Page 78 - BBC Sky at Night Beginners Guide to Astronomy - 2017 UK

OBSERVING

THE MOON

THE MOON: IT’S BIG, ROUND AND
BRIGHT. ANYONE CAN DISCOVER ITS
FINER DETAILS, WHETHER IT’S WITH THE
NAKED EYE OR BINOCULARS

Some astronomers seem to get change dramatically from one crescent, half, gibbous and full.
a complex about the Moon. It’s hour to the next. Another reason After full Moon the phases
not that they’re affected by it in it’s so good is that it’s easy to reverse as it starts waning;
werewolfi sh ways, but rather they fi nd. There’s no star-hopping or these are equally worth a look.
develop a loathing for our large, fi ddling with fi nderscopes, as the However, the post-full phases The low light
rocky satellite. Why? Well, these Moon quite plainly hangs about are generally seen very late in hits its mountains,
usually friendly astronomers just waiting for you to look at it. the night, when most people craters, valleys, crinkly
come to see it as a natural light prefer to sleep. ridges, rilles, escarpments
polluter, washing away all the MAGNIFY THE VIEW The zone between the light and all manner of other volcanic
faint, small and fuzzy galaxies The Moon is a stunning object and dark sections of the Moon is and impact features, casting
and nebulae they like to view. to look at, but there are times known as the ‘terminator’, and dramatic shadows across the
To them, the Moon is more of a when binoculars or a telescope this is the place to concentrate stark landscape. The view is
nuisance than an object that’s are the only things that’ll do it on for the most stunning lunar further enhanced by largely
worthy of observing. justice: for example, the fi rst few views. It’s along the waxing fl at, dark areas of solidifi ed lava
This is a real shame as the days after new Moon through to Moon’s terminator that, if you known as the lunar seas, over
Moon has so much to offer. just before full Moon. During this were standing on the lunar which shadows can stretch for
There’s simply no truth in the period, when the Moon is waxing, surface, the Sun would be rising. tens of kilometres. All of this
assertion that when ‘you’ve seen we see a sunlit, happy side and a
it once, you’ve seen it all’ – with contrasting unlit, spooky side.
binoculars and small telescopes The views of the bright side
the appearance of the Moon can give us the names of the phases:

EXPERIENCING ECLIPSES
Why do eclipses occur so infrequently? It
all has to do with the Moon’s tilted orbit

Over the course of a year the between the Sun and the Moon).
Sun moves across the sky on We don’t, however, as the Moon’s
a path known as the ecliptic. It orbit is tilted at an average of 5°
rises in the east and sets in the from the ecliptic.
west, in essence appearing like Most months this means that
it travels around Earth. from our point of view on Earth, During a total solar eclipse the Sun’s outer atmosphere is visible
If the Moon orbited Earth the Moon moves above or below
PETE LAWRENCE, THINKSTOCK month we would get an eclipse or below Earth’s shadow at full the Sun is 400 times bigger than Moon just covers the Sun
in this same plane, then each
the Sun at new Moon, and above
Due to a fantastic coincidence,
Moon. We only get an eclipse
of the Sun (when the Moon
during a total solar eclipse,
when the Moon’s orbit intersects
passes between the Sun and
the Moon, but around 400 times
allowing us to witness its
Earth) and an eclipse of the
the ecliptic and all three bodies
ghostly outer atmosphere,
further away. This means that they
Moon (when the Earth is
are in the correct alignment.
known as the corona.
appear to be the same size. The
78 skyatnightmagazine.com 2012