Stargazing sessions with Stellarium Mobile
Posted by Greten on 02 Jan 2021 under Tools
About a decade ago, my recommendation for preparing a stargazing session was to print a screen capture of the digital star map, such as Stellarium, from your computer and bring the printed copy to the stargazing venue. I also recommended buying an almanac from the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) or whatever government agency manages astronomy research in your country.
Many changes have happened since then. First, the Philippines already has a separate agency called the Philippine Space Agency. Thus I have yet to check if such almanacs are still available and which government agency sells them. Second, Iphones and Android-based smartphones have so much increased usage that more people know are browsing the internet using their mobile phones. Many educational applications are now available for mobile devices. Stellarium and other digital star maps are now available for mobile devices. Hence, it can be more practical for most people to bring a mobile device with a digital star map application installed instead of printed copies.
Stellarium Mobile is free to install; hence, it's called Stellarium Mobile Free in Google Playstore. Once installed, you can upgrade to Stellarium PLUS, where additional functions and catalogs become available. Stellarium Mobile does not have all the functions of Stellarium in computers, but for the purpose of bringing a star map in an open field where stars are more visible, it is more than sufficient. I am not sure if these missing functions become available with Stellarium PLUS; I'll write another entry should I decide to purchase it.
To install Stellarium Mobile in Android, search "Stellarium" in Google Play Store. Stellarium Mobile Free will appear with several other digital star maps. Tap the "Install" button to install it.
Stellarium Mobile Free is apparently not available for Ios/Apple. To install Stellarium PLUS on an Apple mobile device (Iphone or Ipad), search "Stellarium" in Apple App Store and tap the price button (₱499.00 in the screenshot), proceed with the payment process, and install it.
Just a month or two ago, Google Playstore lists Stellarium Mobile Free and Stellarium Mobile PLUS separately. Yet, as of today, only Stellarium Mobile Free appears in search results of Google Playstore, with Stellarium PLUS available as an add-on after you installed the free version. A year ago, there are no Stellarium Mobile Free or Stellarium Mobile PLUS in Google Play Store; it only has Stellarium Mobile that is not free.
While Stellarium mobile does not have the full function of the Stellarium for personal computers, it is still a powerful application to help in stargazing. These functions are based on Stellarium Mobile Free for Android, v1.6.5.
Across the top of Stellarium's user interface is the Search function. Type the name of the celestial body and press the Enter key. Stellarium centers the view to the location of that celestial body with a white crosshair to indicate it, and a gray dialog box appears at the bottom with the name of that celestial body. Use the Zoom icons on the bottom right to zoom in to that celestial body to see it closer, or zoom out to see its immediate surrounding. You can also swipe up the gray dialog box to see more information about that celestial body, such as its visibility and current position.
When you tap the Search field, aside from being able to type, you also have the option to search the celestial body using the Browse by type function, which appears just after you tap the Search field.
The Menu options provide different functions, with many of them locked until you purchased Stellarium PLUS. Open the Menu options using the burger menu on the top left adjacent to the Search field. The options that are available for free are:
- Location: sets up the viewer's location. You can set it up manually, or you can have Stellarium copy the location of your phone.
- Sky cultures: provides information about astronomy and constellations of different cultures. Select a culture, and the constellations will change based on that culture.
- Settings: has only one option available, which is the Reset Settings. The other setting options are available only in Stellarium PLUS.
- Upgrade: opens the interface to upgrade to Stellarium PLUS either monthly on a subscription basis or a one time upgrade.
- Help & feedback: provide information about the current version of Stellarium, user guide, and links to contact the developers and provide feedback.
The viewing options are available through the icon that looks like a stack of two diamonds at the bottom left corner. Tap it, and the options that you can enable or disable become available at the bottom. The dialog box containing this icon occupies a large part of the user interface, so it's preferable to keep it close most of the time. To close the viewing options, tap anywhere on the screen outside the dialog box.
The viewing options available are as follows:
- Grids & Lines: enables the azimuthal grid. The equatorial grid, which is available in the computer version, is also available through this option but requires an upgrade to Stellarium PLUS.
- Constellations: displays the constellations. Tap to enable or disable. Long press to see additional options such as display lines, labels, boundaries, and drawings. I'm not sure what the Centered only toggle switch does.
- Landscape: displays the ground. Long press allows you to change the picture that appears as the ground.
- Atmosphere: shows the sky's color at a given time and makes celestial bodies invisible if they are really invisible due to the atmosphere. Additional options are available only on Stellarium PLUS.
- Labels: displays the names of stars and planets. Additional options are available only on Stellarium PLUS.
- Night mode: overlays the interface with a red tint to make it easier to view if the location of stargazing is very dark (e.g., middle of the field with no nearby light source).
You can display or disable a viewing option by tapping the icons. Long press an icon to see additional options for that viewing option; all viewing options except Night mode have additional options.
Projections of the sky
If you slide your finger on the main screen, different projections display. As you slide your finger, the change from one projection to another is continuous. However, depending on how you intend to use Stellarium, you can use three projections: horizontal projection, sky dome projection, and view from above projection. Enable Landscape to have a clear horizon and see these projections.
The horizontal projection mimics what you see on the venue of stargazing; the horizon is far and you need to "turn around" (i.e., swipe the view left or right) to see the stars at your back. However, there's still distortion; you can see three of the four cardinal directions within the same narrow viewing screen, which is not possible in reality unless you are using a fisheye lens.
To view Stellarium in horizontal projection, swipe up or down along the center of the screen until the horizon is a horizontal line or has the least curvature that you can have. You can do the following while you have this projection:
- Swipe left or right along the vertical center to see the stars outside the viewing field as if you are turning around. Try to stay along the vertical center as much as possible because slight vertical movements can change the horizon's curvature. Still, you can quickly remedy this by reversing the vertical movement.
- Use a two-finger swipe (also called pinch zoom) to zoom in and out. When you do this, the horizon's curvature might increase, but you can swipe vertically after obtaining the magnification you want to return to horizontal projection.
Sky dome projection
The sky dome projection compresses the whole sky within a circular area with the ground surrounding it. All celestial bodies that are visible in a given location and time are within this circular area. The center of the circular area corresponds to the zenith, the point on the sky directly above you, while its edge is the horizon.
To view Stellarium in sky dome projection:
- Use a two-finger swipe to zoom out the view to the least magnification (i.e., until you can no longer zoom out).
- From the top center, swipe your finger downward on the screen until the horizon is circular with the ground surrounding the sky. You can continue swiping downward after the horizon became circular, and you will get a distorted circle, but when you lift your finger, the shape of the horizon will "bounce" to circular.
While in sky dome projection, you can do the following:
- Swipe left or right along the vertical center to rotate the sky; use this to reorient the four cardinal directions to your mobile device's orientation.
- Use a two-finger swipe to zoom in to a particular celestial body or zoom out to see its vicinity.
View from above projection
The view from above projection is the opposite of the sky dome projection; the ground is in a small circular area surrounded by the sky. The ground kind of looks like a small planet. To see this view:
- Use a two-finger swipe to zoom out the view until you can no longer zoom out.
- From the bottom center, swipe your finger upward on the screen until the horizon is circular with the sky surrounding the ground.
Unlike in Stellarium for computers, the ground becomes semitransparent in the view from above projection, allowing you to see the celestial bodies that are under the horizon. I cannot find any configuration that can make the ground opaque (probably one of those features in Stellarium PLUS). Also, I cannot find any settings in Stellarium for computers that will make the ground semitransparent.
I just made-up the names of these projections, and you need not memorize them; you only need to understand the description I provided.
- There's no Stellarium Mobile Free in Ios but Stellarium PLUS cost ₱499.00. Stellarium Mobile Free is available in Android, but upgrading to Stellarium PLUS cost ₱1150.00. Not sure why they're priced differently.
- If you sufficiently zoom in some of the celestial bodies, you will see them how they look like instead of just dots in the sky. For example, if you zoom in the Moon or Mars, you will be able to see its surface. If you zoom in the Helix Nebula, you will see its eye-like structure.
- Stellarium works in both portrait and landscape. It's just that in landscape, the dialog boxes for Menu options and viewing options tend to cover more of the sky.
- Sometimes, the Search field and viewing options do not disappear after you tap outside them. I'm not sure if this is a bug or if there are other ways to close them. I simply close Stellarium when this happen because the last view is preserved when you reopen it.
Last updated on 02 Jan 2021.
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