Wallpaper Wednesday: SDO and Sunspots

16 07 2014
"Sweeping Arches and Loops", solar magnetic activity viewed in the ultraviolet, June 30, 2014.

“Sweeping Arches and Loops”, solar magnetic activity viewed in the ultraviolet, June 30, 2014.

Looking at some of the photos returned by NASA’s Solar Dynamics Observatory (SDO), you’d think contemporary solar observing had little in common with what was being done at Kodaikanal c. 1900-1910. But in addition to the dramatic images of solar loops like the one shown above, SDO also sends back sunspot records that closely resemble the photos and charts produced by C. Michie Smith, John Evershed, and company.

"Spots Galore," July 8, 2014. Image credit: Solar Dynamics Observatory/NASA

“Spots Galore,” July 8, 2014. Image credit: Solar Dynamics Observatory/NASA

According to SDO/NASA:

“The Sun sported a whole slew of substantial sunspots over the past 11 days (July 1-10, 2014). This movie and still show the Sun in filtered white light speckled with more and larger sunspots than we have seen in quite some time. Sunspots are darker, cooler regions on the Sun created by intense magnetic fields poking through the surface. The Sun may have passed its peak level of activity, but it will still be producing many more sunspots and solar storms during the rest of this solar cycle. The still image was taken on July 8 at 22:24 UT.”

Looks familiar!

Visit the NASA/SDO gallery to see more images of solar activity. Like the two above images, most are stills excerpted from videos. Click through each image to reach the links to .mov and .mp4 files.





Sunspots, 1903

14 07 2014
paper disc with handwritten notations of sunspots

Sunspot observation record, April 30-May 1, 1903. Image courtesy of Indian Institute of Astrophysics/JR

I was fortunate enough to spend some time studying the historic instruments and library collection at Kodaikanal Observatory in Tamil Nadu this past week. Run by the Indian Institute of Astrophysics, the observatory was founded in 1899 to facilitate solar observing. In 1907, John Evershed arrived on the scene to (quite famously) bring his “auto-collimating spectroheliograph” online. You can imagine my excitement when Mr. Selvendran, Senior In-Charge at KO, opened the door to the spectroheliograph room and slid open the shed roof to expose the instrument’s mirror. So cool.

But I’m getting ahead of myself. I spent my first day poking around KO’s fascinating library. Journals, books, catalogues, and ephemera stacked literally from floor to ceiling. So much stuff that I scarcely knew where to begin. But when I saw a stack of paper circles tucked into a corner shelf, I knew how I would spend the afternoon. I had only just read about these circles in one of C. Michie Smith’s (KO’s first director) annual reports.

Excerpt from Kodaikanal and Madras Observatories report for the year 1904.

Excerpt from Kodaikanal and Madras Observatories report for the year 1904.

Each of these 8-inch paper discs contains a record of 3-7 days of sunspot observations. Each spot was marked in pencil and assigned a letter (A, B, etc.). Every day, the observer recorded the new position and appearance of the lettered spots as they traversed the solar “surface”, i.e., the photosphere. For instance, in the following plates, sunspots A and B are shown moving from NNE to W between March 18 and 29, 1903.

Sunspot Observations, March 18-29, 1903. Image courtesy Indian Institute of Astrophysics.

Sunspot Observations, March 18-29, 1903. Image courtesy Indian Institute of Astrophysics/JR.

Sunspot Observations, March 18-29, 1903, detail. Image courtesy Indian Institute of Astrophysics.

Sunspot Observations, March 18-29, 1903, detail. Image courtesy Indian Institute of Astrophysics/JR.

The next image shows that those same spots continued westward between March 30 and April 2, 1903, breaking up as they went. You can also see a second line of spots traveling roughly parallel to the solar equator. They started out as indistinct patches at the eastern edge of the disc on the March 27-28. The March 30-April 2 disc shows how long it took for them to move half way across the Sun.

XXXX.

Sunspot Observations, March 30-April 2, 1903. Image courtesy Indian Institute of Astrophysics/JR.

According to C. Michie Smith, observers hand-recorded sunspots on 343 out of 365 days in 1904. What dedication, and this at a time when they didn’t really know what sunspots were. Observers just put in the hours and trusted that their efforts would one day lead to enlightenment.





India Calling

30 05 2014
John Evershed and Assistant, Kodaikanal Solar Observatory. Image courtesy IIA Archives.

John Evershed and Assistant, Kodaikanal Solar Observatory. Image courtesy IIA Archives.

I took my first dose of live typhoid vaccine this morning, so I guess it’s official: I’m on my way back to India for the summer. One of the benefits of the ACLS NFF is the research budget—large enough to cover the cost of two conferences and a trip to India in the same academic year. So, in two weeks, I’ll be rolling into the library at the Indian Institute of Astrophysics in Bangalore to complete “step two” of a new research project. Last summer was “step one,” exploratory research in the Lick Observatory archives at UC-Santa Cruz. No idea what “step three” will look like!

This project is still in its infancy, but I’m looking at the ways in which “new astronomy” (i.e., spectroscopy) affected observatory design at the end of the nineteenth century. More specifically, I’m trying to track the intellectual shift of Indian astronomers away from the UK and toward the US in the era of solar astronomy. It seems that even though Kodaikanal Observatory was constructed in the (British) colonial era, the astronomers were working more closely with Mt Wilson and Lick Observatories than with their British counterparts. Maybe. Possibly. That’s the great thing about research questions: even if I come back with “wrong answer,” I’ll have learned something new.





Looks like a duck, sounds like a duck…

18 06 2013

I was adding records to my bibliographic database this afternoon when I stumbled across this interesting tidbit in the Proceedings of the Delhi Archaeological Society:

7th March, 1850

A letter from Captain Dewar, of 1st Cavalry, was read, reporting the discovery of a large stone in the Jhansi district, which, when struck, emitted a sound equal to that of the finest gong.

The Secretary was requested to write to Captain Dewar, to ascertain from that gentleman, what he thought the probable expense of the removal of this stone to Delhi might be.

The finest gong? Sounds like a meteorite to me, but which one?

As far as I can tell, there were only 7 meteorite falls (observed falls) on the South Asian subcontinent before 1850. Four of those were L chondrite, two were H type, one was a diogenite. Those two H types could have had enough iron mixed with stone to make a bell-like sound if struck, but the mass of those falls have been located and removed to London (Akbarpur, fall 18 April 1838, found in Uttar Pradesh; Charwallas, 12 June 1834, found in Haryana). So, if Dewar was hitting a meteorite with his hammer, it must have been from an unobserved (or at least unrecorded) fall.

In a list of 106 meteorites known to have fallen in India (both observed/unobserved falls) before 1926, only four of those were proper irons (GarhiYasin, Kodaikanal, Nedagolla, Samelia). Based on date of observed fall/discovery location, none of those could be the Jhansi meteorite. None of the remaining 102 meteorites on the list make good candidates, either.

Unfortunately, I could find no record of the stone being shipped to Delhi. The Proceedings seem to come to an end with the issue I have in my office (January 1953); I’ve lost the meteorite’s trail. It’s indeed a puzzle, the solution to which is probably buried deep in the Museum of Natural History with every other meteorite collected by the British during the colonial era.





Kodaikanal Observatory

2 03 2013
Kodaikanal Observatory

Kodaikanal Observatory, c. 1907

I think this photo demonstrates why I’ve lost interest in my current project and wish I could start working on a new one. The only caption I’ve seen attached to this image is “John and Mary Ackworth Evershed, Kodaikanal.” The Eversheds arrived at Kodaikanal Observatory in January 1907. John had (reluctantly) accepted the position as “European Assistant” to the observatory’s director, Michie Smith, arriving in India after a productive visit to the solar observatory on Mt Wilson. Not surprisingly, most of Evershed’s time at the observatory was spent installing and then using spectroheliographs to study the spectra of sunspots. He became the observatory’s director in 1911.

All very interesting, I’m sure, but what I want to know: how can this possibly be a photo of “John and Mary Ackworth Evershed” when it includes sixteen other people, fourteen of whom are obviously not “European Assistants”? Colonial astronomy drives me crazy, it really does.