Astronomerica: 3D Stereoscopic Constellations

The following are stereoscopic pairs that, when your eyes are focused properly and they can fuse the left and right images together, you can see the varying distances of the main stars in the constellation figures at varying depths. I created these using Cartes du Ciel for the placement of the stars, Sky Safari Pro for the magnitudes and distances, and Paint.net for creating the images.

I've always been fascinated by the alignment of stars at various distances that seem to form two dimensional figures on a sky dome, and trying to visualize them as they are in actual three dimensional space. I have calculated the most distant star in each constellation and used the percentages of that distance for the other stars. They are in the correct depth order and I have tried to make the percentages as close to actual as possible, but there are limitations to this technique, so they are not perfect. But the point is to be able to start seeing the sky not as a 2D dome, but as it really is- a huge window into 3D space. I hope these help.

How to view a stereoscopic image pair

These image pairs allow for the use of either the "parallel view" technique, in which your left eye is looking at the left image, and your right eye at the right image, or the "cross view" technique, where your eyes are cross-eyed and looking at the opposite side images.

Most people see better using one or the other technique. I can see both, but I prefer parallel view.

In parallel view, your focus is deeper than the screen. This is the technique used for "Magic Eye" hidden pictures. Some people can see these fairly easily, and others never seem to be able to crack the code. The best explanation I have is to set the images so they are level, then look at the wall across the room. Bring your vision down to the screen and continue to relax your vision to the point where it is fuzzy and defocused. At some point, you will realize the two images have become three or even four images. You want to focus on the middle of three images until you can see it clearly without any double image. It should suddenly snap into focus and you'll say "Aha!"

In cross view, the image seems to pop out or hover above the screen. Again, some can see this version better, others can't. In this case, hold your finger in front of your nose and gradually move it toward the screen. At some point you will achieve fusion of the two sides and the 3D image will snap into focus. "Aha!"

How do you know which technique works better for you? Take a look at the image pair below. If the P looks closer, you are using parallel view, if the C is closer, you are using cross view.

Side-by-side stereogram to determine parallel or cross view preference.

Start with the small image pairs as they appear on the page. You can click on an image for a larger size if you are viewing on a phone or small screen. In parallel view, if the image is too large, your eyes can no longer fuse the images into one. If that's happening, get further from the screen or use the smaller image. The correct image scale for your screen is critical, since these images have a very wide depth range. If it's still too large, try zooming out your screen (on a Windows machine, press CTRL and scroll the mouse wheel down to zoom out).

Practice on this simple image pair of Sirius. Once you see a middle image of the star, focus on it. If you are using parallel view, the label will appear slightly further away than the star, and if you are using cross view, the label will appear closer than the star. In the actual constellation images, the label will always be at the same focal distance as the star. This gives you the basic concept.

It is important to determine which view comes more naturally to you. If you use the wrong technique (i.e., cross view on the parallel view image pairs), depths will be reversed from what they should be- closer stars will appear further away and vice versa. Check the data at the bottom of each constellation post to make sure you're viewing the correct image pairs with the matching technique.