OUR SUN Unusually active the past 2 weeks Very beautiful

Kind of Sun to choose this week

CONTENTS 1. SOHO 2. Last Week’s Mass Ejection 3. Cause of Aurora 4. Cause of Flare 5. This Week’s Flare

Sunspot Cycle

Corona Changes with No. Spots

1. SOHO (Solar Heliospheric Obs y ) Orbiting Sun at L1 point in phase with Earth Observing Sun continuously for first time

Today - Solar surface (Photo sphere)

Today Corona (2.0 MK)

SOHO Coronagraph -- Artificial eclipse Can reach Earth -> profound effects Discovered huge mass ejections

Spoof Information propagates from the left w. very little interference !

? Effects on the Earth

Aurora

Other Consequences Damage to satellites, astronauts Disruption to radio/phone communications, power grids

Photo sphere from SOHO 2. Event of October 28-29

Magnetic Field from SOHO

Corona: (2 MK) An X-17 flare (3rd)

X-ray Intensity Observed by Earth Satellite (C, M, X-flares)

Outer Corona: from SOHO

Movie

Outer Corona further out 2000 km/s (5 times faster than normal CME)

Movie

Magnetic field at York Normal variationVery Stormy

Aurora in St Andrews (Tom Robitaille) Wed

Thurs

Some Effects Aircraft crossing north Atlantic were confined to narrow corridor to minimise radiation. Astronauts on board Space Station took shelter in its most shielded section. Two Japanese satellites malfunctioned. Engine of Smart 1 shut down.

3. Cause of Aurora

The Magnetic Field of the Earth The Earth’s magnetic field is like that of a bar magnet close to the Earth The solar wind distorts the magnetic field into a comet like shape on the nightside (the magnetotail).

At core of process is reconnection Reconnection converts energy

Effect of Coronal Mass Ejection on Earth - when IMF southward it can reconnect

The auroral oval from space From space, one can see that the aurora occurs in an oval around the north pole.

Aurora pictures taken from the Space Shuttle Height of auroral emission: km ( miles)

Aurora from Space - today

Solar Wind Properties Now

4. Overall Picture of Flare Magnetic tube twisted - erupts - drives reconnection

Numeric al Model Magnetic Catastro phe

Reconnection proceeds -- loops rise Chromosphere Reconnection heats loops/ribbons

Reconnection continues - loops rise

(Priest and Schrijver 1999)

Example from SOHO

Example from TRACE

5. This Week - Fireworks Continued SOHO Site (Nov 6): Just as solar scientists were ready to start breathing normally again, active region blasted off yet another mega-flare. This one saturated the X-ray detectors on the NOAA's GOES satellites; the jury was therefore out for a while on the definitive classification of the flare. Speculations ranged from X20 to X40 or even X50. Today word came that the best estimate is X28. It is now official: We have a new number 1 X-ray flare for the record books.

SpaceWeather.Com: SUPERFLARE: Giant sunspot 486 unleashed another powerful solar flare on Nov. 4th (1950 UT). Ionizing radiation hit Earth's atmosphere soon after the explosion and caused a severe radio blackout, which radio listeners noticed across North America. Astronomers won't soon forget Nov. 4th, the day of the biggest explosion ever recorded in our solar system.

X-ray intensity as function of time

Nov 4 EIT 304 (80,000 K) every 5-6 hours

Nov 4 EIT 195 (1.6 MK) 1st 5 hours

Nov 4 EIT 284 (2.0 MK) every 6 hours

Compare Temps 80,000 K, 1.6 MK, 2.0 MK

LASCO C2

LASCO C3

6. IN FUTURE -- MAYBE:

So Enjoy the Sun and keep looking out for aurorae