stars, and it will be centered in
the view window. (You cannot view the star that you are currently
visiting, because the light would fry your monitor.)
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Coordinate Systems
Before using the navigation controls, it is first necessary to understand the StarView coordinate
systems. The light
year (the
distance light travels in one year - about 6,000,000,000,000 miles)
is the unit of distance used by the program. Each star is
assigned coordinates relative to the location of the Sun.
The Z axis of the celestial coordinate system coincides with the Earth's axis of rotation;
the positive end of the Z axis lies in the direction of the Earth's north pole. The X axis
points to a location in the sky which is known as the first point in Aries,
while the Y axis points toward a spot in the constellation Orion.
Your ship has its own coordinate system. The positive Z axis points from the nose
of the ship. The Y axis points from the ship's belly, and the X axis points from the right
control fin (which is so vital to maneuvering in the vacuum of space).
As seen in the applet, the ship's Z axis points directly into the center of the view window;
the X axis points toward the right edge of the view window, and the Y axis points toward the
bottom edge.
When the program starts, the origin and axes of the ship's coordinate system coincide
with those of the celestial coordinate system; that is, your ship is aligned with Earth's north
pole, and the first point in Aries is to your right.
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Navigation Control Panel
The three slider controls at the top of the panel (marked "Absolute motion") move the ship along
the axes of the celestial coordinate system. The three slider controls at the bottom of the
panel (marked "View motion") move the ship along the axes of the spaceship coordinate system; the
slider marked "Z" corresponds to the ship's thrust control.
Your ship's current coordinates are displayed just above the View Motion sliders. These are
expressed as the distance of the viewpoint from the Sun in light years, along the axes of the
celestial coordinate system.
The axes near the center of the panel control the orientation of your spacecraft. They
represent the axes of the spaceship coordinate system. Click-and-drag on this area to change
the direction that your ship is pointing. These axes exist in three dimensions, but due to the
limitations of computer displays, they must be drawn in two dimensions. The intensity of the
colors indicates the third dimension: brightly colored axes are "pointing out" of the plane
of the screen toward the viewer; dim axes are "pointing into" the plane of the screen away from
the viewer.
Beneath the orientation axes are two rows of numbers; these indicate the
Right Ascension (a
number which measures the East-West position of a star) and
Declination (angular
distance of a star north or south of the celestial equator)
of the spaceship's
Z axis. These values can be used for specifying a spot on the
celestial sphere (an
imaginary sphere on which the stars and planets are placed so
astronomers can chart their positions - it's like a giant globe
that surrounds the Earth),
much as longitude and latitude are used to fix one's position on the surface of the Earth.
Style Control Panel
The three buttons toward the top of the panel control the size of each star drawn in the view window.
| Magnitude |
The size of each star is determined by its apparent magnitude
(how bright a star looks
in the sky - this can fool us because a star that looks
dim can be really very bright - it just might be really
far away),
as viewed from the current location of the spaceship. The largest stars are of
magnitude one and brighter. The smallest stars are of magnitude six and dimmer.
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| Luminosity |
The size of each star is determined by its absolute magnitude
(the actual brightness
of a star - pretending that the star is 10 parsecs away
from us.)
This means that stars with greater intrinsic luminosity
appear larger, regardless of their distance from the viewer's spacecraft.
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| Distance |
The size of each star is determined by its distance from the viewer's spacecraft; closer
stars appear larger, while more distant stars appear smaller. Neither the brightness
nor the actual size of the star play any role in calculating its size as drawn by the program.
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The Zoom slider, located near the center of the Style Control Panel, controls the focal length
of the virtual camera used to view the stars. Moving the slider to the left decreases the
focal length, resulting in wide-angle views. Moving the slider to the right increases the
focal length, resulting in telephoto views. Note that extremely wide-angle views can cause
"fisheye" distortion in the image.
The Mono and Stereo buttons enable stereoscopic views. To enjoy the full stereoscopic effect,
the use of an adjustable stereo viewer (a
black box of dimensions 7-1/2 x 2-1/2 x 4 inches with one edge
curved to fit over your eyes (or glasses) - each eye has a set of
mirrors for directing the view of that eye - the outer mirrors
are adjustable with a knob at the top of the box - this knob
adjusts where the 'stereo window' appears - the knob can even be
adjusted to switch images on the eyes, or left sees right image
and right sees left image (crossed stereo)) is recommended. The Stereo Separation slider controls the length of the baseline between the
"left" and "right" cameras used to render the stereo images; this length can be adjusted from zero
to 1.3 light years.
Jaunt
Control Panel
This panel contains a list of stars that are possible Jaunt destinations. Use the slider
along the right edge of the list to scroll through the star names. Click on a name, and you
will be instantly transported to the selected star. Upon your arrival, the nose of your ship
will be pointing towards the Sun.
"Look At" Control Panel
This panel contains a list of stars in the StarView database. Use the slider
along the right edge of the list to scroll through the star names. When you click on a name,
the selected star will be centered in the viewscreen. Stars in the immediate vicinity (.01
light-year radius) of your current location will not be visible.
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