Solar Section        


March 30, 2016

The 2016 Mercury Transit

Have you already made any plans for the Mercury Transit which is coming upon us very fast?  Dr. John E. Westfall, the Coordinator of the Venus and Mercury Section wrote a marvelous article in the Spring Journal of the ALPO about the transit which is to happen on May 9th.  We are encouraging everyone to read this in order to become familiar with what to expect, and if you actually observe or image the event, we always appreciate your submissions for our archive via email to .

In addition, those who might take on the challenge to calculate the length of the Astronomical Unit (distance between the Earth and the Sun), might research the Solar Section’s archive the days after the event to look for the right images captured by individuals separated far enough from each other to extract the data they need for this effort. Follow the link here to download Dr. Westfall’s article.


March 27, 2016

ALPOSS – A report on CR2166 thru CR2168

Do you still remember how active the Sun was in the Summer of last year?   ALPOSS Acting Coordinator and Scientific Advisor Richard Hill published his detailed report on Carrington Rotations CR2166 thru CR2168.  The report was published in the 2016 Spring version of the JAPLO and can now also be accessed on ALPOSS’ Solar Observations & Reports page, or by clicking on the following picture:



March 3, 2016

Carrington Rotation 2173, a short summary

Carrington Rotation CR2173 ran from 2016/01/21 19:58 UT until 2016-02-18 04:07.
The rotation started with a total Active Region Area size of 180 and a Wolf Number of 59. It ended with a total region size of 260 millionths, and a Wolf Number of 260. During the period, the Sun showed 17 Active Regions (AR2484 – AR2501). There were 5 days where the total Active Region Areas reached, or exceeded 500 millionths. The rotation maxed out for the total region areas on February 9th, when the daily region area jumped from 460 to 650 millionths and the next day back to 350, mainly because of activity in AR2497. However, AR2497 also managed to produce the largest solar flare of the rotation on February 13th, an M1.8.
A smaller peak in total area of 540 millionths was noticed earlier on January 29th, when the largest sunspot of the rotation, AR2489, covered 300 millionths and registered a Dko on the McIntosh scale. The daily Wolf number reached its very pronounced maximum on February 6th at 113, which was the only day in the rotation where the Wolf number was above 100, but the spot area was only 400. The observations/images below, which were made on some of the key dates, were submitted by Monty Leventhal, Mike Borman and Theo Ramakers.

As of this writing, ALPO received 155 observations/images for the rotation, and we like to thank all that took the time to submit their images/observations.
The ALPO Team.

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