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The Sun is the most prominent feature in the solar system

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Title: The Sun is the most prominent feature in the solar system


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  • The Sun is the most prominent feature in the
    solar system
  • It contains about 98 of the total mass of the
    solar system
  • The interior of the Sun can hold over 1.3 million
    Earths

3
Birth of the Sun
  • The Sun was formed around 4.6 billion years ago
    within a protoplanetary disc of gas and dust
  • The central regions of the disc began to coalesce
    and collapse
  • When the Sun had contracted enough, nuclear
    reactions began at the core, causing the Sun to
    shine as a star

An artists image of a protoplanetary disc
4
  • The Sun has been active for 4.6 billion years and
    has enough fuel at its core to burn for another 5
    billion years
  • The Sun rotates every 25 days at the equator to
    every 36 days at the poles
  • Deep down everything appears to rotate every 27
    days

5
  • The Sun is called a main sequence star
  • Stars in the main sequence spend most of their
    active lives in a stable state fusing hydrogen to
    helium
  • Bigger stars fuse hydrogen to helium at a faster
    rate and live shorter lives
  • Smaller stars fuse hydrogen to helium at a slower
    rate and live longer lives

The vast majority of stars lie in the main
sequence
6
  • The Sun orbits the center of the Milky Way Galaxy
    in the same way as the Earth orbits the Sun
  • It takes about 250,000 million years to complete
    one orbit traveling at approximately 250
    kilometers/second

7
  • The Suns outer layer is called the photosphere
  • It has a temperature of 6000oC (11,000oF)
  • Its mottled appearance is due to turbulent
    eruptions at the surface
  • Sunspots appear in the area of the photosphere

8
Sunspots
  • Sunspots are dark depressions on the photosphere
    with a temperature of 4000oC (7000oF) which is
    cooler than the surrounding area
  • Sunspots change over a period of days and move
    across the Sun as it rotates
  • They have a strong magnetic field associated with
    them and last from a few days to a few weeks

9
  • Faculae are bright luminous hydrogen clouds
    which form in the photosphere near sunspots
  • They put out more radiation than normal and
    increase the solar irradiance
  • While sunspots make the Sun look darker, faculae
    make it look brighter

Faculae
10
  • Solar energy is created deep within the core
  • Here the temperature is 15,000,000oC
    (27,000,000oF)
  • The pressure is so intense that nuclear reactions
    take place
  • Energy is carried to the surface by both
    radiation and convection

11
  • The pressure at the
  • Suns core is so intense
  • that it causes hydrogen
  • nuclei to fuse together
  • to form one helium nucleus
  • The difference in mass is expelled as energy
  • It is carried to the Suns surface by radiation
    and convection and is released primarily in the
    form of electromagnetic radiation (i.e. light)
  • Energy produced in the core takes a million years
    to reach the surface

Nuclear Reactions In the Core
12
  • Convection occurs because heated fluids, due to
    their lower density, rise and the cooled fluids
    fall
  • The heated fluid will rise to the top of a
    column, radiate heat away, then fall to be
    reheated, rise and so on
  • A convection cell forms when a packet of fluid
    becomes trapped in this cycle
  • Very large convection cells on
  • the Sun show a pattern that
  • looks like rice grains, called
  • granulation

Convection
granulation cells
13
  • The chromosphere is above the photosphere where
    temperature is between 6000C and 20,000 C
  • Solar energy passes through this region on its
    way from the core
  • Spicules and solar flares arise in the
    chromosphere

14
Spicules
  • The chromosphere contains spikes of superheated
    gas called spicules that rise through it
  • Spicules are short-lived phenomena corresponding
    to rising jets of gas that move upward at high
    speed usually lasting only 10 minutes
  • More than 100,000 spicules tickle the solar
    atmosphere at any time

15
Solar Flares
  • Solar flares are eruptions in the chromosphere
  • High energy particles and gasses are emitted
    lasting minutes to hours
  • Flares produce sunquakes similar to an 11.3
    magnitude earthquake on Earth and release 40,000
    times more energy than the 1906 San Francisco
    earthquake

Image taken by SOHO in 1999
16
Corona
  • The corona is the outer part of the Suns
    atmosphere with extremely high temperatures
    around 1,000,000C (1,800,000F)
  • The outer region of the corona stretches far into
    space and consists of particles traveling away
    from the Sun
  • The corona can only be seen during a total solar
    eclipse

17
Solar Eclipse
  • A solar eclipse happens when the moon passes
    between the Sun and the Earth
  • The corona is a million times fainter than the
    surface of the Sun so the only time it can be
    seen is during a total exlipse
  • Ancient people often thought that eclipses were
    signs from angry gods or omens of doom

18
Prominences
Prominences
  • A solar prominence, or filament, is an arc of gas
    that erupts from the sun
  • They can loop thousands of miles into space
  • They are held above the Suns surface by strong
    magnetic fields and can last many months
  • Prominences are larger than the Earth, which
    would easily fit under it

Prominences on the Sun, with the Earth shown to
scale
19
Coronal Mass Ejections
  • Coronal Mass Ejections (CMEs) are huge bubbles
    of plasma ejected from the Sun
  • Solar plasma is heated to tens of millions of
    degrees and electrons, protons, and heavy nuclei
    are accelerated to near the speed of light
  • The CMEs disrupt the solar wind and can strike
    the Earth disrupting communication and navigation
    systems, satellites and power grids, sometimes
    with catastrophic results

20
  • Solar winds are streams
  • of highly ionized gas that
  • blow continuously outward
  • through the Solar System
  • The temperature of the
  • corona is so high that the Sun cannot hold on
    to it and the solar winds stream from the Sun at
    one million miles per hour
  • This distorts the Earths magnetosphere

Solar Wind
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  • Flares and CMEs are the most powerful particle
    accelerators in the solar system
  • A CME can erupt with the energy of 200 billion
    Hiroshima bombs
  • Radiation from a flare could kill a spacewalking
    astronaut
  • The Earths magnetosphere shields us from these
    energetic particles

Solar Wind
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The Aurora Borealis
  • The aurora dances in the polar regions as the
    solar wind interacts with the Earths magnetic
    field and energizes electrons and ions in the
    Earths upper atmosphere
  • The energized molecules and atoms in the thin
    polar atmosphere then glow at different colors

23
The Future of the Sun
  • The Sun has enough fuel to last for another 5
    billion years
  • At the end of its life it will have used up all
    its hydrogen
  • When there is no longer any source of heat to
    balance gravity its core will then collapse

24
  • This collapsed core will become compressed and
    heated causing it to produce a new surge of power
    (from the burning of helium into carbon at the
    core and hydrogen into helium in shells around
    the core) and begin to swell
  • This phase is called a red giant and it will
    ultimately grow so large it will swallow the Earth

The Future of the Sun
25
The Future of the Sun
  • After about a billion years as a red giant it
    will shed its outer layers forming a planetary
    nebula (which, by the way, has nothing to do with
    planets)
  • The planetary nebula phase is fleeting and lasts
    only about 10,000 years

This is the Helix Nebulaan example of a
planetary nebula
26
  • Having run out of fuel the core of the Sun will
    shrink to a hot (30,000C) white dwarf only a
    few thousand miles in diameter
  • A white dwarf is a stable star held up by
    electron degeneracy pressure, an exotic state of
    matter
  • It will radiate left-over heat for billions of
    years until it cools to a black dwarf
  • A black dwarf is a cold dark mass that has no
    internal source of energy

The Future of the Sun
27
  • SOHO (The Solar Heliospheric Observatory) was
    launched on December 2, 1995 by NASA and the
    European Space Agency (ESA)
  • It became operational in March 1996 and was meant
    to operate until 1998 but has been so successful
    that its mission has been approved until 2007

SOHO
28
SOHO
  • SOHO is designed to study the internal structure
    of the Sun, its outer atmosphere, and the origin
    of the solar wind
  • It helps us understand the interactions between
    the Suns and the Earths environment better than
    ever
  • It provides uninterrupted views of the Sun and
    may help solve some puzzling riddles of our
    closest star

29
  • Mankind will not remain on Earth forever, but in
    its quest for light and space will at first
    timidly penetrate beyond the confines of the
    atmosphere, and later will conquer for itself all
    the space near the Sun. - Konstantin E.
    Tsiolkovsky
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