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Archive for the 'astronomy' Category

Maps Of The Moon And Mars For Android

Application Name: Moon Maps

Description: Photo maps of the moon from Lunar Orbiter and Clementine.

Publisher’s website: Moon Map

Cost: Free (ad-supported)

Version/date reviewed: v.1.1.1  /  8-14-11

Phone/OS: Droid X / Android 2.3


Android Market (mobile app only)
Android Market (browser)

Application Name: Mars Map

Description: Mars map from the Mars Global Digital Image Mosaic.

Publisher’s website: Atlogis Map Shop

Cost: Free (ad-supported)

Version/date reviewed: v.1.0.7  /  8-14-11

Phone/OS: Droid X / Android 2.3


Android Market (mobile app only)
Android Market (browser)

Something a bit different – geography but not of the Earth, celestial geography of the Moon and Mars. Both apps are similar in appearance and function, not surprising since they’re both from the same company.


Moon Maps starts off with a whole-moon display; locations of major features and Apollo landing sites are plotted in colored text. As you zoom in, more features are labeled …


Until you get the highest possible zoom level …


The horizontal “stripes” are an artifact of the imaging process. These are images from the Lunar Orbiter probes, shot in the 60s on roll film (pre-solid-state imaging), which was processed on the satellite in lunar orbit, scanned in strips, transmitted to Earth, then pieced together to form a continuous image.


Moon Maps offers an alternative image source from the more-recent Clementine probe, but while the “stripes” are gone, the imagery tends to be darker and of poorer resolution than that from the Lunar Orbiter.


The app comes with a searchable database of lunar features and Apollo landing sites; select a feature, and it will zoom to the correct location.


The Mars Map app operates in a similar fashion, though it uses only one image set, the Mars Global Digital Image Mosaic, generated from Viking Orbiter imagery from the 1970s, carefully selected and heavily processed to make it as uniform in lighting as possible across the surface.


Viking imagery isn’t quite as high in resolution as that from more recent Mars probes, but there’s still lots of interesting features visible …


… like this great shot of the crater at the top of Olympus Mons (aka Olympus Rupes), one of the largest volcanoes in the solar system, shown here at highest map resolution. As with Moon Maps, there’s also a searchable database to help you locate specific objects, and the locations of probes that landed successfully on Mars (e.g. Viking, Pathfinder, Mars, Spirit and Opportunity).

Other thoughts: Can’t complain too much, since the apps are free, but the ads do take up a fair amount of screen space.

Final thoughts: Great apps for astronomy fans and map nerds alike. I hope the imagery gets updated in the near future with higher-resolution data.

Day/Night World Map

Application Name: Daylight World Map

Description: Shows day/night regions in world map.

Publisher’s website: SPWebGames

Cost: Free (ad-supported

Version/date reviewed: v.2.31  /  6-15-11

Phone/OS: Droid X / Android 2.2

Android Market (mobile app only)
Android Market (browser)

Daylight World Map is the Android version of the classic Geochron wall clock that shows day/night conditions on a scrolling world map, but without the multi-thousand-dollar price tag.


Shaded areas indicate night (sun below horizon, while light areas indicate daylight; the yellow dot is the current location where the sun is directly overhead. Red dots are cities (which can be turned on/off), and the crosshairs show the current selected location.

The control icons on the left/right are a bit cryptic. On the left, top to bottom, they are:

  • Full-screen – Shows the map view full screen, without control icons or the ad.
  • Zoom in
  • Zoom out
  • Info – Toggles an info box for the currently selected location:


  • Settings – Lets you select the map background, turn cities on/off, and turn the info box on/off:


  • Exit – Exits the program.

The right controls:

  • Set location – Select this, and then choose either your phone location (at the top of the list), or the desired country:


  • After selecting a country, you’re given an additional control to select the city:


  • Date control – Lets you change the date for which the sunlight map is displayed (from the default, which is the current date).
  • Time control – Lets you change the time for the sunlight map (default is now). It’s in UTC (Greenwich time), so you’ll need to know the offset in hours between your current time zone and Greenwich time.
  • Time controls – The right/left arrow controls let you speed up/slow down/reverse time, and watch an animated view how the daylight zone changes. Tap on either of these buttons, and a “stop” button shows up below them to stop the animation. Tap on the “stop” button, and it changes to an “RT” button, “real-time”, that brings the display back to the current day and time.


As a bonus, it installs an Android widget that displays a mini-map on any Android screen that has enough free space. Long-tap on the widget, and it starts up the full app.

Other issues: Crashed once on me, but otherwise worked fine.

Final thoughts: A nice implementation of a day/night world map. I wish the icons were a bit more intuitive, and easier to view onscreen. But once you learn how they work, it’s not too tough to remember what functions they represent.

Will There Be Starry Skies In Your Area?

Application Name: Clear Sky Droid

Description: Shows sky clarity and astronomical viewing conditions for nearby areas.

Publisher’s website: Zero Credibility

Cost: Free; $0.99 donation version.

Version/date reviewed: v.1.1.6  /  11-4-10

Phone/OS: Droid X / Android 2.2


Android Market link (mobile app only)
Android Market link (browser)

If you’re an astronomer interested in whether telescope viewing conditions will be good, a photographer interested in upcoming light conditions, or you just want to know if the skies will be clear for good stargazing, Clear Sky Droid offers an easy way to get this info. The app is a front-end interface to the ClearDarkSky website, where it retrieves the data it displays.


Figure 1: When you first start up the app, it gets your location from GPS or network data, and shows you a list of monitored locations in your general area, listed by distance from you. You can also search for a specific location, or consult a list of saved favorite locations. Tap on any of the items in the list, and you’ll get the option of adding it to your favorites, showing it on a map, or getting fuller details …


Figure 2: This is a forecast for the next day or two of what conditions will be like for astronomical viewing. A more detailed description is available here, but basically the top grouping describes the critical factors for good sky conditions, and the darker the square the better the conditions are expected to be.

  • Cloud Cover: How much of the sky is obscured by clouds.
  • Transparency: How clear the sky is; usually reflects the humidity.
  • Seeing: How stable is the atmosphere. Most important if you want to view using a telescope. In poor seeing conditions, the stars will be twinkling a lot as seen by naked eye, but you can still get some decent stargazing in. However, in a telescope, the sky will be jumping around so much that you’ll barely be able to make out any details in faint objects, or fine detail in bright objects like the Moon and planets.
  • Darkness: Usually bad when the sun is up :), but also affected by the moon’s phase and location, and scattering in the atmosphere.

Other Issues: None – no problems.

Final thoughts: Indispensable for the serious amateur astronomer, or the recreational skygazer. For the rest, probably won’t see regular use, but might come in handy on the occasional outdoor trip.

Living in the sun (formerly ZP Compass): Local Sun/Moon Info For Android

Application Name: Living in the sun – Sundial Moondial

Description: Compass with indicators that show direction/altitude of sun/moon; moon phase calendar; twilight time tables.

Publisher’s website: AppZeroPoint

Cost: Free version (ad-supported); $3 Pro version removes ads, adds additional features

Version/date reviewed: v.1.5.4  /  10-31-10

Phone/OS: Droid X / Android 2.2

Android Market link (mobile app only)
Android Market link (browser)

The Living in the sun app offers a standard compass with direction, but also additional astronomical information for your current location.


Figure 1: Probably the most interesting view in Living in the sun is the actual compass view. The number at top shows your current bearing direction (which way your phone is pointed). The red arrow always points in the direction of north. The gold arrow shows you the direction of the sun, with the sun’s image showing approximately the altitude; you also have numerical direction/altitude data for the sun at the bottom. The gray arrow shows the moon’s direction; the missing moon image indicates that it’s below the horizon at this time. The numerical moon data at the bottom reflects this with the negative value for altitude. You can turn any of these indicators on/off in the Settings section; in this image, I have the magnetic north arrow turned off.


Figure 2: A calendrical display shows the phases of the moon. Tapping on any of the dates, or selecting the “Twilight” display option …


Figure 3: … brings up a table with times for sunrise/sunset, moonrise/moonset, and various kinds of twilight times (usually defined by a certain distance of the sun below the horizon).

In addition to removing the adds, the paid version offers a few extra features:

  • A map of twilight area
  • A map of the sun and moon across the sky at various times during the day

Issues: Program worked fine – no crashes. I do wish it gave you the option of selecting any location; it only gives data for your current location. The GPS is on continuously in compass mode, which can drain your battery if you forget to turn it off.

Final thoughts: There are better compass apps around, but if you need the astronomical data (sun/moon/twilight), this free app offers a nice combination of features.

Android Live Wallpaper Of The Earth

Application Name: Earth Live Wallpaper

Description: Animated live wallpaper of Earth and other astronomical bodies, real and imagined.

Publisher’s website: Earth Live Wallpaper

Cost: Free version 1 (donationware); newer version 2 offers faster performance for about $2.75.

Version/date reviewed: v.1.3.9  /  10-31-10

Phone/OS: Droid X / Android 2.2


Android Market link (mobile app only) – main app
Android Market link (browser)


Android Market link (mobile app only) – map data
Android Market link (browser)

Note: You should download the app first, then the data. Some Android phones may not support live wallpaper.

Earth Live Wallpaper lets you show an animated image of the Earth as a background in your Android home screens. It also offers options to display other solar system objects like the sun, planets, moons, etc., as well as fictional/imaginary astronomical objects (e.g. planets from the Star Wars universe, Star Trek, Futurama, Avatar, etc.). You also have a huge number of options you can set:

  • Show the moon rotating around the Earth
  • Choose from a variety of background images, and how they’re animated
  • Add an animated starfield
  • Have the globe spin on its axis, rotate freely; interact with you as you swipe
  • And more …

Access the app from the Settings => Wallpaper => Live Wallpaper list, where it’s shown as EarthRot. For real geography, your map choices are:

Realtime Earth + Clouds => Shows the Earth with actual cloud patterns (updated every 3 hours), and day/night shading with city lights
Static Earth => Globe image fully lit with an arbitrary cloud pattern
Earth => Fully lit globe with no clouds
Earth city lights => Globe at night, with artificial lights from human activity.

I prefer the realtime earth, since it shows up-to-date data like the cloud patterns and night/day terminator line. But it will use about 70 kB of data every time it refreshes the cloud data, which changes every 3 hours or so; that’s close to 17 MB of data in a month, which might be an issue if you’re on a limited data plan.

Issues: None. My phone supports live wallpaper; if yours doesn’t, this wallpaper won’t be terribly useful. Live wallpapers also consume a little bit of extra battery power, so if battery life is a critical issue, you might want to think twice.

Final thoughts: Looks cool, and the realtime Earth view offers useful information. Not an essential app, but if you can live with the slight power drain, worth having.

Tricorder: Android Homage To Star Trek

Application Name: Tricorder

Description: Multiple sensor data output, including GPS and compass; solar data.

Publisher’s website: moonblink

Cost: Free

Version/date reviewed: v.5.11  /  10-5-10

Phone/OS: Droid X / Android 2.2

Android Market link (mobile app only)
Android Market link (browser)

While comparing his Droid Incredible with my Droid X a few months ago, a friend commented that the sensor capabilities of the Droids reminded him of the tricorder from the original Star Trek series, a multi-purpose data collector and analyzer. What he didn’t know was that I had a copy of the Android Tricorder app on my unit that makes the connection even more explicit. I can’t say that I find it totally useful – I think there are better apps for many of the functions. But it’s fun to use to show off your Android’s capabilities, and it does have one feature related to GPS accuracy that might surprise you.


Figure 1: A “gravity meter” monitors input from the orientation and accelerometer sensors.


Figure 2: The magnetometer displays information from the unit’s magnetic sensor.


Figure 3: An acoustic meter displays the waveform, spectrum, and noise level for input into the unit’s main microphone (here, me whistling a note).


Figure 4: The geographic section displays location from both network data and GPS satellites; the former is a nice touch, since that data is either not presented by other GPS apps, or is superseded by the GPS data when a fix is acquired. The display at the bottom shows the satellite sky map, and a compass with both true (T) and magnetic (N) directions. Wouldn’t want to use it for navigation, though.


Figure 5: Electromagnetic sensor shows the strength of the local WiFi networks, as well as that of the cellular network. There are lots of apps for the former, but I haven’t seen that many that show cellular network strength this clearly – a good alternative to the cell signal bars on your status bar.


Figure 6: You might think that a solar activity sensor, showing downloaded solar data, might be interesting but not particularly useful. But the plots of proton/electron flux at the bottom can reflect on how accurate your GPS position measurement is. As the sun moves into a more active phase, these fluxes can affect conditions in the Earth’s ionosphere, which in turn can make GPS less accurate. So if you see those plots rising near the end, that would suggest that your GPS position might be less reliably accurate.

Other Issues:

None ; worked fine every time.

Final thoughts:

Perhaps not the best sensor app out there, but too cool in appearance and function not to have, and the solar data is hard to find elsewhere.