The moving universe, as we see it
In my humble opinion, science education, as it is presented on many TV documentaries, seems to rely on the assumption you have to have everything fast and flashy. It’s nothing new. TV news is often the same way, as are other programs.
It’s not only TV. This summer I had an opportunity to return to a major planetarium that I had not visited for more than 20 years. Sitting under the huge dome, as the lights went down I hoped for a relaxing presentation of the beauty of the night sky.
Instead, the program was presented with rapid, bright and very noisy special effects, taking the visitor on an imagined cosmic ride that would have given Dr. Albert Einstein whiplash. The lesson was about the current, prevailing theory of star formation and how generations of stars, through supernova explosions, spread heavier elements across space and add to the composition of developing worlds.
Although I enjoyed much of the show, my misgiving was in the impression that space, as we experience it, is fast and active. It certainly is, with particles of matter and energy flying at nearly the speed of light, and some dense stars whirling about at incredible rates.
The distances, however, are so vast that they are practically unfathomable on human terms. This perspective puts the human view of the universe at an incredibly still pace. It seems so still that the constellations you see tonight are nearly exactly the same that the builders of the Egyptian pyramids or the first Native Americans admired over their heads.
The night sky as we see it is subtle and quiet. Ideally, its only musical backdrop is a chorus of crickets or peep toads, the hooting of an owl or howling of a distant coyote. We do witness the march of the sky as it slowly revolves, as the Earth spins around.
If you use a backyard telescope and start locating distant star clusters or galaxies, you find them in their expected position in comparison to nearby foreground stars, as if they don’t move at all. They are even plotted on paper in star atlases and charts, which are good to use year after year. Yet, those star clusters and galaxies are moving at great speed. They are so distant you don’t notice it.
Astronomers are able to detect their relative speed and whether the object is moving away or toward the observer, through use of a spectroscope, which breaks up the light into its rainbow of colors.
Elements making up the stars in the cluster of galaxy—hydrogen or helium for example—absorb specific wavelengths of the light. The result is fine black lines at specific places in the spectrum of color. This information tells the astronomer both what elements are present, and the speed and motion of the object. Stars receding from us move toward the red light; approaching, toward the blue end of their spectrum.
This is done by noticing how the black lines slightly shift, either toward the red (longer wavelengths) or violet (shorter wavelengths) of the spectrum. This shift is called the “Doppler effect.” It is very much like the changing pitch of a car engine as it races past you, and the accompanying police siren that hopefully is not too far behind.
You can certainly get a lot out of TV documentaries and planetarium shows. Naturally, they only have so much time to present a lot of facts, and often the visual explanation is the best way to explain complex concepts. Many are worth watching or seeing. Balance the presentation, if you can, with even a few minutes outside under the night sky, or a view from a window with the room lights turned off. See how the incredibly distant stars sail by ever so slowly as the night goes by, and the constellations keep their familiar shape.
Whether you see for instance the Big Dipper low in the northwest, or the Northern Cross overhead on a late summer evening, they remain the friendly stars, looking the same year to year and just as your great grandparents enjoyed as well.
Last quarter moon is on Sept. 14.