Special show last week: the solar eclipse of Feb. 16! Yohkoh observed two of the three eclipse episodes this time - we get eclipse opportunities twice a year, with up to five episodes per eclipse because of the complicated relative motions of spacecraft, Sun, and Moon. See [1] [2] [3] [4] for earlier Yohkoh views of eclipses.   
In this particular image, you will notice the lunar shadow occulting the sharply pointed cusp that formed on the solar equator following a major flare and CME, the first time we've seen this behavior. See the science nugget below for more information about the remarkable behavior of these transequatorial magnetic structures - which, our graybeards say, can only form as a result of magnetic reconnection!

Transequatorial loops, the movie

Science Nugget: Feb 19, 1999

1. Hajime ni

Yohkoh began observing during the declining phase of the past solar cycle, and now it's observing the rise phase of the next. One of the most exciting differences in the nature of the data has been the behavior of the trans-equatorial loops, which appear to connect between independent active regions in the north and the south. The single best example from the past maximum was a remarkable quadrupolar feature described in a 1996 paper by S. Tsuneta, but in fact what we describe below looks quite different from that case.

The items below are just superficial comments on some characteristics of the loops, with no analysis. The movie is at the end.

2. Ost und West

At the time of writing, the NS structure had not quite arrived at the west limb. Nevertheless, the comparison of east and west apparitions is neat:
  The image at left shows the two limbs of the Sun at a spacing of about two weeks, to match the solar rotation from limb to limb. At the time of the east image (left), the transequatorial loops were already well-formed; our previous real-time glimpse two days earlier did not show them. The difference of the background levels in these images, incidentally, is due to imperfect image preparation in these quasi-real-time data reductions. 

3. Eruption Solaire

A remarkable solar flare occurred on February 16, leading to a major CME and geomagnetic storm. Yohkoh missed the flare itself, but the images below show that we recorded a remarkable post-flare, and post-CME, phenomenon. So far as we're aware such a thing has never before been observed in X-rays.
  These three images show the X-ray sun before the flare, after it, and later still. The remarkable feature is the large cusp-shaped structure pointing to the west (right). This strongly suggests post-CME magnetic reconnection; the timing implies that the flare caused the CME, opening the streamer field, which then reconnected in the classical picture. The very bright flare loops (central panel) presumably have some other explanation they are not the result of the closing-down of field lines opened in the eruption. 

4. El Cine

Well, in fact this remarkable structure did several other noteworthy things as it rotated across the disk, but I don't have time to display them. We really are seeing some developments ("restructurings") that should help us to understand the large-scale coronal magnetic field and its basic magnetohydrodynamics. Somebody should follow through, please, with analyses. Here is a two-week movie, but please note that it's got major gaps (see the GOES plot above) since we have only used the real-time data.

Click on the thumbnail to get the GIF version of the movie, but beware that it's 2.8 MB long. If you're in a bandwidth-challenged domain, the mpeg version - somewhat more detailed - only has 404 kB. The movie contains at least three other quite interesting morphological features: a homologous predecessor of the flare cusp; a ripple effect along the northern footpoints of the structure, and the 3D form of the lower boundary. Sorry there is no time to display them properly. See last week's nugget for links to other related nugget pages.

February 19, 1999: Hugh Hudson (email hudson@isass0.solar.isas.ac.jp; comments especially welcome from German, French, or Spanish solar physicists regarding my topic titles!)