TWINKLE, TWINKLE
We talked previously about stars being big balls of gas that burn and
create their own light.
They look very bright in the sky at times, but they are very far away
from Earth.
The closest one (other than the Sun) is about 4.243 light years away
(Proxima Centauri)
Again,
___________
are the distance light travels in one calendar year.
In space, light travels at a constant speed of
________________
!
UP ABOVE THE WORLD SO
BRIGHT
_____________
– the amount of energy
produced by a star each second.
A star’s brightness is measured on a
numbered scale where the
______
has a
luminosity of
___
.
_________
, named after the Greek word
Seirios which means “scorcher” or
“glowing”, is the brightest star in the sky
and has a luminosity of
___
, which means
it is 22 times more bright than the Sun.
Sirius and other stars only appears
dimmer than the Sun because they are
much further away from Earth.
APPARENT MAGNITUDE
_______________________ – is a measurement of how bright an object is when viewed
from the Earth; depends on luminosity and distance
The scale used increases in brightness by a factor of ____.
When the numbers on scale used decreases, that means the object is getting brighter. The Sun has an apparent magnitude of _____ and Sirius has an apparent magnitude of
______
Based on these numbers, it means that the Sun appears brighter than Sirius when
viewed from Earth.
The dimmest celestial objects you can see with your eye have an apparent magnitude
DENEB – BRIGHTEST STAR
IN CYGNUS
Deneb is the brightest star in the constellation
Cygnus. Deneb has an apparent magnitude of
1.3 and. Sirius has an apparent magnitude of
-1.5. Is Deneb brighter or dimmer than Sirius?
ABSOLUTE MAGNITUDE
To be better compare stars, scientists compare
their brightness based on if they were the same
distance from the Earth.
____________________
– a measurement of how
bright an object would be if it were 33 light years
from Earth.
Just like the apparent magnitude scale, the
brightness of a celestial object increases as the
numbers decrease on the scale.
The absolute magnitude of Sirius is
____
and the
APPARENT VS. ABSOLUTE
MAGNITUDE
Which of the two measurements is more
useful? Why?
COLOUR & TEMPERATURE
Reddish stars are the coolest
Bluish-white stars are the hottest
In Orion the Hunter, you can see the difference in colours clearly
Betelguese is about 3000°C and looks reddish.
Rigel is blue-white and is about 11 000°C
Our sun appears
yellowish-white and is in between the two colours for stars.
PLOTTING
STAR
PROPERTIE
S
•
Stars are
grouped based
on where they
are on the
graph.
•
There are red
giants, blue
giants, white
dwarfs, blue &
red supergiants
THE SUN – OUR PERSONAL
STAR
In the past, people thought the sun was a white smooth glowing
ball.
We now know that the sun is actually made of many layers, which
each level performing different activities.
It is completely made of gas, with no solid surfaces, but it still has
a definite structure.
In the core, nuclear reactions occur that fuse (join) atoms of
hydrogen (H) to create helium (He) causing the Sun’s core to reach
15 000 000°C
____________________
– reactions that change the nuclei (plural for
CORE TO ATMOSPHERE
Energy from the Sun’s
______
moves outward in to the
____________
zone
Energy continues to move outward in to the
______________
zone, where
cool matter sinks and hot matter rises.
The energy continues to move outward until it reaches the Sun’s
surface, the
__________________
, where Energy escapes as light.
The area above the Photosphere is called the
______________________
,
divided in to 2 sections:
_________________ – inner atmosphere and is very hot at about 60 000°C hotter than the photosphere
___________ – extremely hot ionized gases called plasma that glow brightly and extends millions of kilometres in to outer space (can be seen during a solar eclipse)
SUN’S SURFACE
Using telescopes, scientists were able to
figure out that the Sun does not have a
smooth surface.
400 years ago, Galileo studied Sunspots with
his telescope.
_________
– a dark area on the Sun’s surface
that is cooler than the area surrounding it,
caused by the Sun’s magnetic field
They vary in both size and regularity and will
usually appear with in pairs with opposite
polarity (North and South poles)
_____________
–gases and charged particles
that are blasted above an active region of the
Sun’s photosphere
ENERGY FROM THE SUN
Every second, the Sun releases enough energy to meet the
needs of every human for the next
_____________
years.
It has a huge affect on our climate, weather, and provides the
energy we need to survive on Earth.
The following is a list that describes a few ways the Sun directly
or indirectly affects our lives:
Plants use the light from the Sun grow and produce food
Animals eat plants that are grown from sunlight
Coal was formed from the remains of prehistoric plants, so it is a form
of stored energy from the Sun.
Oil, including gasoline, is formed from the remains of prehistoric
AURORAS
The corona constantly releases electrically charged particles in to space up to _____ km/s called ________________.
Earth is surrounded by an atmosphere that contains atoms of different gases and
a magnetic field.
Particles of solar wind spiral along the lines of the magnetic field sometimes
contacting the gases in the atmosphere as it travels towards the poles.
___________ – coloured lights in the sky produced when the solar wind comes in
contact with Earth’s magnetic field and the atmosphere.
These can be produced as high as 400 km above Earth’s surface and can be
seen at night at the North and South poles on Earth.
Over the North pole, it is called ____________________ (Northern Lights) and in at
the South pole, it is called _________________________ (Southern Lights).
