IMAX movies differ from ordinary narrative films in a number of ways. You don't see ads for them on television or in newspapers. You often enter knowing very little about what you're going to see. You typically attend them with your entire family or up to hundreds of classmates. And you probably don't ever think to buy the power-diminishing home video, unless maybe you're an educator covering similar material.

Nonetheless, large format movies continue to be made, some of them on the fringes. Two such works make their home video debuts next Tuesday in a single Blu-ray/Blu-ray 3D disc billed a Galactic Adventures Double Feature. Though their titles sound downright definitive, you'd be hard-pressed to find documentaries as obscure as these two. First released July 2007 and definitely available On Demand at least four years ago, 3D Sun has yet to accumulate five votes on the Internet Movie Database. Not even those determined to count as one of the site's regular voters or click-crazy accidents have added up to five in the six and a half years since the film's debut. That's still better off than Mars 3D, a film that isn't even listed on IMDb. The official filmography of Barry Kimm, a director of both, states that Mars 3D is a 2005 release that screened in Chicago's Adler Planetarium and Tokyo's MeSci. I'm 95% certain I saw it sometime around 2007 at the Science Museum of Minnesota's Omnitheater, where it apparently premiered in the fall of 2004.

It's worth noting that though they are distributed by Image Entertainment, a branch of RLJ Entertainment that frequently distributes IMAX docs, the word IMAX is nowhere to be found. While 3D Sun is apparently an IMAX 3D film (though not designated as such here), Mars 3D is not. The two films together add up to a single IMAX documentary's standard runtime of 43 minutes. Each details efforts made by NASA to three-dimensionally photograph one of the most important bodies in our solar system.

Al Roker narrates 3D Sun, which explains exactly how in 2006 NASA launched the STEREO twins, two nearly identical solar-powered spacecraft, to opposite sides of the Earth to create 3D imagery of the Sun. The project, spearheaded by Madhulika Guhathakurta who compares the mission to Lewis and Clark's famed expedition, gives us a better understanding of solar storms. The observations have enabled scientists on Earth to improve their forecasts (hence, the selection of Roker?) of solar storms unfolding on 11-year cycles.

Solar blasts, we're told, once caused a city-wide Quebec blackout and in other instances have caused flights to be rerouted and GPS signals to be disturbed for ten minutes. Yes, though Roker and an assortment of talking heads try hard, the subject matter doesn't seem all that interesting or important. Furthermore, most of the actual 3D images are saved for the film's end, having us rely on detailed computer-animated renderings until then. That design is kind of anticlimactic, too, since the color-tinted images resemble an old movie studio logo and do not convey much to us.

3D Sun feels slight, running barely twenty minutes plus end credits. Mars 3D is even slighter, needing credits to just barely cross the 20-minute mark. This short documents NASA's launch of Spirit and Opportunities, two rovers sent to land on Mars and gain insight into Earth's closest neighbor. The mission aims to answer "Has there ever been or could there ever be life on Mars?" You'd be better off listening to David Bowie's "Life on Mars" five times or watching half an episode of either the UK or US TV dramas of the same name. Truthfully, the possibility of extraterrestrial life has never seemed as dull as here.

There's a little bit of human interest as the project's principal investigator Steve Squyres nervously watches one of the Cape Canaveral launches with his family and he and others await updates on whether the rover, padded by a bunch of balls in a bounce-landing, has survived the trip to the red planet. But there are no striking visuals to go with this content. We again rely on computer-animated representations and the graphics already seem hopelessly dated in 2013. The film moves to 3D halfway in, but it's not the kind of 3D that flourishes today (nor is it as spectacular as the case promises), as we're finally shown actual pictures of Mars' rocky desert that could have just as easily been the work of a John Carter extra in Utah. It's a little underwhelming and you're surprised to see it end as soon as it does. (At least you're not paying museum theater prices!) While sporting nicer photography, Disney's kindred 40-minute 2006 IMAX feature Roving Mars isn't really any better or more interesting.

VIDEO and AUDIO

Both films appear in 1.78:1 widescreen, utilizing the Blu-ray format's every pixel and filling now-prevalent 16:9 screens. 3D Sun looks pretty terrific, its space animations holding appeal even in this post-WALL•E age. The visuals are sharp and clean, although some footage of Earth scientists is clearly not shot with top of the line equipment. Mars 3D is less impressive. Not only is it not IMAX, it doesn't even look like HD as we know it these days. The transfer is without specific problems, but it's more limited and much less potent than you expect for this kind of disc.

The 5.1 DTS-HD master audio soundtracks are both satisfactory, presenting music and dialogue with clarity, weight, and impact. Neither movie gets any subtitles, but 3D Sun does include a Spanish language track.

BONUS FEATURES, MENUS, PACKAGING and DESIGN

The disc's only bonus are theatrical trailers for the following nine IMAX 3D movies: Space Junk, Sun 3D, The Ultimate Wave Tahiti, Mummies: Secret of the Pharaohs, Dinosaurs Alive 3D, Dinosaurs: Giants of Patagonia, Legends of Flight, Wild Ocean, and Rescue 3D. The trailers, presented in full 1080p and DTS 5.1, are kindly accessible individually and collectively with a "Play All." You'll notice that Mars 3D doesn't even have a trailer and that Sun 3D's feels more like a booking promo for exhibitors.

Each movie gets its own tasteful scored menu displaying clips in a wide frame.

The side-snapped keepcase uses its translucency to display cover art of IMAX documentaries available on Blu-ray from Image Entertainment.

CLOSING THOUGHTS

I think anyone who sees the cover of this Galactic Adventures Double Feature is going to assume these are IMAX films, but only one of them actually is. That explains why Mars 3D doesn't quite pack the audio-visual punch of large-format documentaries. And yet, neither it nor 3D Sun delivers the modest substance of those 40-minute spectacle-driven films. Furthermore, science-loving tech geeks don't even find the eye-catching 3D visuals they may expect to get from this platter.

Though you probably won't hate either doc, you also won't likely be able to appreciate them as more than NASA PR pieces explaining and justifying these two costly projects in terms the general public can easily understand. Plus, these films and the missions they document are now old enough that you either already know what they're saying or simply don't care. While it's nice for these films to be preserved in high definition, it's tough to see how they're worth your time and money as is and not bundled with a number of other like-minded space documentaries.

Buy Galactic Adventures Double Feature Blu-ray 3D/2D at Amazon.com