Greetings and welcome to the
Introduction to Astronomy.
One of the things that I like
to do in each of my introductory
astronomy classes is to begin
the class with the astronomy
picture of the day from
the NASA website that is
APOD.NASA.GOV/APOD.
And today's picture for
October the 31st of 2019.
Well is titled The
Ghostly Veil Nebula.
So what do we see here?
Well, this is an example
of a supernova remnant.
And this is not the
way we normally see it.
This is actually
the entire nebula.
We often see parts of this.
And that's because it is
such a large nebula extending
across a good sized
portion of the sky.
How large.
Well, this would be about six
full moons or three degrees
in the sky, which
is incredibly large
and you can imagine that if
you could put six full moons
across this that
would be how large it
would appear in the sky.
Now it's not something
you'd be able to see
with your naked eye.
It would be far too faint
but it is that large
and extends that much.
So of an individual portions of
this are given their own names.
So it actually looks as
several different nebulae.
And one of the common ones down
to the lower right hand side
is actually the
Witch's Broom Nebula.
So a number of - And there
are a number of other ones
within here as well.
That's one of the
prominent ones and one
that ties in with Halloween.
So what this is an
example of a supernova
remnant or an exploded star.
Now we see a number of these
across the sky when stars reach
the end of their life.
They can explode and it
depends on the exact mass
of the star very
low - very mass -
massive stars will
eventually explode and expel
a lot of material
out into space.
There are a couple of
ways this can happen.
So there are two - two
major types of supernovae.
One is a massive star
at the end of its life.
The other is an
already compact star
the remnant left over that
becomes unstable and explodes.
So there are a couple
different ways this can occur,
but they both do send
material back out into space.
Now this is where the
heavy elements come from
or at least many of them.
How do we produce all
of these heavy elements.
Well, the big bang produced
hydrogen and helium
and that was it heavier elements
had to be created within stars.
So stars fuse
hydrogen into helium
and then helium into carbon.
And so on up to iron in order
to create elements heavier
than iron.
You need something more massive
some massive source of energy.
So a large supernova explosion
produces a lot of energy
and would be able to create
those heavier elements
things like gold up to uranium
that are much heavier elements
and would then also then
expels them back out
into the universe.
So the heavier
elements here on Earth.
And within our bodies were once
a part of a supernova and that
would have been
enriched the material
from which future generations
of stars could have formed.
So many of these
supernovae going off early
in the history of the universe
would have enriched material
for future generations of stars
to be able to form planets
like the Earth.
So that was our picture of
the day for October the 31st
of 2019.
It was titled The
Ghostly Veil Nebula.
We'll be back again tomorrow
for the next picture.
So until then have a
great day, everyone.
And I will see you in class.
