The Third Dimension

We take the third dimension for granted. On an average day, it does not matter that we take it for granted. In particular, I am thinking of “The Depth “part of what we perceive. For instance, most of the time, we are able to cross the road without getting hit, unless we are having a really bad day. We are able to put back things on the shelf without dropping them. We are able to shake hands without misjudging the distance, our friend’s palm is at. So yes, the third dimension exists, but we don’t bother with it really.

Fast forward to the end of the day. You step out of the house. You look up at the night sky. If you are fortunate, you have a clear sky. If you are extremely fortunate, there is a total power shutdown in your city. The night sky is dazzlingly beautiful with hundreds of stars of various colors and sizes. Now, the third-dimension matters like never before. To really perceive the night sky in its true splendor, we need to realize that the third-dimension changes everything that we think we see. Take, for instance, The Orion Constellation. Listed below are some top stars in the Orion Constellation.

Proper Name	Apparent Magnitude	Approx. Distance (Light years)	Radius (x R☉)	Luminosity (x L☉)	Mass (x M☉)
Betelgeuse	0.42	643.0	887.0	140,000.0	7.7
Rigel	0.18	860.0	78.9	66,000.0	18.0
Bellatrix	1.64	250.0	5.8	9,211.0	8.4
Mintaka	2.23	1,200.0	16.5	90,000.0	20.0
Alnilam	1.69	2,000.0	42.0	375,000.0	40.0
Alnitak	2.0	1,260.0	20.0	100,000.0	28.0
Saiph	2.07	650.0	22.2	56.9	15.5

Solar Radius is represented by R☉

Solar Luminosity is represented by L☉

Solar Mass is represented by M☉

Please note that the numbers given in the table above are largely indicative and have been given for the sake of easy layman’s comparison only. A lot of these technical details are not necessarily single numbers but a range of values and are better explained elsewhere by much more qualified people.

You would notice that all the seven prominent stars in the Orion Constellation are larger than the Sun. Betelgeuse is the largest of the seven, though the mass is relatively less. But the most interesting aspect of the constellation is, how far away each of the stars is from us. This third-dimension escapes us almost all the time. We all see Orion the Hunter, his belt, the shoulders, and feet. But what we do miss is that the seven stars are not in a single plane as is represented in most pictures.

I happened to come across a very nice mobile application that shows an Artificial Reality image of constellations. So, I could collect some photos of the Orion Constellation by rotating the facing image of the warrior. We can see the lateral view of the constellation which immediately gives us an idea of how far away the stars are from each other and from us.

You will have to stretch your imagination a little to “go behind” the two-dimensional image of the warrior. You will immediately see that Alnilam is so far away from them all. It sits more than 2000 light years away from the Sun. From this perspective, Alnilam, which has the highest absolute magnitude [varying between 275000 L☉ and 832000 L☉] finds its actual relative size.

The bright red is Betelgeuse, about 643 light years away. The bright blue star near the left shoulder is Bellatrix about 250 light years away. Rigel, the other bright blue star is 860 light years away located near the right knee in these images.

So, we see that the third dimension is a very important component in understanding the layout and vastness of the universe itself. 3D geometry plays a very significant role in astronomy. Add to that the relative and absolute motion of each and every object that we observe and study. Your head starts spinning in no time, in trying to understand the relative position of celestial objects, especially over a period of time.

The next time you look up at a star, do ask yourself, really how big is that star and how far is it?