william l. valentine elementary school science fair - february 15, 2005 auroras alight! presented...

William L. Valentine Elementary School Science Fair - February 15, 2005

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


• 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?

OUTLINE


What are Auroras?

What colors do you see?

How far up in the sky do you think these colors are?


Beautiful Dancing Lights in the Sky…


Cro-Magnon cave-paintings: “macaronis” may be earliest depiction of aurora (30,000 B.C.)

… have fascinated people from pre-historic times…


“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 thewhole area. After that she became pregnant.”, Oldest written auroral citing, 2600 B.C., China.

… and have given rise to mythological creatures, have driven folklore, and have influenced the course of history, religion and art.


• 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 thatour Sun is, in fact, quite temperamental!

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.

It all starts at the SUN


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!


• Image the Sun free from the blurring of atmosphere’s haze, and• Measure the gas in the environment between the Sun and Earth

Satellites, like the ones on the left, carry our sensors in space, above the Earth’s atmosphere to:


Loopy Flares!

What do the shapes you see in the movie remind you of?


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!


Magnetism exists both at Sun and Earth (dynamo)


Earth’s “Magnetic Tail” – Magnetotail, Shaped by the Solar Wind

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.

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!


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.

Aurora: Why does it happen at night?


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.

Aurora: Where does the light come from?


Where in the Magnetotail does the magnetosphere snap and then pop with Aurora? (snap-crackle-pop? or crackle-pop-snap?)

WHAT Do We Not Know?

pop

snap

crackle


Our atmosphere has both oxygen and nitrogen: Oxygen glows in green-yellow and the deep redNitrogen glows in blue and the purplish-red.

Why Different Colors??


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

How does THEMIS answer this question?


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) andhas 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.


THEMIS Five-Probe Deployment


Boom Deployments


How is it built? Testing Chamber


Scientist John Bonnell: How is the Boom tested?


Removal of the Axial Electric Field Boom


Magnetometer Booms Tested for Deployment


Wire Booms Delivered for Integration to Probes


Probe Carrier Structure

Probe Structure


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 auroras alight! presented...

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