This page contains answers to the most frequently asked questions about SkySafari for Android.
Where can I buy it? Can I get a free copy?
Right now, SkySafari is exclusively for sale on Google Play Store.
SkySafari is not shareware or freeware. If you downloaded our app from a warez site and you did not pay for it, please know that you are pirating our work, which is very discouraging for us. Please consider that we are a small company; we work hard to develop and support top-notch software on the Android platform, and that we make a living from our products.
We hope that our apps provide you with great value for the very few dollars you've invested in them.
I tried to buy your app, but Google Play says my Android tablet or phone is incompatible. Is there any other way I can install your app on my device? Can you give me a copy?
No. There are thousands of different kinds of Android devices out there. Google probably doesn't know about yours yet; that's why it's listed as incompatible. But the problem is larger than that. We do most of our testing on "mainstream" Android devices, such as sold by Google, Samsung, Motorola, and HTC. If you stick with mainstream brands, our apps will probably work well on your device.
We receive the vast majority of our problem reports from people using cheap off-brand Android devices. The bottom line is that you get what you pay for, and if Google Play doesn't support your device, we won't either.
If I buy the basic version now, can I upgrade to the Plus (or Pro) version later for just the difference in cost?
No. These are separate apps on Google Play. Google does not credit the purchase of any app toward the purchase of any other. Remember - you're actually buying the app from Google, not from us. If you want a refund for your purchase, you need to contact google - we cannot issue Google Play refunds directly.
It's for this reason that we've kept the basic version of SkySafari as inexpensive as it is. If you decide that you want to upgrade to Plus or Pro later, make sure you know which one you want. This is a purchase decision which we cannot make for you, and which we cannot reverse.
I own more than one Android device (or I bought a new one). Do I have to re-purchase it for each device?
No. SkySafari uses standard Google Play licensing. You can install it on as many Android devices as you have linked to your Google Play account.
When the app starts up, I get a message that says "License Verification Failed," then the app exits. Can you fix this?
No, we can't. We're using Google's own license verification library code; unfortunately, sometimes Google's servers are just flaky. If you are having this problem, our best advice is simply to wait a few minutes, or up to an hour, and try again later. Or to try it from a different internet or Wi-Fi connection. Make sure your Android device is connected to the internet when you run the app for the first time!
This problem seems to affect a small number of folks. Usually this is caused by either:
Occasionally, you may need to uninstall and reinstall the app for license verification to proceed. We are not sure why this happens, but it seems to be something amiss in Google Play.
The other possible solution is to delete the Data for the Google Play app using the Android Settings app. Then run the Google Play app again and let it rebuild its data correctly. You will need to re-accept Google Play's license agreement when doing so. This seems to fix many of the license verification problems.
Please let us know if the problem persists. It does seem to eventually work correctly for all users.
After the license has been verified, you will not need internet access for verification again unless you reinstall or upgrade to a different version.
No. SkySafari for Android is a complete rewrite of app, written in a different programming language, running on a device with a different kind of processor, under a separate operating system with a different user interface. Our Mac and iOS apps are sold through different app stores. Even if we could offer you discount, there's no way we can do so.
We hope that this won't dissuade you from purchasing our Android version separately. Most desktop astronomy programs competing at SkySafari's level of sophistication cost hundreds of dollars - ours is priced, like our iPhone apps, at the cost of a pizza. At these very low prices, we hope that SkySafari for Android will provide you with tremendous value, in spite of being a separate purchase.
What Android OS version do you require? What are your hardware requirements?
SkySafari for Android requires Android version 4.0 or later, running on an Android phone or table with a 1 GHz or faster processor. It may run on slower devices, but performance will be extremely sluggish.
SkySafari requires a Google Play account, and will not run on devices which do not have Google Play access.
Will it run on Android tablets?
Yes, SkySafari for Android will run on tablets as well as phones, and will use the entire tablet screen at full resolution. Some functions - e.g., ability to provide a live view of the sky using the compass and accelerometer - may not work on low-end Android tablets (e.g. the Kindle Fire) or other Android devices which are missing the required hardware.
How about the Kindle Fire?
SkySafari will run on the Kindle Fire if you have modified it to use the Google Play store.
Does it have the same features as your iOS version?
For the most part, yes. All major functions and features in the iOS version are also be available in the Android version. As per above, some features may not be supported on low-end Android devices which lack the hardware required to support them. Some "look-and-feel" touches - animations, panning to objects, pulsing selected object markers, etc. - may not be present in the Android version.
The general layout and organization of SkySafari for Android is very similar to SkySafari for iOS. But our Android version has an Android "look-and-feel", and conforms to Android OS standards.
How is your app different from Google SkyMap? Why should I pay for it when Google SkyMap is free?
For starters, even the basic version of SkySafari includes ten times more star data than Google SkyMap. Our deep sky database contains thousands of NGC/IC objects, not just the 110-object Messier catalog. Our Pro version contains about 628.000 solar system objects - including every known moon, asteroid, and comet in the solar system - not just the Sun, Moon, and nine planets (we're sentimentally still counting Pluto!)
Our apps contain hundreds of built-in images, and include thousands of object descriptions, written by professional astronomers. Google SkyMap gives you Wikipedia links - which don't do you much good when you're out in the field, away from Wi-Fi or data network connections.
Our Plus and Pro versions can control telescopes; Google SkyMap cannot - nor can any other Android app, as far as we know.
Google SkyMap cannot reproduce basic astronomical phenomena like lunar eclipses and Jovian satellite shadow transits. That's OK - Google SkyMap is a publicity tool for a company (Google) that makes nearly all of its revenue by selling on-line advertising. Our apps, by contrast, were developed by passionate astronomers with a penchant for quality and accuracy. We make a living from our products, and we stand by them.
If these things don't matter to you, or if $3 seems too high a price for them, then by all means, get Google SkyMap.
My Android device's SD card is nearly full, but my device has another external SD Card. Can I install the extra data onto my external SD card instead?
Not at this time. Google Play automatically downloads SkySafari's extra data to the internal SD card; the location is not configurable. We are looking at alternate ways of solving this problem. In the meantime, you may be able to solve the problem yourself, by moving some other apps, movies, songs, etc. from your internal SD card to your external SD card and freeing up some space.
Is your Android version slower than your iOS version? If so, why?
The code which computes the positions of the stars and planets, and renders the sky chart onto the screen, is exactly the same as our iOS code. It's line-for-line identical C/C++, using exactly the same OpenGL graphics calls. Yet this code tends to run slightly faster on iPhones than Android phones. Obviously the exact speed difference depends on which iPhone vs. which Android phone you're comparing.
There seem to be two reasons for this. First, the graphics hardware build into iOS devices seems a bit faster than that built into most Android devices, particularly on the low end. Secondly, Android's software rendering pipeline seems to be less efficiently designed than that of iOS.
How about telescope control?
Yes! SkySafari for Android supports telescope control, both via Wi-Fi and bluetooth. Our SkyFi 3 wireless adapter is fully compatible with Android devices. Our SkyFi 2 wireless adapter does not work with most Android devices. Google has chosen to disable support for Ad Hoc WiFi networks, such as generated by our SkyFi 2 adapter, by default in the standard Android OS. You can enable Ad Hoc WiFi network support on your Android device, but you'll have to root the device to do it. Alternately, you can join both SkyFi 2 and your Android device to an infrastructure WiFi network, such as provided by a typical home router - but then you'll need to carry that router with you, and find a way to power it, when you go to your remote observing site.
We also offer telescope control in SkySafari for Android via bluetooth. This is something that isn't possible with iOS devices due to Apple restrictions. Our SkyBT bluetooth serial adapter is perfect for this. We can't offer support for every third-party bluetooth serial adapter on the market, but we've programmed SkySafari to use standard Bluetooth Android interfaces, so most should work. If you can configure your bluetooth adapter to control your telescope from a Mac or PC, it will probably work with SkySafari for Android. A list of bluetooth serial adapters that are known to be compatible, and not compatible, with SkySafari, is provided on this page.
My Android device has a USB port. Can't I just use a USB-to-serial adapter to talk to my telescope?
No. For this to work, your Android device would have to be a USB host, and most devices are USB slaves, not hosts. Secondly, your Android OS would have to be running the drivers for that USB-to-serial adapter. As of this writing, we don't know of a single USB-to-serial adapter manufacturer that produces Android drivers. You can root your device, write your own drivers, and recompile the Android kernel if you want to take a stab at this yourself!
The situation with Android USB-to-serial adapters may improve in the future, but we have no plans to support any telescope connections other than bluetooth or WiFi at this time.
I'm a geek. How did you port SkySafari from iOS to Android?
The main challenge was that native iOS apps must be written in C, C++, or Objective-C; whereas Android apps are written in Java. Fortunately, SkySafari's core "engine" code was already written in C/C++, and in 2010, Google offered a native development kit which allowed us to recompile that core engine code for Android. All of the code which computes planetary positions, reads star and deep sky data out of the database files, and draws the sky chart using OpenGL, is line-for-line identical to the code in the iOS version. This saved us from having to rewrite more than 168,000 lines of code in Java, and is really what made SkySafari for Android possible in the first place.
The other part of the app is, of course, the user interface - all of the buttons and menus and switches you can touch to control the app. While they might appear vaguely similar to those in iOS, the Android APIs (application programming interfaces) to those controls are completely different from those in iOS. For one thing, they're all written in Java, not Objective-C. So this part of the app was a complete, 100% rewrite.
Our first Android project was developed in conjunction with Sky & Telescope magazine. It was the Android version of the S&T SkyWeek app for iOS, released earlier this year. This was a relatively simple Android app, with a minimal user interface. This allowed us to concentrate on porting our underlying C/C++ engine code to Android, and prove the concept.
Rewriting all of SkySafari's user interface in Java took a lot longer but we feel it has come out well and the Android version of SkySafari is now just as good as on iOS.
Observing lists are cool, but creating them by hand is tedious. Can SkySafari import an observing list that I create as a text file, or an observing list from another program?
SkySafari does not support other programs' observing list formats directly. But in SkySafari Plus or Pro, version 1.1.1 or higher, you can import observing lists as text files. At least a few other programs (AstroPlanner, Deep-Sky Planner, Eye & Telescope) can now export observing lists to SkySafari in this format.
See the the section on Observing Lists in SkySafari's built-in Help file for instructions on how to import them into the program. Briefly: you can copy observing lists into or out of the SkySafari/Observing Lists folder on the root level of your SD card. You can also email observing lists to yourself, and open the .skylist file attachment from your Android email client (tho not all versions of Android support this feature.)
If you want to convert your own observing lists to a text file that SkySafari can import, here's an example of the format that you need to use:
Comment=Great red spot was great! And red!
Lines may be separated by a single linefeed (LF) character ('\n', ASCII hex code 0x0A, decimal value 10), or by carriage return (CR) characters ('\r', ASCII code 0x0D, decimal 13), or by CR-LF pairs. In other words, your text file may be a unix-style text file, or a classic Mac or DOS/Windows text file.
The first line must be
Observing list entries are groups of keyword=value pairs. Groups are demarcated by
In the sample above, we've indented the keyword/value pairs within each object for clarity, but you don't have to. SkySafari strips out leading whitespace when importing the file.
The ObjectID field is what SkySafari uses internally to identify the object. Since you don't know this, you can use the following:
1,-1,-1for solar system objects
4,-1,-1for deep sky objects
SkySafari will try to find the object based on the
CommonName values, and fix up the
ObjectID values internally after it imports the list.
CatalogNumber values are used preferentially instead of the name(s). Please use the same catalog abbreviations that SkySafari uses, e.g. Alpha CMa, HR 7001, M 97, NGC 1695. If the object has no
CatalogNumber (like Jupiter), then enter its name(s) in the
CommonName field. For asteroids, the asteroid number is the
CatalogNumber; use the
CommonName field for all other solar system object identifiers.
CommonNames you've specified to import properly. This is how SkySafari resolves ambiguities between diffiferent objects with the same name: for example, comet Garradd (C/2009 P1) vs. comet Garradd (C/2008 J5), or the asteroid Europa (number 52) vs. Europa (Jupiter's moon, no number). In most cases, though, only a single
CommonNameshould be required to uniquely identify the object.
Comment are optional.
DateObserved is the julian date on which your observation took place;
Comment is the notes you want associated with the object. Newlines in the notes should be indicated with a \n sequence.
How do I get my own horizon panorama into SkySafari? Can you show me an example?
Read the Help file included with the program, under the Settings > Horizon & Sky section! Briefly, first use a program like Photoshop to create a panorama from individual pictures. Your finished horizon panorama must be a 2048 x 1024 pixel image in PNG format, with alpha (transparency) indicating clear sky vs. opaque ground. North is at the left edge; south is in the middle. Connect your Android device to a computer with a USB cable, then copy your panorama PNG file into the SkySafari/Panoramas folder on the root level of your SD card.
Here's an example, sent to us with permission by Roger Greenwood in Massachusetts, USA. Click the preview image below to view the full-sized PNG, which you can import into SkySafari as an example:
Joshua Bury, creator of the Observer Pro iOS app, has created a web-based application that converts a numerical horizon representation (altitude/azimuth points saved as an Observer Pro .hzn file) into to a panorama that can be used in SkySafari. It's not as accurate as a well-done photographic panorama, but it is really easy to create, especially if you've used Observer Pro to measure your horizon.
The horizon is not visible! But I've got "show horizon and sky" checked, and/or a panorama selected, in my Horizon & Sky Settings. What's wrong?
If you're running SkySafari Plus or Pro, make sure your coordinate system is set to Horizon coordinates. Look in your Coordinates settings. If set to Equatorial, Ecliptic, or Galactic coordinates, the horizon will not be shown. This is deliberate - these other coordinate systems do not align to your local horizon, so it would appear skewed at a wierd angle. A printed star chart uses equatorial coordinates, and does not show the horizon either. SkySafari is no different.
The sky chart is covered with hundreds of labels for satellites/comets/asteroids, and I can't get rid of them! Is that a bug?
No, you have just turned on highlighting for an object list. Look for a small green list icon at the bottom of the sky chart, and tap it. That will bring up a menu with an option to show you to the object list that is highlighted. Switch off the hilighting, and the labels will go away.
This feature is intended to let you quickly see where all objects in a particular list - for example, Messier objects, or an observing list that you've created - are located in the sky. You might have highlighted that list by accident. The green list icon always brings you back to the list that is highlighted.
Can SkySafari compute the exact angular separation between two objects in the sky?
Yes! SkySafari Plus and Pro can do this, but the basic version cannot. There are two ways:
1. Tap the first object to select it, then double tap the second object. This turns on measurement mode. A blue line is drawn from one object to he next with the angular separation. Tapping and dragging on the second object will allow you to move the end point to another object. To exit measurement mode just tap anywhere else in the chart.
2. Select the first object by tapping on it or searching for it. Then select the second object (also by tapping or searching). Finally, tap the Info button on the main toolbar. The Object Info data table shows the angular separation from the 1st object to the 2nd object, and the position angle. It also shows the 2nd object's angular separation and position angle from the Sun, and from the chart center.
I've turned on Night Vision, but part of your user interface is still drawn in white. Can you fix that?
Possibly not. Making every Android user interface element red is actually very challenging; there are some things that Android does not give us any control over. For this reason, we always recommend using a sheet of red cellophane, like Rubylith, if you absolutely need every part of the screen to be red. And a "hardware solution" like this will work even if our app is in the background.
Some double stars don't show their companion when I zoom in. Why is that?
The only stars we plot on the chart are the ones in SKY2000, Hipparcos, and Tycho 2 catalogs (and GSC2, in the Pro version). If your star isn't in those catalogs, it won't be displayed.
The only exception to the above are stars whose primary is in the above catalogs which also happen to have orbits in the 6th Binary Star Orbit catalog. If that star has an orbit, and its companion isn't already obviously listed as a separate entry in SKY2000/HIP/TYC2, then we generate a separate binary companion for it.