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Lessons from the bush

We can learn a lot from Earth-focused nature observers.
OMearaStephen

I have great respect for Botswana’s safari veterans — especially the guides. Their visual awareness and keen knowledge of the bush wilderness is unrivaled. How often I have sat in amazement of their ability to pick out birds and animals in a rugged landscape — while driving a vehicle — usually long before I, or anyone else, notices them. I’m not talking about the broadside of an elephant, but about the white tip of a wild dog’s tail or the flick of a bushbuck’s ear barely visible above a wide expanse of tall grass. The guides are shining examples of how training leads to outstanding visual acuity that reaches far beyond the norm.

So this month, I thought I’d look at some basics of how these expert wilderness observers train, and apply them to visual telescopic observing, particularly of the planets. I’ll use Mars as my example because it’s still magnificent in the evening sky and has a relatively permanent large-scale landscape.

Lesson 1: Learn the landscape

Unlike a city with its moving traffic and construction, the bush landscape (barring catastrophe) changes little day to day. Because the natural environment is relatively static, when guides make repeat observations of it, they recall from their memories large-scale structures. This cache of images forms the foundation upon which discoveries are made.

Seasoned Mars observers approach their target the same way. They first familiarize themselves with the biggest bright features, such as the polar caps, and the extensive dark features, like Syrtis Major and Sinus Sabaeus. They thus build firm knowledge of the large-scale martian landscape, and that forms the foundation on which they can search for finer features or rogue phenomena, such as clouds and dust storms.

Impalas
Five animals are visible in this image — try locating them before reading further. Most identifiable at a glance are the three impala. The warthog, near center, can be easily mistaken for a log. The most difficult animal to see is the giraffe. Its spotted neck rises above the tall hedge of grass just right of center. Look at the 2 o’clock position beyond the impala at far right. Training your eyes to see earthly objects will help you become a better observer.
Stephen James O’Meara

Lesson 2: Make a quick scan

Both skilled terrestrial and telescopic observers begin their observations with a quick scan of the environment using their peripheral vision. As Marc Antrop and Veerle Van Eetvelde explain in their book Landscape Perspectives: The Holistic Nature of Landscape (Springer, 2017), a quick glance provides a wide-angle view in which the eye traces contours and fixes on objects that are conspicuous in the scene, noting the shape, size, and color of objects as the brain creates a mental image.

Once the general appearance of large-scale objects is stored in memory, any notable change in shape, size, or color can set off a mental alarm. For instance, an owl standing on a tree branch will distort the known contour of the branch (even when seen at a great distance), thereby making it conspicuous to the trained observer but “invisible” to a novice. Similarly, as seen through a telescope, a new dark marking on Mars — protruding, say, from Syrtis Major — will distort that feature’s familiar wedge-shaped pattern and grab the attention of a skilled observer, but perhaps not that of a novice.

Lesson 3: Perform a detailed inspection

When an alarm sounds in the mind, the eye/brain system shifts gear, changing from peripheral vision (sensitive to general shapes and movement) to direct vision (sensitive to fine detail and color). So if a safari veteran notices a foreign bulge on a tree with peripheral vision, the eye’s central vision can resolve it into an owl. This all occurs within a matter of seconds.

That the eye’s peripheral vision is sensitive to movement is another factor in picking out birds and animals in the bush. A wild dog whose body is hidden in the tall grass can give its location away to a perceptive observer with a swish of its tail. Once locked on to that tail, the observer’s central vision can perceive its white tip, thus identifying it as a distinctive marking of a wild dog.

In backyard astronomy, we generally use motion detection when searching for satellites. If a faint naked-eye satellite had no motion, we’d have no chance of detecting it at a glance. Motion also comes into play when we observe the planets. The primary cause is the vagaries of Earth’s turbulent atmosphere, which can shift details about and create false markings. But one trick of the amateur astronomer trade is to not track the planet with a clock drive.

As the planet drifts through the field of view, skilled observers use peripheral vision to wait out the times of bad seeing and catch glimpses of details under moments of steady seeing — before locking on to them with direct vision. The exchange between peripheral and direct vision can occur in a fraction of a second. By continually repeating this exercise, an observer can walk away from the telescope with a mental map of a planet’s appearance that may exceed expectations.

So give it a try. Both Mars and Saturn are well placed this month for learning their landscape, scanning their faces, and inspecting any fine details. As always, send your thoughts and comments to sjomeara31@gmail.com.

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