After I posted my updated article titled “Wonders of the Night Sky with the Naked Eye” (see my last post dated 10 March 2011), I realized that I needed to post a corollary to it, bringing the attention of the readers to a truly wonderful tool of modern Information and Communication Technology that enables one to recreate the night sky anytime anywhere on the screen of a mobile smart phone. The application which makes this possible is the Google Sky Map and, for all practical purposes, it is a mobile and handy planetarium in two dimensions. It can be freely downloaded, installed and run on any handset hosting Google’s own Android Operating System, version 1.5 or later (the current version available is 2.3 and version 3.0 is round the corner). The handset also needs to have a built in magnetometer which gives it a compass functionality and a GPS (Global Positioning System) receiver with which accurate location and time information can be obtained automatically from a set of four or more earth-orbiting GPS satellites. Such devices nowadays also provide 3G internet connectivity, but this is not necessary for this particular application.
When the Sky Map application is turned on, the screen is filled with a night sky view of the celestial objects – stars, planets, constellations, etc. – corresponding to the part of the sky at which the device is pointing flat-on. If this is done at night, it gives the dramatic illusion that the built-in camera is capturing the sky and displaying the image on the screen. Actually, the camera has no role whatever to play and the image we see is assembled from a database of information on over a thousand stars, planets, constellations, Messier objects, etc. The magnetometer and the GPS receiver define the area of the accessible sky at the corresponding location and time. As the device is turned or moved around, the screen view changes in consonance and we end up looking at the part of the sky always facing the device. We realize that the camera has no role to play when we turn the application on in broad daylight or hold the device against any obstacle, small or big, even the earth itself under our feet, anywhere anytime, and still see the ‘night sky’ on the screen. In other words, we can as easily see the night sky on the other side of the earth beneath our feet as we can see through a wall in front of us or the ceiling overhead in an enclosed room. We get the grand illusion that the night sky view is totally transparent to anything and everything around us.
The following picture shows three different android smart phone screens displaying the sky map in different contexts and locations:
Visible Layers & Controls
The Google Sky Map organizes the celestial objects into layers; each layer can be toggled on or off using on-screen touch controls. The layers are: (i) Stars, (ii) Constellations, (iii) Messier objects, (iv) Planets, (v) Right Ascension & Declination grid, and (vi) Horizon and cardinal points. The brightest stars and prominent constellations are labeled, as also the planets which are displayed larger than actual size. At the bottom of the screen are zoom controls and a toggle to switch between automatic and manual mode. In the manual mode, one can drag the map with the finger to explore any part of the sky. On multi-touch screens like the one I have in my expensive Dell Streak 5, one can also rotate the map with two fingers and use a pinch gesture to zoom in and out.
Search & Find
One of the most powerful uses of the sky map is to search for any celestial object and locate it on the map. If an object, say a planet or star or constellation or Messier object, is selected for the search function, the screen will display a targeting circle with an arrow showing the direction in which to move the device in search of the object (see picture below). As the device closes in on the target, the circle will change from blue to red, finally turning orange when the target is within the field of view. It is then very easy to locate and even to see it if it happens to be in the visible part of the night sky at that moment. Objects normally invisible in the glare of the Sun can be located even if they are in the immediate neighborhood of the Sun. Amateur astronomers will find it very useful to locate an elusive object like planet Mercury or a sun-grazing comet (if the database is updated to include it).
When looking at the night sky through cloudy skies, often one finds it extremely difficult to identify a lone bright star showing through clouds enveloping most of the night sky. This is because one can’t readily identify the constellation it belongs to. The Sky Map provides a fool proof solution to such a problem. By zeroing in on the object it can be easily identified in relation to its constellation and neighboring bright objects in the sky map. I have found this to be one of the most useful features of the application.
Time Travel mode enables one to recreate the sky at times other than the present. After selecting ‘Time Travel’ from the main menu, one can set any location, and any date (between 1900 and 2100) and time for that location and press ‘Go’ to get into the new mode. One can then conveniently move forwards or backwards in time at different speeds from there. In this mode one can simulate a variety of situations and find answers to numerous questions which would remain only hypothetical otherwise. For example, I have been able to recreate and follow, to a fair degree of accuracy, the occurrence of the Total Solar Eclipse on 16 Feb 1980 from the Tungabhadra dam site in Karnataka (see my blog post titled “The Great Total Solar Eclipse of 16 February 1980”).
Sky Map contains a selection of thumbnail photographs from Google Sky’s Hubble Gallery of superb pictures taken by the Hubble Space Telescope. Inside it, one can select any particular object and blow it up to a full size image. By switching over to the Search mode, the object can be located on the Sky Map.
Night Vision Mode
This mode is designed to protect one’s dark-adapted eyes during prolonged observations on a dark night, well away from any disturbing lights, as is necessary for any serious exploration of the wonders of the night sky (see my previous blog post). In this mode, the screen will be dimmed and the map appears in a red color, with no bright displays on or off the screen.
It is barely a decade since one had to rely solely on the print medium to provide the night sky maps to help explore the wonders of the night sky as set out in my last blog post. With the advent of the android smart phone the scenario has changed dramatically. Thanks to Google, all those weekly, monthly and seasonal star charts have become irrelevant for anyone who can afford a modestly priced smart phone with the necessary hardware features and the free Google Sky Map application. In the short period since this application has become available on the android platform, over a quarter of a million people have downloaded it into their devices. This augurs well for a major resurgence of worldwide interest in the observation of the night sky as a hobby.
The Dell Streak 5” mobile mini tablet PC I purchased recently is certainly not modestly priced by any standards. For the price I paid I could have easily got a sophisticated desktop or laptop computer, but its great advantage lies in its mobility, portability, durability and ease of use, apart from the state-of-the-art hardware and software features. Everything is available at the tip, and the tap, of a finger. It fits snugly into a shirt pocket and doubles up as a slightly oversized and overweight, but not inconvenient, 3G mobile phone.
Despite its versatility, the Sky Map application has some major shortcomings which can be overcome in the field only with the additional support of a laptop or netbook computer with a resident sophisticated observational astronomy software package like Starry Night Pro. Nevertheless, in these last few weeks I have discovered a whole new meaning and purpose for my longstanding hobby of Observational Astronomy. I only wish the invention had come earlier, at least coincidentally with the revival of interest in my other major hobby of (Digital) Photography.