62 ASTRONOMY • APRIL 2020SECRET SKY
A sunset by the
sea has a magic all
its own. As “the
golden apple of the Sun”
nears the horizon, it shim-
mers like a beauty whose
tresses unfurl like a glittery
path from horizon to shore.
Science fiction author Ray
Bradbury borrowed “the
golden apples of the Sun”
— the last line of William
Butler Yeats’ 1899 poem
“The Song of Wandering
Aengus” — to use as the
title of his 1953 anthology of
short stories and as a meta-
phor for taking a cupful of
fire from the Sun.
On February 26, 2019,
Edmund K. Parowski of
Williams, Arizona, photo-
graphed a stunning sunset
from the volcanic island of
Santorini (Figure 1). This
view from Fira on the east-
ern wall of the collapsed caldera overlooks Nea Kameni
(Greek for “new volcano,” in reference to the caldera’s
still-emerging central island) and the Aegean Sea
beyond. The image captures the feel of the sunsets that
have inspired poets for ages. But there is more to the
image than meets the eye.
Particularly, note the two Suns. As Parowski wrote,
“I haven’t seen anything quite like this before. It seems
as if both Sun images are casting separate ref lections
on the water.” Parowski’s is indeed a fascinating shot,
worthy of the cover of Isaac Asimov’s short story
“Nightfall,” where a world is constantly illuminated by
multiple suns. But one has only to look carefully at the
image to reveal the secret behind the magic of this
sunset.
At a glance, it looks as if a strong mirage has created
a distorted second Sun to appear well below the true
Sun. The second Sun lies just below a band of haze
whose bottom edge appears to lie about one solar diam-
eter above the dark water horizon, skirting the second
Sun’s upper limb. But this is an illusion whose solution
lies in the position of the true horizon.Where water meets sky
The apparent horizon is not the true horizon. It only
marks the position of a change in the intensity of the
water’s rippled surface. The bottom edge of the band of
haze marks the position of the true horizon. Between it
and the top edge of the dark water lies a bright band of
calm water, in which we see the ref lection of the Sun.
This becomes clear in Figure 2, which Parowski cap-
tured when the Sun neared the true horizon.
There’s yet another illusion. As Parowski noted, in
Figure 1, it appears that the two Suns are creating sepa-
rate glitter paths. But they’re
not. What we see i s a compou nd
single glitter path. Far out at
sea, the water appears relatively
calm, which would allow for a
near, still-water ref lection of
the true Sun. The glitter path
broadens in the region of dark
water, because the water’s sur-
face is more disturbed with
steeper wave fronts. Nea
Kameni and its shadow then interrupt the glitter path,
which continues to broaden as the rippling water closer
to the viewer becomes more agitated, causing the light
to spread out over a greater area. Parowski’s image is
yet another reminder of edifying words by Yeats: “The
world is full of magic things, patiently waiting for our
senses to grow sharper.”
A s a lway s , be su re to send you r t hou g ht s a nd obser-
vations of any curious phenomena to sjomeara31@
gmail.com.How many Suns do you see?
Reflections on
a sunset
FIGURE 1. Two Suns
feature in this
beautiful but
seemingly weird
sunset. ALL IMAGES:
EDMUND K. PAROWSKIThe
apparent
horizon is
not the true
horizon.BY STEPHEN
JAMES O’MEARA
Stephen is a globe-
trotting observer who
is always looking
for the next great
celestial event.BROWSE THE “SECRET SKY” ARCHIVE AT
http://www.Astronomy.com/OMearaFIGURE 2. Left: The true Sun (near top) reflects in calm water
(below), with a fatter glitter path in agitated dark water.
Right: The true Sun nears the horizon, just prior to setting. Note
the bright region of calm water between the dense horizon haze
(in which the true Sun lies) and the dark water below, creating
a false horizon.