Astronomy Buddy is an iPhone or iPad app that describe itself as “the ultimate tool” for learning about astronomy as well as a helper for teachers. It includes lessons, quizzes, news feeds, astronomy videos and maps to the major observatories. However, the visual presentation and depth of explanatory material are not well matched.
The Home Page
The home page is a graphic with text in purple instead of black. There is a list of major sections, but no preference in the app or in iOS Settings. That means that there’s no way to turn off the beep every time you touch a section. Also, the Next button on the upper right of the home page doesn’t do anything.
An obvious first place to look is the “Astronomy Lessons,” marked with a film icon, but the lessons are all text and static graphics.
I started by looking at the chapter “The Sky,” and the first thing that I noticed in the discussion of stellar magnitudes was the fact that exponents are not raised. So for example, instead of 2.5125 = 100, the text shows (2.512)5 = 100. That looks like a multiplication. Throughout the app, I could not find any place where the exponents were raised, leading to expressions in chapter 6, “Light and Telescopes,” such as “c = 300,000 km/s = 3*108 m/s.”
The next chapter I looked at was Chaper 3, “The Cycles of the Moon.” On the page “Phases of the Moon,” there was this illustration:
which is technically correct, but has a lot of visual clutter that obscures the essential dynamics.
In the chapter 5, on the page “Velocity and Acceleration,” the idea is that acceleration is a change in velocity over time. The graphic, with presumably Galileo, suggests that he is trying to solve for “a.” In this case, the (relative) constant 9.8 m/s2 near the earth’s surface. With an instructor providing insight, all would be well. But for the student working alone, there is a flood of hidden assumptions: an implicit notation, in bold, of vectors (not explained) along with calculus (not introduced). The customary approach is to start with v = gt, let the student do some computations, get a feel for acceleration, then intoduce calculus and vectors.
Moving on to the page on gravity, there is once again a failure to handle exponent of “r” correctly plus a minimum of explanation. For example, the minus sign isn’t explained. Why F and G are in bold but the masses are not and what the direction of the force is isn’t explained.
In the section on “Orbital Motion,” again, there is a diagram with not a lot of underlying explanation. The symbols v and v’ aren’t defined, and the vector Dv isn’t isn’t clearly related to the gravitational force previously defined.
On the page “Kepler’s Third Law Explained by Newton,” the discussion for Kepler’s 3rd law, has a formula, intended to describe how the period of a planet squared is proportional to the semi-major axis of the orbit cubed, normally written as p2 proportional to a3. Below is how the app presents it. And the promised connection to Newton doesn’t appear.
The offset box looked exactly the same on an iPad 2. The author is trying to convey the idea that the period (P) squared in years is equal to the semi-major axis in astronomical units (AU) cubed. There’s no explanation of why the proportionality constant goes away in those units. The marred visual presentation, with typographically misplaced exponents and no deeper explanation, leaves all that out.
This style of intense graphical presentation combined with sparse, PowerPoint-like annotations is continued throughout the app. As a final example, amongst many, the chapter on “Stellar Evolution,” has a page “Evolution on the Main Sequence. The chart’s accompanying text of why stars move off the zero-age main sequence of the Hertzsprung-Russell diagram, or the direction they take, as they age doesn’t doesn’t provide the promised insight.
Assuming that the student works through the material on stars, the family of stars, the formation of stars and stellar evolution, here’s an example of what the author calls a fun quiz.
Another area I explored was “Astronomy News,” and then Stargazing for beginners. Once gain, the app presents purple text on a light blue background with dark blue highlighting, like this.
I selected “How to Chose Binoculars for Astronomy,” and the result was a broken link, a 404 error.
All of the other items of that page that I tested had broken links as well. The app was released on March 29, and no updates since then have fixed the links.
One of the pages on the home screen offers to show device info. In my case, the primary testing was done on an iPad 3 which has a resolution of 2048 x 1536 pixels. The app says otherwise.
Another item on the home page is an entry for “Email Us,” which appears to be an invitation to email the developer. I tried that, and got this auto-fill mailer with an addresse of “[email protected]”. I was expecting the To: field to contain “[email protected]”
I experienced frequent crashes when moving between sections.
Compatible with iPad, iPhone, iPod touch. Requires iOS 3.0 or later.
In summary, I cannot recommend this app in its current state at version 1.0 for the student. Instead, I recommend any basic astronomy textbook, some of which can be found used for under US$10. This app might serve as a template for a professor teaching an astronomy class who doesn’t already have a curriculum and intends to fill in the details and insights.