Harrowsmith – June 2019

Harrowsmith Summer 2019 | 41

lion with a curved “sickle” of stars
for his head and mane of hair, and to
the left are three faint stars forming
his hindquarters. There is a dim
region of sky up and to the left of the
easternmost tail star (Denebola)
and at about the same distance as
the height of Leo’s head. Here, you
are looking directly out of our Milky
Way galaxy into intergalactic space.
There are few stars and not much
“smog” of gas and dust from our
galaxy to get in the way.
So, yes, there is not much to
see, but that is only because of the
vastness of space. To add drama to
this view, look about a fifth of this
distance back toward the Denebola.
Under a dark sky you will see a hazy
spatter of faint stars. This star
cluster nicely fills the field of view
of binoculars. It’s common as far
as star clusters go, but it appears
large because it’s relatively close to
us. In popular astronomy, we gauge
distance by the time it takes for light
to travel from there (the cluster)
to us: 280 light-years. There are
more than 40 stars in this cluster.
Imagine living on a planet around
one of those stars—the night would

have many bright stars to illuminate

your nightly walks.

There are three aspects of the

night sky: the moon, the stars and

the “texture” of the sky. The moon

progresses through its obvious

phases roughly each month. The

stars are not distributed evenly

across the celestial sphere. There

are bright ones in winter, faint

ones in spring, many faint ones

and a few bright ones in summer,

and again faint ones in autumn.

But the textures are more subtle.

The relatively faint stars of the

spring and autumn skies don’t

offer a dramatic contrast to the

background sky like the winter

stars do, so these two seasons have

a sky that does not appear as dark

or as black as winter.

The late summer sky is very

different. It has the most prominent

structures of our galaxy. There

are many stars, and many of

these are relatively near to us and

some are also quite bright. Going

fainter, or “deeper,” into the sky are

countless others—too far and too

faint to be seen individually but

whose combined light creates the

hazy band of the Milky Way. With

binoculars and telescopes, we can

pinpoint some of these stars, but

there will always be fainter and

more distant stars that perpetuate

the hazy structure.

Low in the summer sky is the

constellation Sagittarius, more

familiarly seen as the celestial

Teapot. Slightly to the right of the

spout is the centre of our galaxy. The

Milky Way seems to rise from its

spout like celestial steam. Halfway

across the celestial sphere, we

look out into space in the opposite

direction of the galaxy’s centre,

toward its outer rim, to the left of

the winter constellation Orion.

Under a dark sky, you can see the

faint and tenuous glow of that part

of the Milky Way.

Look over the accompanying star

map (see above) to to help get your

bearings. The four seasons have

their own features that help display

their different characters. Frequent

night walks will let you experience

the slow transition between them.

And that little bit of exercise will

help you see many cycles of the

celestial sphere. H

ENVIRONMENT: SUMMER SKY