In the still of the night, on a ridge top beside a quiet country road, an old oak tree enjoys a long view of valleys and sky. What changes it must have seen as the years turned and the seasons slipped by, day by day and night by night.
Most of us will see the sun cross the sky throughout nearly every
day. We know that the stars will also cross at night, but not many of us note
their passage through the dark from dusk to dawn. How many nights has the old
oak watched as the stars made their slow traverse across the sky? It has seen
all the patterns made as the sun, moon, planets and stars rise and set.
Do the stars rise in the east and set in the west as the sun and
moon do? The short answer is not exactly, almost oddly enough. As Earth
revolves, most of the stars rise and set, but the stars to the north and south
arc around the northern and southern axes of our rotation. If we looked out
into space perpendicularly to our axis of rotation, the stars we would see
would rise in the east and set in the west. The further north or south one
looks, the tighter is the arc of the stars.
Where we are in the northern hemisphere, we have a view of the
northern polar axis, which conveniently sits on a bright star we’ve named
Polaris, the North Star. The stars nearest Polaris will travel in a tight
circle around it as Earth rotates, never rising or setting at a horizon. The
farther out from Polaris the stars are, the wider their circles. Far enough from
Polaris the stars’ larger paths take them from one horizon to the other; these
stars rise and set. If we were on the equator, the stars due east would rise
vertically, and set due west. From our latitude as one’s gaze moves south the
apparent motion of the stars follows an arc above the southern horizon; the
center of that arc is the southern axis, which we can’t see because it is above
the south pole beyond the horizon.
The photograph of the oak tree I’m sharing here covers a lot of
sky in its wide field of view. The stars near the bottom of the image are in
the south, arcing across the sky as they travel around the southern axis below
the horizon. The stars at the top of the photograph are traveling in a wide
circle around the northern axis, which is out of view above and to the left.
The area between the southern arcs and the northern arcs is the celestial
equator. Because we are north of Earth’s equator, the celestial equator is in
the southern half of the sky; were we on the equator, it would extend from east
to west directly overhead.
To keep abreast of David Wilson’s most current photography or purchase
a print, visit and contact him at his website mindscapefx.com or follow him on Instagram at @david_wilson_mfx.
This article appears in The Battle for Elk River.
