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Starry Night: Deluxe and Pro

by David. L. Harris

Washington Apple Pi Journal, November-December 1999, pp. 30-32, reprint information

In the September/October Journal I described how to track spacecraft with Starry Night Deluxe. When at MacWorld Expo in July I mentioned to a Sienna Software representative that I had written that article, I was given an evaluation copy of the new Starry Night Pro. Pro is sort of an industrial-strength version of Deluxe. This article will describe a few differences I have found between the two programs, although it will not be a thorough review, as I have not fully explored either program (and probably never will, considering how much there is to explore).

Pro vs. Deluxe

Figure 1: basic Hertzsprung-Russell diagram

Starry Night Pro has complete Hipparcos and Tycho stellar databases, which include star properties that Deluxe does not include; this makes possible displaying the Hertzsprung-Russell diagrams (about which more later) for stars in the field of view in Pro. Pro includes more Earth satellites, comets (but not Halley nor Hyakutake&endash;I suppose they were more in the news when Deluxe came out), and asteroids than Deluxe. Because Pro uses text files for data rather than Deluxe's proprietary format, it has the ability to update orbital information for multiple objects from widely available sources, rather than only making it possible to manually update them one-at-a-time, as with Deluxe. The Planets palette in Pro is more conveniently organized than in Deluxe: when you add interplanetary spacecraft, they go automatically into a (solar) "Satellites" folder. If comets are added they go into the Comets folder. Pro allows you to import pictures of deep-space objects, which will automatically size to fit into its sky view. You can view not only from the vicinity of the solar system, but also from anywhere up to 20,000 light years from it&endash;that's a good fraction of the galaxy radius. Printing charts is said to be more advanced. The local scene that appears in your Earth-based viewing window is more customizable. Pro requires a PowerPC, although Deluxe does not.


Back to the past

Readers of my earlier article may remember that the prediction made by Starry Night Deluxe of the time of the spacecraft Cassini's encounter with Earth, as seen from my vantage point at 25 AU north of the sun, was several hours later than the Jet Propulsion Laboratory's prediction and actual time of flyby. I had thought this was due to my data being obtained before the occurrence of most of the mid-course corrections (rocket firings) to be made to Cassini's trajectory between its Venus and Earth encounters. However, with later and later data, Starry Night's predicted time did not change much. Then I discovered that if I changed the observation point to Earth or to Cassini, Starry Night's predicted encounter time was very close to the actual time. I did not understand the difference until I got an e-mail reply from Tom Andersen, one of Sienna Software's people. He explained that Starry Night took into account the finite speed of light, and that my observation point at 25 AU away from the event meant that it would be seen there more than three hours later, the time it takes for light to travel that distance. It was something that had not occurred to me, and I did not know that Starry Night would take it into account. But it must do so if it is to give an accurate portrayal of events from any point in space!


Here are some of the differences between Pro and Deluxe that I noticed.


I personally found the printed manual that came with Deluxe, where it covered the same topics as the one that accompanied Pro, generally to be easier to understand. Somehow Deluxe's explanations were more straightforward and better-illustrated. Pro's manual also had a mistake in describing the Time functions; that will probably be corrected in a future manual.

H-R diagram vs Mouse tools

In Deluxe the tool window has a Mouse tool that shows position and other information for the onscreen cursor. As you move the cursor, this updates. Pro has no such tool; it is replaced by a Hertzsprung-Russell tool. Some of the pointer information is available in other ways in Pro, but not in such an easily-seen fashion (as far as I explored). A Hertzsprung-Russell diagram is a plot of absolute magnitudes (intrinsic brightness) versus temperature (or spectral color) for whatever stars are within the field of view. Danish astronomer Ejnar Hertzsprung and American astronomer Henry Russell discovered that a pattern emerges when you plot star properties this way. Most stars that we see in the night sky fall along a specific region of the H-R diagram called the "main sequence." See Figure 1, where the main sequence runs diagonally from lower center to mid-upper left. Cooler, redder stars are to the right; brightness increases towards the top. Other stars fall outside the main sequence; they may be red giants, white dwarfs, or other oddballs. Astrophysicists have developed theories which predict the "travels" of stars within a H-R diagram during their lifetimes; the courses they will take depend on their masses, and to some extent on their compositions, when they were first formed. Average, ordinary stars such as the sun will mostly stay on the main sequence, until very late in their lives, while other stars will rapidly move off of it into regions where they are less stable.

Figure 2: H-R diagram for nearby stars (Capella)

In order to put a star in its place on a Hertzsprung-Russell diagram, you must know its spectral type (from the spectrum of its light) and absolute magnitude (brightness). To know its magnitude, you must know how far away the star is, since only then will you be able to determine its intrinsic brightness from how bright it appears from Earth. Determining, or estimating, distances in space is not easy, nor entirely reliable; it gets harder the farther the object is from us. Only with the large database of star properties obtained with detailed surveys, which Starry Night Pro has, can a H-R diagram be shown.

The Hertzsprung-Russell tool in Starry Night Pro produces more than just a static diagram. Figure 2 shows a H-R diagram for all the stars within 50 light years of the sun; when you click on a star shown in the window on the right (Capella, in this case), that star's location in the H-R diagram is shown (on the left) by a red dot. Conversely, if you click on a dot in the H-R diagram, a red circle will flash a couple of times around the star in the picture to the right. You can see that Capella is not a main sequence star. Figure 3 shows that our sun is.

I am not sure how I feel about the replacement of Deluxe's mouse tool by Pro's H-R tool. It seems to me a rather esoteric item for most people who will use the program. I thought it might be useful to show the differences in star populations between a wide field of stars and something like M13, the globular star cluster in the constellation Hercules, as seen from Earth. That is because a globular (globe-like) cluster might be expected to consist of stars all formed at about the same time, and having similar histories. Such a group might have a different (and more uniform) spectral signature than an average field of stars. With this in mind I tried to examine the H-R diagram of M13 in Starry Night Pro, by zooming in on it to exclude other stars from the field of view. No diagram. Why? Because M13 in Starry Night Pro, like other such objects, is a picture. There is no star information in it. Arg.

Figure 3: H-R diagram for nearby stars (sun)

QuickTime movies

In both Pro and Deluxe you can create QuickTime movies, and choose among several varieties of compression modes (or none) to make the resulting movie files smaller. However, with my copy of Pro, the two Intel modes have problems (confirmed by Sienna Software, at least for QuickTime 4). When you choose an area of the screen to turn into a movie, the actual area captured in the movie is offset to the left of what you chose, so much so that if your area is too small, the object you thought you were filming is entirely offscreen to the right. In addition, those two compression modes produced false colors. No such problems were evident with Starry Night Deluxe. The solution in Pro, until Sienna fixes it, is to use another compression method, of which there are several.

Another QuickTime movie change is that, in Deluxe, movie preferences, where you select the compression type as well as several other parameters, is accessed simply by double-clicking on the movie tool. In Pro, by contrast, doing that selects the entire front window as the subject of a movie. To change movie parameters you must go to the File menu, to Preferences, to Movies… in order to change settings. It is not as convenient, especially when you are testing different compression modes to determine the quality of the resulting movies.

Satellites up close

Starry Night Pro comes with a large complement of Earth satellites already installed. If you select Mir (with the original satellite text file in Pro's Data folder) and zoom in on it, you will see a nice picture of that soon-to-be-history space station. You cannot observe the station from different angles, though. If you select the new ISS (International Space Station) you will see a nice picture of it. But if you select any other satellite and do the same, you will see the same ISS picture. Evidently Pro only has two different pictures of Earth satellites.

Incidentally, if you observe the Earth from a few thousand kilometers, and let the time run, many little blue dots (satellites) will be seen orbiting. It is amazing how many of them there are!


These are just a few of the areas of Starry Night Pro where I explored and found differences with Starry Night Deluxe. Three versions of Starry Night are actually available: Basic, which can be downloaded from <http://www.siennasoft.com/>, Deluxe, and Pro, both of which come on CDs. If you have a PowerPC, and are willing to spend the extra money, you should buy Pro. Although I found a few bugs, and a few places where its interface didn't suit me as well as Deluxe's, if you had never seen Deluxe you wouldn't even notice those. And Pro includes more data and has more capabilities than Deluxe. Basic's list price is $34; Deluxe is $89.95, Pro is $149.

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Revised November 24, 1999 Lawrence I. Charters
Washington Apple Pi
URL: http://www.wap.org/journal/