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Date: 20 Sep 2006 22:09:31
From: Sam Wormley
Subject: increase in auroral activity on the coming weekend
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We expect that the coronal hole on the sun that is facing Earth will lead to
some increase in auroral activity on the coming weekend.
Our predictions of this increase in auroral activity have been one day early
for the past two solar rotations. Aurora watchers should check the sky on
Friday Sept 22, but be aware that the high speed stream producing the
activity may be one or two days late.
We expect this activity to be visible over Canada, Alaska, the northern tier
of states in the USA, Scandinavia, and northern Russia. It may be visible
low on the southern horizon from Tasmania and southern New Zealand. (Kp 4 to
6).
Dr. Charles Deehr, Prof. Emer. Phys. Ph. 907 474 7473 Fax 907 474 7290
email cdeehr@gi.alaska.edu
The Geophysical Institute
University of Alaska Fairbanks
903 Koyukuk Ave N
Fairbanks, Alaska 99775-7320
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Date: 20 Sep 2006 16:59:09
From: canopus56
Subject: Re: increase in auroral activity on the coming weekend
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Sam Wormley wrote:
> We expect that the coronal hole on the sun that is facing Earth will lead to
> some increase in auroral activity on the coming weekend.
<snip >
Additionally, the autumnal equinox is on Sept 23 04:03UTC. At this
point the Earth passes through the ecliptic and an area of increased
solar wind. In a similar position a few days before the 2006 vernal
equinox, one day of good low latitude auroras occured. See the
Spaceweather.com entry site for March 18, 2006.
Aurora occur more frequently around the equinoxes:
http://science.nasa.gov/headlines/y2002/23sep_auroraseason.htm
http://science.nasa.gov/headlines/y2001/ast26_1.htm
- Canopus56
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Date: 21 Sep 2006 00:59:44
From: Stuart Levy
Subject: Re: increase in auroral activity on the coming weekend
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On 2006-09-20, canopus56 <canopus56@yahoo.com > wrote:
> Sam Wormley wrote:
>> We expect that the coronal hole on the sun that is facing Earth will lead to
>> some increase in auroral activity on the coming weekend.
><snip>
>
> Additionally, the autumnal equinox is on Sept 23 04:03UTC. At this
> point the Earth passes through the ecliptic
How's that, again??
> and an area of increased
> solar wind. In a similar position a few days before the 2006 vernal
> equinox, one day of good low latitude auroras occured. See the
> Spaceweather.com entry site for March 18, 2006.
>
> Aurora occur more frequently around the equinoxes:
> http://science.nasa.gov/headlines/y2002/23sep_auroraseason.htm
> http://science.nasa.gov/headlines/y2001/ast26_1.htm
That is funny. Given that Earth's magnetic poles aren't very close
to its rotational poles (which define the equator that the sun's
about to cross), I'm surprised it makes a difference. Can you or anyone
explain why?
Now, if it happens to be the case that the RA = 0h/12h line,
where Earth is at the equinoxes, happens to lie near the *sun*'s
equator, that would be interesting. But I don't think that's the case.
(A solar rotation applet shows that the current B_0, inclination
of the sun's rotation axis to the plane of the sky, is about 6.9
degrees, near the maximum.)
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