I don't usually write reviews in this blog, but in the case of the 'Universe2Go' product my interest was piqued and (in full disclosure), the company sent me a free device to take a look at with no promise of a review.

In a nutshell, it's a boxy viewer that holds your smartphone (a range of sizes can be accomodated) while a special planetarium app runs and 'projects' (more on that below) a starmap on top of the real night-sky. Therein lies the special trick of this product, it augments your view of the sky, and gives you an experience not unlike looking through a pair of binoculars - albeit a pair that talk, play music, and pop up all manner of information and guidance.

What showed up on my doorstep was an attractive, somewhat Apple-esque box with the viewer, some instructional material, and a cloth carry case. Some text was in German, not surprisingly since that's where this originates - but it's available to order online for the US and other countries and instructions come in multiple languages, including Spanish and French.

The box (Photo: C. Scharf)

At this point I had to throw it all in my suitcase because I was en route to Tokyo. Here's another shot post trans-Pacific trip, showing some of the internal optics.

A peek at the optics (Photo: C.Scharf)

The way the viewer works is quite clever. A smartphone fits into a space on the top of the box, held in with a flexible lid. The screen faces down, through a sheet of plastic. That image passes through an angled sheet of clear plastic and is projected onto a pair of circular mirrors (seen in the above photo). The reflected image from those mirrors then reflects back off the angled sheet and into your eyes.

The upshot is that you've suddenly got an augmented view of the world - or the sky. Whatever's on the smartphone screen (which displays a split screen - one for each eye) ends up overlaying your view through the device.

The viewer feels very solid, but not heavy, it's got a nice density to it and definitely seems of good quality.

Firing up the app (quickly downloaded, and activated with a special code in the box) gives you the option between a conventional starmap mode (no viewer needed) and the Planetarium mode - reminding you which direction to put your phone into the viewer.

Once you've wedged your smartphone in and closed the retaining lid you're good to go. But how do you control the software when you can't touch the phone? The solution is not a bad one, it's a simple menu scheme with a rolling set of options (not unlike a cylinder on a slot machine) and a floating cartoon hand that you tilt the box to move and activate a particular mode.

I found this took a bit of getting used to, with a certain amount of frustration, but that may have said more about my coordination skills than the interface which - given the isolation of the phone - is really a pretty elegant one. My first port of call was Starter, or Beginner, mode, that drops you straight into the skymap.

It's at this point that the neat trickery of the viewer's optics hits you. To do all of this through the phone's front facing camera (augmenting the screen image itself) would be a disaster because your eyes are a lot better at light capture in real time, while the camera can't take anything but grainy, messy images of a proper night sky. So the optics let you see the sky directly, while the reflection of the phone's screen really does overlay this in a nice, slightly spooky, way that doesn't blind you.

The response lag of the planetarium-style map is excellent, and although I had limited objects to spot in the Tokyo night sky (probably one of the brighter skies in the world!) it seemed to nail the positions well. A slightly disconcerting feature is that the faint-field stars (which are actually drawn from the 120,000 stars in the Hipparcos catalog) appear to switch off while you're moving fast, and then pop back when stationary. This might just be my eyes having a hard time tracking single pixels (on a Retina-resolution iPhone screen) or a software trick to enhance responsiveness.

Although I'm a professional astronomer by training, my sky-sense is pretty hopeless. I've been spoilt by operating big telecsopes where right ascension and declination coordinates go into a terminal and the machinery does the rest. So it was great to find myself getting immersed in looking around the sky and seeng where everything was.

In fact it was sufficiently absorbing that I hadn't realized that I'd left my phone's volume off before installing it. A quick prising out and fiddling got me the audio content. There's some ambient music and there's a ton of narration - hover on an object for a couple of seconds and the dialog starts up with history and astronomical information.

The other 'modes' cover Discoverer, Mythology, Deep-Sky, 3-D, Quiz, Search, and Expert. These offer varying degrees of detail and customization. Deep-Sky lets you 'zoom' in to nebulae, galaxies and other objects, with imagery to boot. Quiz was surprisingly entertaining - challenging you to go find stuff in the sky (a good way to learn), and Search was great - letting you pick an object and then follow the arrows to see it on the sky.

These were all fun, although again perhaps they'd have even more impact had I a truly dark sky to play with - but that was my fault. The Deep Sky mode let me 'discover' nebulae and galaxies, and I found that there was a bit of a game flow going on as I spun over to new objects and got the cross-hairs to light up, resulting in a zoom-in on the object and some text and audio descriptions. I suspect there are kids who would get into this aspect of the device, although I don't know how long it would hold their attention (on the other hand, as a parent I'd likely be grateful for even ten minutes of immersion in an activity like this). Either way, it was fun.

There are other bell and whistles here. If the International Space Station is overhead the App will tell you and guide you to it (really neat!) Planets are tracked, and the audio is a healthy 3-hours of material in total.

I'll definitely be taking this with me when I get the chance to look at a properly dark sky (not Tokyo, not New York!).

The bottom line

The good: doing augmented reality this way is great, doing a personal planetarium-come-star-map this way is inspired. The operation is mostly very smooth, and if you're a map-challenged, sometime stargazer, you'll love this gizmo. A definite option for the holiday season, especially for scientifically inclined youngsters.

The bad: Long-term use will likely hinge on how often you look at the night sky and need guidance. Hopefully software updates will continue to expand the capabilities. $99 seems a bit steep, even if the optics and build are high quality - on the other hand that includes free shipping worldwide.

Conclusion: Solid product that's well worth a look!