Hottest 6/Hottest 6 (1996)(PDSoft)[!].iso/pdsoft/demo_library/4460.lha/README

Text File | 1995-06-03 | 17KB | 391 lines

The animation included with this archive shows how the orientation
of Saturn's rings will change over the period from January 1995 to
May 1996.  For those who may not know what this is all about, or
why it is significant, the following press release from JPL may help:



------------------------PRESS RELEASE--------------------------
Douglas Isbell
Headquarters, Washington, DC               May 18, 1995
(Phone: [phone])

Mary Beth Murrill
Jet Propulsion Laboratory, Pasadena, CA
(Phone: [phone])

RELEASE:  95-72


SATURN'S RINGS: NOW YOU SEE THEM, NOW YOU DON'T

        The rings of Saturn will all but disappear for a few
moments on May 22 during a rare astronomical event that will
allow astronomers to look for new moons and other features that
are normally obscured by the glare of the dazzling rings.

        Many of the world's major telescopes, including NASA's
Hubble Space Telescope, will focus on Saturn during the 24-
minute event.

        The phenomenon is known to astronomers as a Saturn ring
plane crossing. This year and next, the rings will be seen
edge-on from the Earth's perspective on three occasions -- May
22 and August 10, 1995, and Feb. 11, 1996.  This event only
happens about every 15 years.

        Ring plane crossings provide astronomers with unique
views of the Saturnian system.  With the rings temporarily
invisible as viewed from Earth, faint objects near the planet
are easier to see.  Thirteen of Saturn's 18 known moons have
been discovered during past ring plane crossings.

        The faint, outermost E-ring also is easier to detect
when viewed edge-on due to the greater amount of material in
the line-of-sight.  Thus, observations made over the course of
the ring plane crossing also can be used to gather new
information on the thickness of the rings and to search for new
rings.

        The event is of special interest to scientists and
engineers at NASA's Jet Propulsion Laboratory (JPL), Pasadena,
CA, who are fine-tuning the flight path of the Cassini
spacecraft.  Cassini is scheduled for launch on a mission to
Saturn in 1997, jointly conducted by NASA, the European Space
Agency and the Italian Space Agency.  Any new data on the location
and density of material in the rings will help the Cassini team
plan the most advantageous and safest course for the spacecraft
to take when it flies through the rings upon arrival at Saturn
in 2004.

        "We're going in awfully close with Cassini," said
mission scientist Dr. Linda Horn of JPL, "so the more we know
about the boundaries of the rings, the more confident we'll
be."   Plans call for the spacecraft to fly through a 15,500-
mile (25,000-kilometer) gap between the F- and G-rings, then
closely over the broad C-ring.  Later, the spacecraft will make
several passes through the E-ring.

        Astronomers hope to refine measurements of Saturn's
small, inner moons during the ring plane crossing.  Better
estimates of the moons' sizes will be useful in targeting
Cassini's observations of those satellites, according to Horn.

        Saturn's rings are known to be numerous, dynamically
complex and made up of countless particles of ice ranging in
size from boulders to snowflakes, with some rock mixed in.
They are thought to be the remains of comets, meteoroids and
possibly small moons that have been captured and torn apart by
Saturn's gravity.

        The rings are a prime target for the science
instruments aboard the Cassini spacecraft, whose mission is to
study the Saturnian system while orbiting the planet for four
years.  Cassini also will carry the European Space Agency's
Huygens Probe to be dropped into the atmosphere of Saturn's
large moon Titan.  As it parachutes downward, the Huygens Probe
will return information about Titan's atmosphere and surface.
In some ways scientists believe Titan resembles Earth as it
existed in a primordial stage before life developed.

        The Cassini Project is managed by JPL for NASA's Office
of Space Science in Washington, DC.

                       - end -

----------------------END PRESS RELEASE------------------------


Due to the differing inclinations of the Earth's and Saturn's orbits,
we are fortunate in that we will actually be able to observe three
ring crossings.  Such a triple crossing will not occur again until
the year 2038.

According to the Catalina Observatory in Arizona, the following
timetable describes the significant events:

  May 22, 1995 0518 UTC - 1st Earth Crossing (24 minutes)
  Aug 10, 1995 2054 UTC - 2nd Earth Crossing (28 minutes)
  Nov 19, 1995 1509 UTC - Sun Crossing, No Shadow (3.8 days)
  Feb 11, 1996 2334 UTC - 3rd Earth Crossing (12 minutes)

For the period between May 22nd and August 10th, and again from
November 19th to February 11th, we will be viewing the side of
Saturn's rings which are not illuminated by the Sun.  As a result,
they appear dark.


The first crossing has already occurred.  The following Sky & Telescope
News Bulletin helps to describe some of the discoveries made during the
event:


------------------------NEWS BULLETIN--------------------------
Sky & Telescope's News Bulletin -
May 26, 1995



SATURN'S THIN RINGS

Earth's first of three passages through the plane of Saturn's rings occurred as
predicted on May 21st, and astronomers around the globe were watching.
Giant reflectors like the 10-meter Keck telescope, took images as the rings
tilted edge-on. According to Imke de Pater of the University of California at
Berkeley, images with the Keck telescope taken just before and after the ring-
plane crossing reveal several small moonlets within the rings. If you observe
Saturn right now you're not likely to see much except the planet's distinctly
flattened ball. Saturn rises only a few hours before dawn, so it's not
particularly well placed for viewing. If you have a good-size telescope you
might try to watch the planet's larger satellites play tag. Tethys, Dione, Rhea,
and Titan are undergoing eclipses and occultations by Saturn and one another.
A complete observing guide for Saturn's ring crossings begins on page 68 of
SKY & TELESCOPE's May issue.
----------------------END NEWS BULLETIN------------------------


Now, a few notes about the animation itself.  The orientation of the
image matches that of an inverting telescope - south is up and east is
to the right.  There are two times displayed at the top of the animation:
LT is the local time (set to Mountain Daylight Time by myself when I
created the animation), and DT is the Dynamical Time (almost the same
as Coordinated Universal Time, but since it is kept by atomic clocks, it
isn't a victim to irregularities in the Earth's rotation as is UT).

The dots that flick by in the image from time to time are some of
Saturn's moons.  Since the animation consists of only 100 frames over
the period of about a year and a half, the time between each frame is
far too great to make sense of the motion of the moons.

The animation starts as we view Saturn from slightly below the rings
(actually, this is viewing Saturn from its northern hemisphere - remember
the inverting telescope? :-)  The rings' orientation slowly changes until
they are edge-on on May 22nd.  Then, for a brief period until August 10th,
we are viewing Saturn from slightly above the rings.  However, since the
Sun is still shining from below the rings, we are viewing the dark side
of the rings (and hence, they appear a darker color in the animation).
We then view Saturn's rings from below once more.  On November 19th, the
Sun moves to illuminate the upper side of the rings, so they once again
appear dark.  The orientation continues to change until we view Saturn
from above, the sunlit side.  From then on (until the next ring crossing
15 years later), the rings open and remain sunlit.

While this is all going on, the Earth completes more than one full orbit
around the Sun.  As a result, the distance to Saturn changes rather
markedly, and the disk can be seen to be getting bigger and smaller
throughout the animation.

The animation was written from a commercial software package which is
currently in the final stages of beta testing (as is evidenced by its
version number of 0.96 appearing in the title bar of the animation).
It is hoped that this package, known as "The Digital Universe" will be
ready for shipping in a few months.  If you have any questions about
the animation or the software used to generate it, please send email
to [e-mail].

The animation should be playable with any IFF ANIM5 player.  I use
Viewtek, by Thomas Krehbiel.  If you use another animation player which
for some reason does not work with this animation (but has worked with
others), please let me know.  As the software is still in beta testing,
it is possible that a bug may exist in the ANIM generator.  If it does,
I would like to know about it (and repair it) before the software is
released.

I include a pre-release notice for "The Digital Universe" in this message.
Again, if you have any questions about the package (particularly if you
think you may be interested in purchasing it once it is shipping!), please
send email.  If I've heard from you, I will notify you by email once the
package is ready.

Let me know what you think!  Dan ([e-mail])



            PRE-RELEASE NOTICE FOR "THE DIGITAL UNIVERSE"
                           1995/05/31

This is an official pre-release notice for the software package
entitled "The Digital Universe".  Since the software has not yet
been finalized, some of the details may change slightly before
its release.  However, as the software is in the final stages of
beta testing, the following information should provide a good
indication of what to expect in the final product.


CONTACT ADDRESS
---------------
Dan Charrois, President
Syzygy Research & Technology Ltd.
Box 75
Legal, AB
T0G 1L0
CANADA

Internet email: [e-mail]


PRODUCT DESCRIPTION
-------------------
In a nutshell, "The Digital Universe" is a complete astronomy program
for the amateur or professional observer.  It combines the advantages
of traditional "planetarium" programs with a massive hypertext multimedia
encyclopedia to create an effective tool which assists the user in
observing and learning about the heavens.  50,000 lines of code, more
than 500 pages of hypertext, and thousands of man-hours have gone into
this product to make it the most complete program of its class.  The
software would not have been possible without the generous assistance
of many individuals from the Canadian Space Agency, the National Research
Council of Canada, NASA, JPL, the European Space Agency, the Bureau des
Longitudes, the Smithsonian Astrophysical Observatory, the Russian
Academy of Sciences, and several other organizations worldwide.


PRODUCT FEATURES
----------------
The following features by no means summarize all the things which
the software is capable of.  Due to space considerations, only the
major features can be summarized here.

- The following databases are integrated into the software:
    1.  Yale Bright Star (YBS) Catalogue of 9110 stars.
    2.  Smithsonian Astrophysical Observatory (SAO) Catalogue of over
        250,000 stars.
    3.  Messier's Catalogue of 110 deep sky objects (galaxies,
        nebulae, and clusters).
    4.  Sky & Telescope's NGC 2000.0 Catalogue of 13226 deep sky
        objects.
    5.  Tom Lorenzin's "1000+" database of observing comments for
        over 2000 objects.
    6.  Jost Jahn's comet database containing 2298 cometary orbits.
    7.  Jost Jahn's minor planet database containing orbital
        information for 27,715 asteroids.

- The software can generate accurate views of the night sky for any date
  from 100,000 BC to 100,000 AD.

- The user can select whether or not they want to consider effects such
  as precession, proper motion, nutation, aberration, or refraction,
  improving calculation times on slower machines.

- Uses the latest analytic theories of motion for the planets (VSOP87)
  and their satellites, resulting in typical accuracies of better than
  1 arcsecond.

- The current analytic theory of motion for the moon (ELP2000-85) has
  been extended to improve its accuracy even further for times within
  a few hundred years of the present.  The extension was done specifically
  for "The Digital Universe".

- Context-sensitive help system, linked into the online encyclopedia.

- Maps of Venus, the Moon, Mars, Jupiter, and Saturn are incorporated
  into the software to generate accurate renditions of the appearance
  of these objects when the user zooms in sufficiently to see their
  disk.

- Unlike many other astronomy programs which only consider the four
  brightest satellites of Jupiter, "The Digital Universe" accurately
  computes orbits for the moons of:
     Mars:    Phobos and Deimos
     Jupiter: Io, Europa, Ganymede, Callisto, Amalthea, and Thebe
     Saturn:  Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Hyperion,
              Iapetus, Phoebe, Telesto, Calypso, and Helene
     Uranus:  Miranda, Ariel, Umbriel, Titania, and Oberon
     Neptune: Triton and Nereid
     Pluto:   Charon
  When the software is zoomed in sufficiently to the planet of
  interest, the moons are rendered in their proper positions.

- The ring systems of Saturn and Uranus are rendered.

- When zoomed in to most planets and satellites, the object's
  orientation is determined and a latitude/longitude grid superimposed
  if the user desires.

- Supports the Amiga preferences printer.  Plots of star charts, etc.
  are far more than a simple screen dump.  The maximum resolution of
  the printer is used for outstanding clarity.

- The user can enter his or her own horizon, if desired.

- The user can select their location from a list of over 1000 cities,
  or enter their latitude, longitude, and altitude above sea level
  manually if higher accuracy is desired.

- The screen may be saved as a standard IFF picture file, and as such
  can be imported by a wide variety of paint programs.

- Completely user-configurable IFF animations can be generated.  This
  is really one of the more powerful features of the software.  Just to
  mention two examples from the infinite number of possibilities, you
  can see how stars move and constellations distort over centuries, or
  view how Saturn's rings change their orientation and appearance over
  time.

- A report generation feature lets you choose between a wide variety
  of data and customize tabular reports.  They may either be printed
  or saved to disk.

- Provided that you have sufficient chip memory, the screen upon which
  "The Digital Universe" runs can be of any size.  If the screen is
  larger that can fit on the monitor, you can scroll around simply by
  moving your mouse to the edge of the visible area.  A screenmode
  requester is provided to allow users to specify their particular
  monitor.

- All development was done entirely on Amiga.  It is not a port from
  the IBM or Macintosh world.  As a result, the software closely
  adheres to the Amiga style guidelines and behaves in the manner you
  would expect from Amiga software.

- Over 500 pages of hypertext, including an introduction to astronomy,
  dictionary of terms, biographies of famous people, celestial object
  descriptions, and summaries of every interplanetary spacecraft launched
  to date.

- More than 250 pictures are linked into the hypertext encyclopedia.
  They include images of all the planets, most of their satellites, all
  of the Messier objects, some NGC objects, and many miscellaneous
  images.  A few audio clips are incorporated as well.


CURRENT STATUS
--------------
The software is now in the final beta testing stages.  Once the bugs
have all been eliminated and the user manual written it should be
ready for release.  If all goes well, I am hoping that it will become
available in a few months.


PLATFORMS SUPPORTED
-------------------
The software will run on any Amiga with Workbench 2.04 or greater, and
at least 2 megabytes of memory and 10 megabytes of hard drive space.
A math chip (FPU) is recommended but not required.  Three versions of
the program are supplied in the package to make the best use of
different architectures:
  1.  68000-based Amigas
  2.  68020-based Amigas (or better) without an FPU
  3.  68020-based Amigas (or better) with an FPU

For customers with platforms other than the Amiga, an IBM port is
currently in progress and a Macintosh port will commence once the
Amiga version is released.


ESTIMATED COST
--------------
It is hoped that packaging costs will be kept low enough so that the
software can be sold for $99.95 in Canadian funds or $79.95 in
U.S. funds (plus shipping and handling).  In addition, a printed
version of the hypertext encyclopedia of astronomy will be available,
but the expected cost is unknown at this time.


FURTHER QUESTIONS?
------------------
If you have any further questions or comments on "The Digital Universe",
do not hesitate to contact me, either by regular postal mail or email.
You can find my contact addresses at the beginning of this document.