Transcript AurorasAlight

AURORAS ALIGHT!
Presented by:
Dr. Nahide Craig and Dr. Vassilis Angelopoulos
Contributions by:
The scientists and engineers behind the THEMIS team
URL: http://ds9.ssl.berkeley.edu/themis
William L. Valentine Elementary School Science Fair - February 15, 2005
OUTLINE
• What are Auroras?
• Where can you see them?
• What makes them happen?
• Does our Sun have anything to do with it?
• How does a space mission study Auroras?
William L. Valentine Elementary School Science Fair - February 15, 2005
What are Auroras?
What colors do you see?
How far up in the sky do
you think these colors are?
William L. Valentine Elementary School Science Fair - February 15, 2005
Beautiful Dancing Lights in the Sky…
William L. Valentine Elementary School Science Fair - February 15, 2005
… have fascinated people from pre-historic times…
Cro-Magnon cave-paintings: “macaronis” may be earliest depiction of aurora (30,000 B.C.)
William L. Valentine Elementary School Science Fair - February 15, 2005
… and have given rise to mythological creatures, have driven
folklore, and have influenced the course of history, religion and ar
“Fu-Pao, the mother of the Yellow
Empire Shuan-Yuan, saw strong
lightning moving around the star Su,
which belongs to the constellation of
Bei-Dou, and the light illuminated the
whole area. After that she became
pregnant.”,William
OldestL.written
Valentine auroral
Elementary School Science Fair - February 15, 2005
citing, 2600 B.C., China.
The Sun
• The Sun is the closest star,
close-enough to feel its heat.
• The stars are other Suns but very far away.
• The Sun is a giant ball of very hot gas that
shines under its own power.
• The Sun is 109 times the diameter of Earth.
• Over 1,000,000 Earths could fit inside the Sun
• The Sun’s light is not smooth but has spots.
This is the second clue we have that
our Sun is, in fact, quite temperamental!
William L. Valentine Elementary School Science Fair - February 15, 2005
It all starts at the SUN
Today we know that the
auroral lights are the first clue
we have that:
our planet is under attack!!
not by space aliens but by our
very our own star: The Sun.
William L. Valentine Elementary School Science Fair - February 15, 2005
The SUN we feel and cannot feel
We can sense the quiet,
steady Sun which gives us
beautiful sunsets…
…but seen up-close, by our extended
senses, our instrument sensors, the
Sun is wildly active, explosive!
William L. Valentine Elementary School Science Fair - February 15, 2005
Satellites, like the ones on the left, carry our sensors in
space, above the Earth’s atmosphere to:
• Image the Sun free from the blurring of atmosphere’s haze, and
• Measure the gas in the environment between the Sun and Earth
William L. Valentine Elementary School Science Fair - February 15, 2005
Loopy Flares!
What do the shapes you see in the movie remind you of?
William L. Valentine Elementary School Science Fair - February 15, 2005
Magnetic loops – They are everywhere!!
Bar magnet guides iron filings (iron dust) in loops between North (N) and
South (S) poles (Two poles = a dipole). Opposite poles attract, like
poles repel. Many dipoles make a mess!!
Sun’s magnetism also guides its outer layers (solar particles) in loops.
Sun’s dipoles move because Sun’s surface is in motion. Many dipoles
together flare up!
William L. Valentine Elementary School Science Fair - February 15, 2005
Magnetism exists both at Sun and Earth (dynamo)
William L. Valentine Elementary School Science Fair - February 15, 2005
Earth’s “Magnetic Tail” – Magnetotail,
Shaped by the Solar Wind
Our Sun throws off dense clouds of super-hot
gas that sail across the solar system and slam
into Earth at a million miles per hour!
The Earth’s magnetic field looks something like a
comet with Earth at the head of the comet and a long
(million-mile) magneto-tail flowing out behind Earth.
William L. Valentine Elementary School Science Fair - February 15, 2005
Aurora: Why does it happen at night?
When the solar wind passes Earth, it drags the
magnetic tail far out into space and
compresses it.
Stretched magnetic lines break and then (re)
connect into a different shape.
When this happens, magnetic field lines snap
towards Earth like stretched rubber-bands.
Gases guided by the magnetic field speed up
towards Earth and hit the upper atmosphere
at the North and South poles of Earth.
William L. Valentine Elementary School Science Fair - February 15, 2005
Aurora: Where does the light come from?
In a split second, each atom gives off a
tiny burst of light in colors of red,
blue, green or yellow.
When the light is added together, it forms
beautiful curtains of shimmering light
in the sky that we see as Aurora.
William L. Valentine Elementary School Science Fair - February 15, 2005
WHAT Do We Not Know?
Where in the Magnetotail does the
magnetosphere snap and then pop with Aurora?
(snap-crackle-pop? or crackle-pop-snap?)
crackle
snap
pop
William L. Valentine Elementary School Science Fair - February 15, 2005
Why Different Colors??
Our atmosphere has both oxygen and nitrogen:
Oxygen glows in green-yellow and the deep red
Nitrogen glows in blue and the purplish-red.
William L. Valentine Elementary School Science Fair - February 15, 2005
How does THEMIS answer this question?
Ground based observatories
completely cover North American
sector; determine auroral breakup
within 1-3s …
… while THEMIS’s space-based probes
determine the time and location of the activity
in space within <10s.
: Ground Based Observatory
William L. Valentine Elementary School Science Fair - February 15, 2005
Mission Characteristics
• THEMIS is scheduled to be launched with a
Delta II rocket in the fall of 2006.
• THEMIS has five probes (one is in-orbit spare)
and
has a 2 year lifetime.
• THEMIS’ five identical probes measure
particles and fields in orbits which align in the
magnetotail every 4 days over North America.
William L. Valentine Elementary School Science Fair - February 15, 2005
THEMIS Five-Probe Deployment
William L. Valentine Elementary School Science Fair - February 15, 2005
Boom Deployments
William L. Valentine Elementary School Science Fair - February 15, 2005
How is it built? Testing Chamber
William L. Valentine Elementary School Science Fair - February 15, 2005
Scientist John Bonnell: How is the Boom tested?
William L. Valentine Elementary School Science Fair - February 15, 2005
Removal of the Axial Electric Field Boom
William L. Valentine Elementary School Science Fair - February 15, 2005
Magnetometer Booms Tested for Deployment
William L. Valentine Elementary School Science Fair - February 15, 2005
Wire Booms Delivered for Integration to Probes
William L. Valentine Elementary School Science Fair - February 15, 2005
Probe Structure
Probe Carrier Structure
William L. Valentine Elementary School Science Fair - February 15, 2005
Informal Education Programs.
E/PO Web Site: http://ds9.ssl.berkeley.edu/themis
•Aurorae
Gallery
•Activities
•News & Events
•In The
Classroom
•Mission
Science
•About Us
William L. Valentine Elementary School Science Fair - February 15, 2005