Updated 5 June 1998
NOTE: The information on this page is somewhat dated (as of Nov 2002), the software packages covered have been superceeded by newer versions. I am keeping this info available as a historical archive.
This page will contain review comments on astronomical software packages that I (Joe Roberts) own. Currently I own only two packages: Star Traveler and Redshift 2.
As most people know, the performance of a particular piece of software is related to the hardware it is running on. Thus, I will describe the computer I use the software on; this will help to establish what you might expect if you have a different system:
Below is a list of astronomical software packages for which comments are written:
Star Traveler is the first astronomical software package I have ever owned. I received it as a Christmas gift.
Star Traveler is "Limited Edition Astronomy Software" from the Nature Company. It is based on Meade's software "The Sky". The version I have is "version 1.0".
By most standards, Star Traveler is a basic program as compared to the capabilities of most other astronomical software. It comes on two 3 1/2" floppies (hence indicating its relatively limited capabilities).
When started, Star Traveler puts up a display of the sky (based on the compute's system time) on the screen. Stars, planets, the Sun and Moon, along with a number of deep sky objects are shown. The default screen is in "Night Vision" mode (dark background with white stars). By moving the mouse to an object and "clicking", a window appears and displays data on the object. Among the data are the name of the object, magnitude, coordinates, rise, transit and set times. For solar system objects, angular diameter, phase and distance (from Earth) are also given. For deep sky objects, size is given and a "common" name if the object has one. When clicking on a subsequent object, the pop up window will also show the angular separation between the current object and the last object. I find this useful to determine the angle between the Sun and Moon for example.
Star Traveler seems to have stars down to about magnitude 7 (the package does not provide any details on this). The number of stars displayed is "zoom dependent", meaning that as one zooms in on an area, more stars will appear (and vice versa). Star Traveler seems to display a remarkable number of deep sky objects (especially galaxies) for a package of this relative simplicity. The number of galaxies shown on the screen is zoom dependent. When zooming in to a field width of about 5 degrees, galaxies as faint as magnitude 15 are shown! Star Traveler appears to have many more galaxies than Wil Tirion's Sky Atlas 2000. I have noticed that not all of the galaxies display a pop up window containing information (this is true for the faintest galaxies). A message sometimes pops up and states that no info is available for Object NGC xxxx.
Star Traveler has a number of options as to how various objects and graphics may be displayed. There is a "chart mode" and "night vision mode". In chart mode, the screen looks very much like the deluxe edition of Sky Atlas 2000. The operator is able to change the color of constellation boundary lines, constellation lines, gridlines and object labels. The user has the choice as to whether or not to display object names, constellation names, etc. One thing that can't be changed is the depiction of deep sky objects. In the "Night Vision Mode", galaxies are VERY hard to see (red ovals on a black background) unless the view is "zoomed in". They are very easy to see when in "Chart Mode".
I find that Star Traveler is very easy to use; one can pretty much find their way around just be doing the obvious. There is a "control bar" which contains buttons to display (or not display) stars, deep sky objects, constellation lines, boundary lines, grids, etc. Also, zoom in/out controls and "move" buttons are displayed, along with the usual printing commands. I find that Star Traveler generates pretty nice charts overall. The only drawback is that only a very few deep sky objects are identified (you have to "click" on them to bring up the data).
Star Traveler provides no data as to how far back (or forward) in time the program is "good" for. For kicks, I set in the date, location and time for some solar eclipses between 1970 and 1994. I found that the program seemed to be very reliable over this (admittedly small) range. I have done some random comparing to the output generated by Redshift 2 (which is good for 4700 BC to 11000 AD); in general the programs seem to agree for events within the last few hundred years. When I punched up the 10 May 1994 Annular Solar eclipse, Star Traveler clearly showed the Moon being smaller than the Sun (when zoomed in enough to show the true sizes of the Sun and Moon), just as I saw it for real in Vermont!
Star Traveler contains a feature that allows one to generate (and print) Moon phase calendars, and also has a "Jovian Moon" feature. I find these to be nice additions. The Jovian Moon feature allows one to watch the motion of Jupiter's 4 Galilean moons for a variety of input parameters.
One of the nice features about Star Traveler is that it is super easy to use (primarily because it is a basic program). The displays are pleasing to the eye. I have long since explored all of its capabilities, but it is still a program I have "running in the background" almost anytime my computer is on. I find that I have a much better awareness of the positions of solar system objects since I started using this program (even during the day, when it's cloudy, or whenever!). I like to watch the Sun occult 7th magnitude stars along the ecliptic... without optical aid or protection! Most users will probably quickly outgrow this program (it made me thirsty for a program with more power). However, I do use it most often because it easily fits entirely on a hard drive, and loads and runs very quickly. I feel Star Traveler is an excellent "first" program. I would predict however that most users will want to obtain a more powerful program after playing with Star Traveler.
NOTE: My version of Star Traveler (v1.0) has a "bug". When I change the "date/time" setting the first time, things work OK. If I try to change it a second time, the program nearly always displays the message "Stack Overflow" and termination of the program results. So, those who say "don't buy version 1.0 software" are right!
Update for 5 June: I have noticed that Star Traveler does not generate a "stack overflow" error on another computer I use. However, that computer has 96MB of memory! I believe that the problem lies with the program... a relatively simple and small program like this could not possibly require 96MB of RAM to work properly!
Star Traveler was purchased via mail order for $29.95.
This review is not yet complete. Redshift 2 is a very powerful software package; it will take me some time to write up all of its features... it has taken a while to explore them all! Not to mention, Redshift 3 is now available...
Bugs: My version of Redshift 2 has a few bugs that I have located. Number 1: The Great Nebula in Orion, M42, is not plotted on the display! Number 2: The bright star Sirius is not plotted on the display! How these two major items got left out is beyond me (the data is all there for both of them... they just don't show up on the charts!) Weird...
Comments thus far on Redshift 2: Redshift 2 is a very powerful software package. It operates over the date range of 4700 BC to 11000 AD. Using Redshift 2, you can place yourself on any star, planet or moon in our solar system! You can even place yourself on some asteroids and comets. Not only that, but you can place yourself in most any position on the previous listed objects... position being defined as long, lat and height! Redshift 2 is amazingly versatile in this regard.
Often, Pete and I (the authors of these pages) receive questions via e-mail concerning various astronomical events. I have used Redshift 2 on several occasions to answer the questions. As part of this review, I will use some of the questions received to help illustrate by example the capabilities of Redshift 2.
Question: I was hoping you could answer a question for me: on what date in 1999 will Pluto once again become the outermost planet? I know that Neptune and Pluto are currently in the approximately 20 year period when they are switched. Also, if you could give me the date in 1979 that Neptune became the outermost planet, I'd be most appreciative.
Answer: Redshift 2 cannot spit out this information directly (to my knowledge). However, Redshift 2 does provide detail on any planet when the planet is "clicked on". Among the substantial data provided is heliocentric distance (distance from the Sun) in AU (this distance is provided to an accuracy of 6 decimal places!). Armed with this knowledge, the method to answering this question became clear... simply find the dates when Pluto and Neptune had equal heliocentric distances! Knowing that the dates were in 1979 and 1999 gave me the two starting points. I arbitrarily picked a date in 1979 and then entered this date info into Redshift 2. I then used the "Find Object" feature to find Neptune and then Pluto. For each planet I noted the heliocentric distance. I then picked another date about a month different from the first and entered it into Redshift 2. I then located each planet once again, and noted the heliocentric distance for both. Once I had this information, I could tell if I was "moving away" from the desired date or closing in on it. I then picked other dates and by "process of iteration" zeroed in on the date when Neptune and Pluto's heliocentric distances were equal. The date in 1979 turned out to be 2-8-1979 at 14:32 UT (Julian day 2443913.1056). I ran through the same process to find the date in 1999 when Pluto and Neptune again had the same heliocentric distance. This date turned out to be 2-9-1999 at 7:20 UT (Julian day 2451218.8056). This basically means that Pluto was closer to the Sun than Neptune for almost exactly 20 years! Although Redshift 2 could not directly provide me the answer to the reader's question, it provided me with the tools to obtain the answer.
Redshift 2 can search for conjunctions of any planet, the Earth's Moon, or the Sun (a conjunction is a close grouping of objects in the sky). Redshift 2 allows the user to pick the objects to be included in the conjunction, the dates over which to search, and the distance range (up to 9.99 degrees) of the conjunction. For example, a user could ask Redshift 2 to create a list of all the conjunctions of Jupiter and Saturn that are 3.4 degrees or closer between the years 1700 and 2000. Redshift 2 then creates a table listing all of the events found (if any). The data in the table includes the date, time and the separation of the event. The user can then "click" on any event in the table, and Redshift 2 will display the event! This is a very handy and powerful feature in my opinion. Although most people are interested in conjunctions that can be seen from Earth, Redshift 2 can search for conjunctions of objects as seen from any planet, moon (or the Sun) in the solar system. As an example of the power of Redshift 2, consider the question sent in by another reader:
Question: I'm writing a story which takes place about 2050. Can you tell me what year (sometime around the middle of next century) there will be a relatively close alignment of Jupiter, Saturn, Uranus and Neptune with the Earth?
Answer: Redshift 2 can fairly easily nail this down. The person who sent in the question did ask for Earth, but because Earth's orbit around the Sun is rather small compared to that of the remaining planets listed, the Earth's position for all practical purposes be ignored (Earth will always be in a "relatively" straight line with the outer planets if they happen to line up). The reader asked for a "relatively close" alignment of the 4 major outer planets around the year 2050. The "determining factors" here are the orbits of Uranus and Neptune... they move rather slowly and hence "line up" roughly once every 200 years! Since we just went through a Uranus-Neptune encounter in 1993, another one will not be along for quite some time. Nonetheless, let's go ahead and enter the information into Redshift 2. Under the "Events: Conjunctions" feature, we select Jupiter, Saturn, Uranus and Neptune as the planets to be included in the conjunction. We'll set the distance (between the objects in the conjunction) to the maximum of 9.99 degrees (because close alignments of four planets simultaneously are extremely rare). We'll set the dates over which to search from 2000 to 2100 AD. The result? Redshift 2 finds no events meeting our criteria in the time span specified! This could have been "guessed" however, knowing that Neptune and Uranus are more than 10 degrees apart in 1997 (and moving father apart for a long time to come). What now? I decided to search for conjunctions with Jupiter and Saturn (the two major planets), and then "go looking" to see where Neptune and Uranus were at the times of those events. The results:
So, based on the maximum amount of separation that Redshift 2 considers a conjunction, there were no events that met the criteria of the person who submitted the question. However, Redshift 2's controls allowed me to "look and see" where the other planets were at the time of conjunction of the major planets Jupiter and Saturn.
More to come on Redshift 2... it's a great program with very powerful features. It will take me a while to write this up. Want the "quick review"? A great program!
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