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OUR SUN Unusually active the past 2 weeks Very beautiful.

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Presentation on theme: "OUR SUN Unusually active the past 2 weeks Very beautiful."— Presentation transcript:


2 OUR SUN Unusually active the past 2 weeks Very beautiful

3 Kind of Sun to choose this week

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

5 Sunspot Cycle

6 Corona Changes with No. Spots

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

8 Today - Solar surface (Photo sphere)

9 Today Corona (2.0 MK)

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

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

12 ? Effects on the Earth

13 Aurora

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

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

16 Magnetic Field from SOHO

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

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

19 Outer Corona: from SOHO

20 Movie

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

22 Movie

23 Magnetic field at York Normal variationVery Stormy

24 Aurora in St Andrews (Tom Robitaille) Wed

25 Thurs

26 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.

27 3. Cause of Aurora

28 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).

29 At core of process is reconnection Reconnection converts energy

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

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

32 Aurora pictures taken from the Space Shuttle Height of auroral emission: 100-400 km (60 - 200 miles)

33 Aurora from Space - today

34 Solar Wind Properties Now

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

36 Numeric al Model Magnetic Catastro phe

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

38 Reconnection continues - loops rise

39 (Priest and Schrijver 1999)

40 Example from SOHO

41 Example from TRACE

42 5. This Week - Fireworks Continued SOHO Site (Nov 6): Just as solar scientists were ready to start breathing normally again, active region 10486 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.

43 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, 2003--the day of the biggest explosion ever recorded in our solar system.

44 X-ray intensity as function of time


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

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

48 Nov 4 EIT 284 (2.0 MK) every 6 hours

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




53 So Enjoy the Sun and keep looking out for aurorae


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