Transcript The SUN!!!!!!!

•The SUN!!!!!!!
The Facts Just the Facts:
1. Center of our Solar System.
2. Spinning ball of hot gas and nuclear
reactions.
3. Lights up the Earth and provides us with
heat.
4. The sun's absolute magnitude (its intrinsic
brightness) is +4.83.
5. Its stellar type is G (a star that absorbs
strong metallic lines in its spectrum).
6. A medium-sized yellow star
7. It’s 149,680,000 km or 1 Astronomical
Unit from the Earth.
. http://www.enchantedlearning.com/subjects/astronomy/sun/
discovery.nasa.gov/ images/sun.jpe
How Close is Close?
• The Earth is closest to the Sun (this is
called perihelion) around January 2 each
year (147.1 million km.)
• It is farthest away from the Sun (this is
called aphelion) around July 2 each year
( 152.6 million km).
http://www.enchantedlearning.com/subj
ects/astronomy/sun/
How Hot is Hot?
• The Sun's core can reach 10 to 22.5 million°F.
The surface temperature is approximately
9,900°F (5,500°C). The outer atmosphere of the
Sun (which we can see during a solar eclipse)
gets extremely hot again, up to 1.5 to 2 million
degrees. At the center of big sunspots the
temperature can be as low as 7300 °F (4300 K,
4000 °C). The temperature of the Sun is
determined by measuring how much energy
(both heat and light) it emits.
http://www.enchantedlearning.com/subjects/astronomy/sun/
What makes up the Sun?
• The Sun is made up of about 2 x 1030 kilograms
of gas. It is composed of about 75% hydrogen
and 25% helium. About 0.1% is metals (made
from hydrogen via nuclear fusion). This ratio is
changing over time (very slowly).
• Since the Sun formed 4.5 billion years ago, it
has used up about half of its initial hydrogen
supply.
• http://www.enchantedlearning.com/subjects/astronomy/sun/
Star Type
• Our Sun is a second or third generation star.
Second generation stars do not just burn
hydrogen, they also burn heavier elements, like
helium and metals (elements heavier than
hydrogen and helium).
• The element helium was named after the Sun
(called "Helios" in Greek) because it was first
discovered on the Sun. Helium is plentiful on the
Sun but rare on Earth.
http://www.enchantedlearning.com/subjects/astronomy/sun/
How does the Sun Produce
Energy?
• At the Sun's core, nuclear fusion produces
enormous amounts of energy, through the
process of converting hydrogen nuclei into
helium nuclei (nuclear fission).
•
http://www.enchantedlearning.com/subjects/astronomy/sun/
• Each second the Sun converts about
600,000,000 tons of hydrogen nuclei into
helium nuclei. These fusion reactions
convert part of these atoms' mass (roughly
4 million tons) into energy, and release an
enormous amount of this heat and light
energy into the Solar System.
•
http://www.enchantedlearning.com/subjects/astronomy/sun/
How long will the Sun continue to
Burn?
• In these fusion reactions, the Sun loses 4
million tons of mass each second. The
Sun will run out of fuel in about 5 billion
(5,000,000,000) years. When this
happens, the Sun will explode into a
planetary nebula, a giant shell of gas that
will destroy the planets in the Solar
System (including Earth).
•
http://www.enchantedlearning.com/subjects/astronomy/sun/
http://imagine.gsfc.nasa.gov/docs/science/know_l1/sun.html
• From the center out, the layers of the Sun
are as follows: the solar interior composed
of the core (which occupies the innermost
quarter or so of the Sun's radius), the
radiative zone, and the convective zone,
then there is the visible surface known as
the photosphere, the chromosphere, and
finally the outermost layer, the corona.
• The energy produced through fusion in the
Sun's core powers the Sun and produces
all of the heat and light that we receive
here on Earth. http://sohowww.nascom.nasa.gov/explore/sun101.html
• All of the energy that we detect as light
and heat originates in nuclear reactions
deep inside the Sun's high-temperature
"core." This core extends about one
quarter of the way from the center of Sun
to its surface where the temperature is
around 15 million Kelvin (K).
• In the innermost shell, right above the
core, energy is carried outwards by
radiation. This "radiative zone" extends
about three quarters of the way to the
surface.
•
http://sohowww.nascom.nasa.gov/explore/sun101.html
• In the outermost of the two shells, where
the temperature drops below 2,000,000 K
(3.5 million degrees F) the plasma in the
Sun's interior is too cool and opaque to
allow radiation to pass. Instead, huge
convection currents form and large
bubbles of hot plasma move up towards
the surface (similar to a boiling pot of
water that is heated at the bottom by a
stove).
•
http://sohowww.nascom.nasa.gov/explore/sun101.html
• The radiation does not travel directly
outwards - in this part of the Sun's interior,
the plasma density is very high, and the
radiation gets bounced around countless
numbers of times, following a zig-zag path
outward. It takes about 170 thousand
years for radiation to make its way from
the core to the top of the radiative zone!
The Sun's Outer Layers
• Collectively referred to as the solar
'atmosphere‘.
• The photosphere, the chromosphere, and
the corona. These three regions have
substantially different properties from each
other, with regions of gradual transition
between them.
http://imagine.gsfc.nasa.gov/docs/science/know_l1/sun.html
http://sohowww.nascom.nasa.gov/explore/sun101.html
The Photosphere
• There is not really a "surface" to the Sun.
• The Sun is a bunch of gas which gets denser
and denser as you move from space toward the
solar core.
• In general is has a pressure about a few
hundredths of the sea-level pressure on Earth, a
density of about a ten-thousandth of the Earth's
sea-level atmospheric density, and a
temperature in the range 4500-6000 Kelvin.
http://imagine.gsfc.nasa.gov/docs/science/know_l1/sun.html
The Chromosphere
• The gases which extend away from the
photosphere make up the chromosphere.
• The chromosphere is about 2500 km thick
• The density of the gases decreases as you
move away from the photosphere into the
chromosphere, but the temperature increases!
From the bottom to the top of the chromosphere,
the average temperature goes from 4500 to
10,000 Kelvin!
• http://imagine.gsfc.nasa.gov/docs/science/know_l1/sun.html
http://imagine.gsfc.nasa.gov/docs/science/know_l1/sun.html
The Corona
• The outermost region of the Sun's atmosphere.
• Extends for millions of miles into space above
the photosphere.
• During a total solar eclipse, the corona shines
beautifully against the dark sky.
• The corona has a density about 0.0000000001
times that of the Earth's sea-level atmosphere.
• It is very hot - millions of Kelvin. Because of this
high temperature, the bulk of the radiation from
the corona is emitted at ultraviolet and X-ray
wavelengths.
http://imagine.gsfc.nasa.gov/docs/science/know_l1/sun.html
Other Solar Features
• Solar Wind: a stream of charged
particles flowing outward from the Sun
with an average velocity of about 400
km/sec. http://imagine.gsfc.nasa.gov/docs/science/know_l1/sun.html
http://www.geo.mtu.edu/weather/aurora/images/sun/sun-flare.jpg
Sunspots and Their Cycle:
• Sunspots are cooler regions on the Sun's
photosphere (about 1500 K cooler) and so
appear to be darker than the photosphere. A
given sunspot can have a lifetime ranging
from a few hours to a few months. It consists
of two parts - the dark inside region called
the umbra the surrounding less dark region
called the penumbra. Their sizes vary over a
wide range, with a few having been
measured to be 50,000 km in diameter!
•
http://imagine.gsfc.nasa.gov/docs/science/know_l1/sun.html
•
Sunspot
Courtesy of ASASand
• Sun spots were first observed
telescopically in late 1610 by Frisian
astronomers Johannes and David
Fabricius, who published a description in
June 1611. At the latter time Galileo had
been showing sunspots to astronomers in
Rome, and Chrisoph Scheiner had
probably been observing the spots for two
or three months. The ensuing priority
dispute between Galileo and Scheiner,
neither of whom knew of the Fabricius'
work, was thus as pointless as it was
bitter.
•
http://en.wikipedia.org/wiki/Sunspot
• A German amateur astronomer, Heinrich
Schwabe, published a paper in 1851
which stated that the number of sunspots
visible on average varied with a period of
about 10 years. This conclusion has been
substantiated by observations over the
140 years since. The period of repetition
on average is 11.1 years, but has been as
short as 8 years and as long as 16 years.
•
http://imagine.gsfc.nasa.gov/docs/science/know_l1/sun.html
• During the maximum of the cycle,
more than 100 sunspots can be seen
on the Sun at once. During the
minima, the Sun sometimes has no
spots at all. This cycle is closely
related to the magnetism of the Sun.
In fact, it is the changing magnetic
field of the Sun which governs many
aspects of solar activity.
http://imagine.gsfc.nasa.gov/docs/science/know_l1/sun.html
Facts
• The Sun has 333,400 times more
mass than the Earth and contains
99.86% of the mass of the entire
Solar System - this means Jupiter
and all the other planets and
asteroids only make up 0.14% of the
mass of the Solar System! In fact just
a pinhead of the Sun's core material
could kill a person 160 kilometres
away.
http://www.solarspace.co.uk/Sun.php
More Facts
•
Each second the Sun loses 4.5 million tons of
material - this means that in 42 million years it
would lose enough material to make the Earth.
However this high loss of mass is really rather
insignificant when compared to the total mass of
the Sun - over the past 4,500 million years it has
barely lost a few hundredths of a percent of its
total mass. http://www.solarspace.co.uk/Sun.php
A Few More Facts
• Interestingly, all the light we see
from the Sun comes from a layer
500km deep (the top 0.1%) and
takes about 8.3 minutes to reach
us down here on Earth. The
radiation does however take
about 170,000 years to make its
way out from the Sun's core.
http://www.solarspace.co.uk/Sun.php
The End