Comments on: The Sun kick starts its cycle once again

By: SETI and other stuff « Dad2059’s Blog of Science Fiction/Science Fact and Random Acts of Weirdness

Thu, 17 Jan 2008 15:42:32 +0000

[...] http://www.badastronomy.com/bablog/2008/01/14/the-sun-kick-starts-its-cycle-once-again/ [...]

By: Wayne Reed

Wayne Reed — Wed, 16 Jan 2008 17:52:06 +0000

Thank you csrster for the good description,

I have seen several reports on this polarity reversal without mention of how it is determined. I was hoping it was something I could confirm with my H-A PST, but I guess it takes more sofisticated techniques than I can muster.

By: csrster

csrster — Wed, 16 Jan 2008 08:05:25 +0000

Wayne – that’s a damn good question. The polarity of sunspots was first measured by none other than George Ellery Hale whose name most people associate with night-time astronomy (and not only because his name is attached to the big telescope at Palomar). But Hale was also one of the great pioneers of solar astronomy. He is credited as co-inventor of the spectroheliograph, which allows one to make monochromatic images of the Sun.

Magnetic fields can be measured as a result of the Zeeman effect which causes certain spectral lines to be split in a pattern from which the strength and polarity of the magnetic field can be deduced. Hale and his coworkers were the first to determine how the polarity varies within sunspot groups, between the two solar hemispheres, and with time during the solar cycle.

By: Wayne Reed

Wayne Reed — Wed, 16 Jan 2008 02:37:14 +0000

I haven’t observed the sun with my PST since the new cycle started due to lousy weather, but I have one question. How do scientists determine the polarity of an active region or sunspot? It would be difficult to hold a compass up to it to check. Is there some difference that can be detected through a telescope in white or h-a light?

By: Don K

Don K — Tue, 15 Jan 2008 20:09:42 +0000

We are all excited here at the High Altitude Observatory in Boulder (Phil, wanna tour?) about the new solar cycle. A model developed by our scientists (M. Dikpati et al) has predicted that this cycle should be the strongest in over 60 years. Cross your fingers!

We take solar observations in H-alpha and He-I every three minutes from our observatory in Hawaii.

You can check out the latest images at the MLSO homepage. Click on “Data and movies” in the banner to get daily movies.

By: Justin

Justin — Tue, 15 Jan 2008 20:03:05 +0000

“As an aside, who realises that the Earth’s North Pole is actually a magnetic south pole. Think about it. How else would compasses work?”

Interesting…please explain?

By: JackC

JackC — Tue, 15 Jan 2008 14:27:08 +0000

For those asking why this is “Cycle 24: http://en.wikipedia.org/wiki/Solar_cycle

Basically, the early/mid 1800s found Schwabe “discovering” the cycle, and tracking it back in time. It became convention to number the cycle starting in 1755 as “1″