hpr-knowledge-base/hpr_transcripts/hpr1392.txt

Episode: 1392
Title: HPR1392: Beginner's guide to the night sky
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr1392/hpr1392.mp3
Transcribed: 2025-10-18 00:43:13

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We'll be back soon in a year
Hello and welcome to the first episode in a brand new podcast called A Beginner's Guide
to the Night Sky, with me McNalloo, also known as Andrew. It's been well or good number
of decades that I've been interested in astronomy and it's been at least two decades that
I've been giving lectures in astronomy in a professional capacity and given that I've
done a few other podcasts I thought it was high time that I did one in my home ground
which is astronomy. So these aren't going to be lectures as such, you don't mean them
like that but a personal view on how I see the night sky, the stars, the planets, the
galaxies, the universe, the whole lot of it, informed and possibly misinformed by all the
scientific information that we've gleaned about it in the last 100 years. So let me start
as a personal journey with my own recollection of first looking at the night sky. It's a rather
strange memory. It involves looking up at the stars and also looking up at the same time
at snowflakes that were falling down. Now this is a childhood memory, I can date it to about the
years where I was five, six or seven, I can't be precisely sure when it was and like all memories
it's probably unreliable especially in that it's impossible that it was snowing and that I was
seeing the stars at the same time. Well it's nearly impossible because if it's snowing it'll be
cloudy and you can't see the stars. Now it is just about possible that there's a gap in the clouds
or something like that but that's not in fact what I think happened. I think that associated with
this memory I have a memory of it being a snowy evening, snow had fallen and I was in the back
garden of my parents' second house which is how I know roughly when this occurred and I was looking
up at the sky because I discovered that if I reached up and grabbed this washing line that was
strong between two posts and if I grabbed it and released it and it pinged up into the air then I
would get a shower of little snowflakes and therefore I could watch. It's snow lit by the moonlight
whilst the stars were in the background. This is quite a vivid memory that I have. Now there's
more than just a childhood memory there. I think it's the first valuable point that you can make
about the night sky is that we don't really look up. Most of us don't look up or the best we look
up very rarely and in fact our brains are not really geared to look at the night sky and it's
confusing for us in a number of ways and we can illustrate that with a simple illusion. If you look
at the rising moon and I'm looking at the window right now and the sun has just set
20th of November when I am in the Northern Hemisphere Glasgow in Scotland, United Kingdom,
sun has just set, it's what, I don't know, 25 to 5 Greenwich mean time, universal time. The moon is
just rising and while it's sitting there on the horizon it appears larger than it normally does.
Specifically it appears larger than it does when the moon is higher above the horizon so if I come
back in a few hours time I'll be quite satisfied that the moon is now at pretty much normal size
again but for some reason the moon appears to be larger when it's near the horizon. Now you might
be tempted to conclude this is an atmospheric effect and you could test this by taking a series of
photographs of the moon and then superimposing them which is a trivial task using modern software
and what you would find is that you could draw two neat lines on either side of the moon as it
rose up through the sky and those two lines would not get any closer together or further apart
as the night wore on. In other words the moon isn't any larger or smaller at different heights
in the sky. So that would rule out an atmospheric effect. In fact it's actually a sensory effect,
it's the brain plus eyes processing the information that makes us think the moon looks larger when
it's low and that's a symptom of the fact that our brain is really geared up for terrestrial viewing
and not for staining up into the sky. So when with our eyes we look up into the sky we see the night
sky but we have no intuitive idea what distances things are at. So for example if I would have
hold my fist up next to a street light and next to the street light was the moon and next to the
moon was Jupiter and next to Jupiter was a bright star like Aldebaran then all of these things could
be in some senses close to each other as my eye saw them as I viewed it maybe within a few degrees
of each other in fact but the objects involved are at quite different distances and indeed that is
the case in astronomy and we really have no intuitive way of telling when we're just looking at
the sky what distance an object is all our usual cues that we do in everyday life the size of
a known object the graying out effect of the atmosphere the fact that we have binocular vision
two eyes that's of no use to us at all when we're looking at astronomical objects and in fact when
we look up at the sky we see groups of stars there the constellations and the constellations are
groups of stars that just happen to be near each other in the sky and form some kind of shape the
stars in the constellations are in fact nowhere near each other and it's interesting that throughout
history that different peoples in the earth different civilizations different tribes
did him back thousands of years have looked up at some parts of the skies and they've interpreted
the same pattern of stars in much the same way and the most striking example is of Orion now Orion
is a constellation that many people will be familiar with if not just type Orion and you've
into a search engine and you'll soon find find it um but Orion is very noticeably like the figure
of a man uh there's shoulders there's feet and there's a belt okay you have to use a little bit
of imagination but civilizations at different parts different parts of the earth looked up and
identified Orion with a human figure even though those civilizations couldn't have been in cultural
contact let alone any kind of direct contact uh up to thousands of years ago
and it's worth casting our minds over those stretches of time to try and imagine what the very first
humans as we would know them on the earth might have thought of the night sky so these humans haven't
yet got cave painting perhaps they haven't even got to scratching out shapes with a stick in the
sand if so then the sky is their only picture book is their only source of shared art and so it's
not too surprising that the night sky still has quite a resonant mythological relevance to our
modern society it has probably since the first humans looked up at it but uh extends just beyond
the constellations of course because the sky changes as the earth turns giving us day and night
sun rising and setting all stars were rising set too so the whole sky it looks like it's moving
because we're on this revolving globe called the earth and if you look at particular star you'll
notice that it rises earlier from night to night so if you take a particular star you'll find
that it rises four minutes earlier tomorrow night than it does tonight and that incidentally is
because that the earth has moved a little bit further around in its orbit anyway that was not
known to the first people to look up at the sky but they were aware that the sky was changing
and so the picture book the pictures of joining the dots in the sky that they could talk about
and share whatever way they could in these early days it was it was book it had pages that turned
from night to night but more obviously from month to month or season to season however you divided
up the year but not only that you had objects that moved through the sky the moon most obviously
possessed the brightest would appear in a different patch of the sky night after night
and the planets would also move through those same patches of the sky this band of stars or
constellations that encircle the earth through which the moon the planets and the sun move
we call zodiac and there's 12 such constellations and you'd be familiar with most of their names
Taurus, Pisces, Ares, Capricornus, Sagittarius, Aquicoon but they should be
fairly familiar to you when I say them and they're all important because objects of our solar system
pass through these but to the early people on the earth these were far more significance than
just objects in our solar system we didn't know about them as being that of course
they interpret them as being gods or dieties that could walk amongst the stars that had the freedom
to walk amongst the stars so you have for example Mars being tinged red quite obviously in the sky
Mars is identified as a god of war 80s and other mythologies Venus a bright and beautiful object
never far from the sun in the evening or the morning sky the goddess of beauty Venus aphrodite
closest to the sun fleeting and hard to see but fast moving the planet Mercury also known as Hermes
and the slow moving majestic but very bright object that can be at any position in the sky with
respect to the sun not constrained by the bright sun Jupiter the king of the gods also known as Zeus
and so these planets animate the sky and have populate the story but with characters for the
the ancient people upon this earth now these days we don't believe in mythology well most of us
don't believe in that mythology we might believe in other mythology and I personally don't believe in
any particular mythology and some of these myths that are associated with the stars seem somewhat
ridiculous now did the Egyptians really identify the the Great Bear or Sir Major known as the Big
Dipper once I did the Atlantic but where I am most commonly known as the Plow did the Egyptians
really look at that and see an elephant with a crocodile's head and a man standing in its back
what were they on so the pictures in the sky are certainly subjective to us but as I'm tempted
to laugh at some of these old mythologies and it seems incredible to me that astrology is
applied in popular culture just now could have any credence I can't dismiss their importance
and significance to science in history because they are artifacts from the early stages of the
scientific process and the scientific process in some senses being a refined version of the way
humans think anyway and the first part of the scientific process is just noticing that there's
something interesting there and then you collect observations you notice which constellations say
the moon passes through and then you start to classify them you start to give the constellations
names and you start to record how many days it takes for Jupiter to move from one point in the sky
to another and so forth and slowly you build up theories which you then go back and test against
your observations and of course it took us from the first humans look here at the stars and
see those pictures took us millennia to figure out there was a pattern to these motions and then
it's only in the last few hundred years that we developed any kind of mathematical scientific
theory to describe them but nevertheless astrology and just being interested in the
stars whatever reason does sit at the base of modern science and although I wouldn't like to think
of modern science being anything like astrology perhaps one day the cornerstones of
our modern scientific understanding such as relativity quantum mechanics both very important
in the subject of astronomy now or should I say astrophysics now perhaps in thousands of years
time maybe millions of years time humans will look back at on those as quaint
rather well pseudo scientific ideas that work quite far away from the reality of the universe
as we may view astrology today
well there's a lot more I could say about the various things I've touched on in particular
at distance there's a lot more discussion I could talk about parallax and I will talk about parallax
but not in this episode I want to keep these episodes nice and short so next time in episode two
of beginner's guide to the night sky I'm going to start exploring the constellations and
discussing the free and open source software still area and also some apps that you can use on
your phone so that you can begin to find your way around the night sky well that's it for this time
and please visit the website astro.micnellu.net and you'll find other episodes of this podcast show
notes links to other interesting things and also the license under which this podcast is released
which will be some kind of creative comments license having quite the side of which one yet
but that will appear in the website so thank you very much for listening and I hope to
talk to you again in episode two
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