Paul Martsching – Cosmic Reflections

Perseid Outburst of 14 Aug 2021

The Earth passed through an unexpected filament from Comet 109P/Swift-Tuttle, causing a spectacular enhancement of the Perseids on Saturday morning August 14 beginning around 0700 UT and continuing at least until 0945 UT when morning twilight began interfering with our observations. This is some 35 hours after the traditional peak (filament was at solar longitude ~141.5˚, whereas the traditional peak is at 140.0˚ – 140.1˚). Paul Martsching and I were observing NE of Ames, Iowa and saw single-observer observed rates of 40 to 60+ meteors per hour for an extended period. Many were bright (0th and 1st magnitude, some brighter). Paul’s peak hourly rate was 64 Perseids during the hour 0845 – 0945 UT.

Visual Observed Hourly Rates from Story County, Iowa (Data from Paul Martsching)

The dip in the meteor counts around 0830 looks to be real, and appears to be corroborated by the radio meteor counts from Germany (shown at the top of this article). This could be due to a dip in the brighter meteor rate (but not the fainter ones we couldn’t see), or perhaps it was a dip in the overall rate as the Earth passed through two “strands” of the meteoroid filament.

The IMO website reports the following:

“CBET 5016 (Jenniskens, 2021) states the peak was reached on Aug. 14, 08^h02^m UT (solar longitude 141.474 ± 0.005 degrees (equinox J2000.0)), with maximum ZHR between 130 ± 20 (calculated from CAMS Texas and California networks) and 210 ± 20 (calculated by K. Miskotte (DMS) from Pierre Martin’s visual observations) in good agreement with values calculated by H. Ogawa of the International Project for Radio Meteor Observation from radio forward scatter meteor observations. According to Peter Jenniskens (MeteorNews (b)), this probable filament may have been crossed over the last years, especially in 2018 (ZHR ~ 25 at solar longitude 140.95°) and 2019 (ZHR ~ 30 at solar longitude 141.02°) .”

Paul Martsching kept a detailed visual record of the outburst. He writes, “Apparently the ZHR was around double what we actually saw. The brightness index indicates a lot of faint meteors.”

15-minute-interval counts (Paul Martsching)

Paul writes, “The rate went up to ~ 60/hour for nearly an hour; then fell back to ~ 40/hour for 45 minutes; then went back up to ~75/hour for 45 minutes; then seemed to be declining as morning twilight was interfering.”

Paul’s detailed log sheets are shown at the end of this article.

Meteor outbursts like this are rare, but they do occur from time to time. In the future, it would be nice if some of the automated meteor camera systems around the world could do some real-time processing in order to immediately alert visual observers of any outburst in progress, similar to what has often been done for auroral displays

Paul uses a talking clock and a steno pad to record the details of the meteors he sees, observing conditions, etc., without taking his eyes off the sky or needing to use a flashlight. He rolls a rubber band down the page to act as a guide for the pencil.

I have used a digital tape recorder with an external microphone that can be turned on and off for each event, and a talking clock. Unfortunately, I lost all that equipment in the Houston Memorial Day Weekend flood in 2015.

I am looking for a digital voice recorder that records the time each activation of the external microphone occurs. In other words, when I later play back each meteor description audio “snippet”, I want to be able to know exactly what the time was when the audio was recorded, thus eliminating the need for a talking clock. Does any such device exist?

A number of automated meteor cameras captured this outburst, but nothing can compare with seeing it visually under excellent conditions! I hope many others saw this event, but I suspect most visual observers did not go out, since it was after the predicted peak nights of Aug 11/12 and 12/13. A nice surprise, and on a weekend, too!

Scintillating Stars But Not Planets

Aristotle (384 BC – 322 BC) may have been the first person to write that stars twinkle but planets don’t, though our understanding of twinkling has evolved since he explained that “The planets are near, so that the visual ray reaches them in its full vigour, but when it comes to the fixed stars it is quivering because of the distance and its excessive extension.”

John Stedman (1744-1797), a controversial and complicated figure to be sure, writes the following dialog between teacher and student in The Study of Astronomy, Adapted to the capacities of youth (1796):

PUPIL. How is the twinkling of the stars in a clear night accounted for?

TUTOR. It arises from the continual agitation of the air or atmosphere through which we view them; the particles of air being always in motion, will cause a twinkling in any distant luminous body, which shines with a strong light.

PUPIL. Then, I suppose, the planets not being luminous, is the reason why they do not twinkle.

TUTOR. Most certainly. The feeble light with which they shine is not sufficient to cause such an appearance.

Still not quite right, but closer to our current understanding. Our modern term for “twinkling” is atmospheric scintillation, which is changes in a star’s brightness caused by curved wavefronts focusing or defocusing starlight.

Scintillation is caused by refractive index variations (due to differences in pressure, temperature, and humidity) of “pockets” of air passing in front of the light path between star and observer at a typical height of about 5 miles. These pockets are typically about 3 inches across, so from the naked eye observer’s standpoint, they subtend an angle of about 2 arcseconds.

The largest angular diameters of stars are on the order of 50 milliarcseconds¹ (R Doradus, Betelgeuse, and Mira), and only seventeen stars have an an angular diameter larger than 1 milliarcsecond. So, it is easy to see how cells of air on the order of 2 arcseconds across moving across the light path could cause the stars to flicker and flash as seen with the unaided eye.

The five planets that are easily visible to the unaided eye (Mercury, Venus, Mars, Jupiter, and Saturn) have angular diameters that range from 3.5 arcseconds (Mars, at its most distant) up to 66 arcseconds (Venus, at its closest). Since the disk of a planet subtends multiple air cells, the different refractive indexes tend to cancel each other out, and the planet shines with a steady light.

From my own experience watching meteors many nights with my friend Paul Martsching, our reclining lawn chairs just a few feet apart, I have sometimes seen a principal star briefly brighten by two magnitudes or more, with Paul seeing no change in the star’s brightness, and vice versa.

Stedman’s dialogue next turns to the distances to the nearest stars.

PUPIL. Have the stars then light in themselves?

TUTOR. They undoubtedly shine with their own native light, or we should not see even the nearest of them: the distance being so immensely great, that if a cannon-ball were to travel from it to the sun, with the same velocity with which it left the cannon, it would be more than 1 million, 868 thousand years, before it reached it.

He adds a footnote:

The distance of Syrius is 18,717,442,690,526 miles. A cannon-ball going at the rate of 1143 miles an hour, would only reach the sun in about 1,868,307 years, 88 days.

Where Stedman comes up with the velocity of a cannon-ball is unclear, but the Earth’s rotational speed at the equator is 1,040 mph, close to Stedman’s cannon-ball velocity of 1,143 mph. He states the distance to the brightest star Sirius—probably then thought to be the nearest star—is 18,717,442,690,526 miles or 3.18 light years, a bit short of the actual value of 8.60 light years. The first measurements of stellar parallax lie 42 years in the future when Stedman’s book was published.

¹ 1 milliarcsecond (1 mas) = 0.001 arcsecond

References
Aristotle, De Caelo, Book 2, chap.8, par. 290a, 18
Crumey, A., 2014, MNRAS, 442, 2600
Dravins, D., Lindegren, L., Mezey, E., Young, A. T., 1997a, PASP, 109, 173
Ellison, M. A., & Seddon, H., 1952, MNRAS, 112, 73
Stedman, J., 1796, The Study of Astronomy, Adapted to the capacities of youth

June Boötids

Some meteor showers give a more-or-less reliable performance the same time each year, but others have an occasional year with (sometimes substantial) activity punctuating many years with little or no activity. The June Boötids, which may or may not be visible any night this week but most likely Wednesday morning or Wednesday evening if at all, is one such shower. This year, however, any meteors that do occur will be compromised by the nearly-full moon.

One hallmark of the June Boötids is that they are unusually slow meteors, so they’re easy to identify if you see one. Look for the meteors to emanate from a region of the sky a few degrees north of the top of the “kite” of Boötes.

Of the 38 meteor showers listed in the IMO‘s “Working List of Visual Meteor Showers”, the lowest V_∞, which is the pre-atmospheric Earth-apparent meteor velocity, is 18 km/s. The three showers with that velocity are the π Puppids (Apr 23, δ=-45°), June Boötids (Jun 27, δ=+48°), and Phoenicids (Dec 2, δ=-53°). For those of us living in the northern U.S., the June Boötids is the only one of these three showers we are ever likely to see.

Outbursts of June Boötids activity approaching or even exceeding 100 meteors per hour (single observer hourly rate) occurred in 1916, 1921, 1927, 1998, and 2004. When the next outburst will occur none can yet say.

In eight years between 2001 and 2014 inclusive, my friend and expert visual meteor observer Paul Martsching of Ames, Iowa observed fourteen 0-magnitude or brighter June Boötids, the brightest of which was -4 in 2004. He has seen June Boötids activity as early as June 22nd and as late as July 1st. Of the 44 June Boötids he has observed, 52% were white in color, 27% yellow, and 21% orange.

Though we’re always at the mercy of the weather and the Moon and a workaday world that does little to accommodate the observational astronomy amateur scientist, meteor watching is a rewarding activity. Even when meteor activity is sparse, you have time to think, to study the sky, to experience the beauty of the night.

Obsolete But Still Relevant

Under the direction of Friedrich Argelander (1799-1875), astronomers at the Bonn Observatory spent seven years (1852 to 1859) measuring the positions and magnitudes of roughly 324,000 stars, one star at a time. This phenomenal work resulted in the Bonner Durchmusterung (BD) catalog and atlas, which included stars down to approximately magnitude 9.5 and is a tribute to the foresight of Argelander and the diligence of his small staff. The Bonner Durchmusterung was the last star catalog to be produced without the benefit of photography, and it is certainly the most comprehensive of the pre-photographic atlases.

Back in 2007, Alan MacRobert stated (Sky & Telescope, July 2007, p. 59), “Someday machines will measure the brightness of every star in the sky to some amazingly deep magnitude many times a night, and blind software will compile and analyze light curves automatically.” No doubt, he is correct, but he does add that this has not happened yet, despite years of pregnant expectations.

But we are getting closer to that day, with the Large Synoptic Survey Telescope (LSST) scheduled to come online in 2022 and many other similar survey instruments in the pipeline or already operational. That is one reason as an amateur astronomer with limited resources (including time) I focus on observing the occultation of stars by asteroids and trans-Neptunian objects. It is one of the few areas where an amateur observational astronomer can provide location-dependent observations. You are either in the shadow path or you are not. Though truth be told I would rather be studying exoplanets, we can only do what we have the resources to do—regardless of talent or potential.

History is full of examples of skills and techniques made obsolete almost overnight by new technologies (or a different point of view), but what is seldom recorded is the sense of desolation and indeed mortality experienced by those unfortunate enough to live to see that their highly-developed skills are no longer wanted or needed. As my meteor-watching friend Paul Martsching has said, “It is good we don’t live forever: we are a product of our times.” He realizes full well that someday automated systems will count every meteor above the horizon far better and more completely than any visual meteor observer can, but for many years he has carefully recorded meteor activity many nights a year. The data he collects will always be relevant as part of the historical record, at least, and the sheer joy of being out under the stars and away from light pollution can never be replaced by a computer. To us, astronomy is something much deeper than what can be delivered through a computer screen.

We are a product of our times, and as we approach the twilight (or autumn) of our lives we don’t necessarily feel compelled to embrace every new thing that comes along. Peace.

From the standpoint of daily life, however, there is one thing we do know: that we are here for the sake of each other—above all for those upon whose smile and well-being our own happiness depends, and also for the countless unknown souls with whose fate we are connected by a bond of sympathy. Many times a day I realize how much my own outer and inner life is built upon the labors of my fellow men, both living and dead, and how earnestly I must exert myself in order to give in return as much as I have received. – Albert Einstein (1879-1955)

Meteor Watcher’s Network

I’ve been a meteor watching enthusiast since at least the early 1980s. I had the good fortune back then of getting to know Paul Martsching when we both lived in Ames, Iowa, and few people in the world have logged more hours in the name of meteor science than he. We have been close friends ever since.

We’ve learned that here in the U.S. Midwest, for any given astronomical event you wish to observe, there is between a 2/3 and 3/4 chance that it will be clouded out—unless you are willing to travel. Weather forecasting has gotten much better over the years, and nowadays you can vastly improve your chances of not missing that important astronomical event, such as the Perseid meteor shower in August or the Geminid meteor shower in December.

Paul and I have traveled from Ames, Iowa to Nebraska, South Dakota, North Dakota, Kansas, Missouri, and Illinois over the years to escape cloudy skies. Just last year, we had to travel to north of Jamestown, North Dakota to see the Perseids, and this year it appears we will need to travel to southern Kansas, Oklahoma, or Arkansas to get a clear view of the Geminids.

Weather forecasts don’t begin to get really accurate until about 48 hours out, so we often have to decide at nearly the last minute where to travel. Therein lies the problem. Where can we find a safe observing spot to put down our lawn chairs where there are no terrestrial lights visible brighter than the brightest stars, and no objectionable skyglow from sources or cities over the horizon? It is a tall challenge.

What we need to develop is a nationwide network of folks who know of good places to watch meteors. This would include astronomy clubs, individual astronomy enthusiasts, managers of parks and other natural areas, rural land owners who would allow meteor watchers on their land, rural B&Bs, cabins, lodges, ranches, and so on. Once you know where you need to go to get out from under the clouds, there would be someone you could call in that area of the country to make expeditious observing arrangements for that night or the following night. And perhaps lodging as well, if available.

If you would like to work with me to build a meteor watcher’s network or have ideas to share, please post comments here or contact me directly.

Total Solar Eclipse of August 21, 2017

Sunday morning our eclipse party was SE of Grand Island, Nebraska, but weather prospects were not good for Nebraska on eclipse Monday so we decided to make the long trek to Wyoming. Fortunately, my friends John & Nancy Wunderlin had invited us to their eclipse-watching site in Glendo State Park near Glendo, Wyoming. I brought along a Coronado 70 mm Hα telescope, a Meade 8-inch Schmidt-Cassegrain with a white-light full-aperture solar filter from Thousand Oaks Optical, and Fujinon 16 x 70 binoculars, also with Thousand Oaks solar filters, mounted on a heavy-duty Orion binocular mount. While John took pictures of the eclipse, I was busy showing a large group of eclipse watchers views of the partial eclipse before and after totality. During totality, we ignored those instruments and viewed the eclipse using our unaided eyes and unfiltered 7 x 50 binoculars.

Photograph by John Wunderlin, Glendo State Park, Wyoming, August 21, 2017

We had perfect conditions for this eclipse: a very clear sky, low humidity, and reasonably high elevation (~4,700 ft.). This total eclipse was for me more impressive than the only other total solar eclipse I’ve seen: February 26, 1979 near Riverton, Manitoba. It is difficult to describe in words or even photographs the beauty of this event! Definitely worth driving a rented Cruise America RV 2,200 miles and spending three nights in the RV—the night before and the night after the eclipse without hookups, the latter in the Wal Mart parking lot in Chadron, Nebraska. Besides its size, an RV is more challenging to drive than a car or minivan—especially if it is windy—and every time a semi passes you get buffeted. Both hands on the wheel! And then there was the 6+ hours we spent driving from Glendo State Park to Glendo and up WY 319 up to US 18/20—a distance of only about 20 miles—after the eclipse. Traffic was at a standstill most of that time and we really appreciated having the on-board restroom. Despite a huge number of people heading home after the eclipse, it was the most civilized group you could imagine under the circumstances. The kind of people who make the effort to put themselves into the path of totality are probably more intellectually curious and courteous than your average American. We were all still basking in the afterglow of totality, I’m sure.

There are so many aspects of the eclipse to describe, but I’ll focus on just a few here. First, I had the equipment all set up before first contact, which is the point at which the disc of the Moon first touches the disc of the Sun, and the partial eclipse begins. Likewise, none of the equipment came down until after last contact, when the Sun once again became completely uncovered. We watched the entire eclipse intently from beginning to end. Though I was busy tending to the two telescopes and binoculars and answering eclipse questions for the wonderful throng of kids and adults who joined us, I did have a chance from time to time to look up at the Sun with the eclipse glasses we all had and frequently used. Paul Martsching saw to it that no one went without their own pair of eclipse glasses.

The pre- and post-totality Sun offered up views of a surprising number of sunspots, some very small, and it was interesting to watch them being covered and later uncovered by the Moon. One of the irregular sunspot groups reminded me of a monkey looking backwards over its shoulder.

As totality began, it suddenly got darker, and we marveled at the handful of planets and stars we could see. Venus was especially bright. The prominences were a beautiful shade of red and very bright, even to the unaided eye, and in 7×50 binoculars the view was stunning! I have seen many photographs of totality, but no photograph can compare to the view you get with the unaided eye or through binoculars. You just have to be there to experience it first hand.

After totality was over and while the Sun was still mostly covered by the Moon, the solar prominences in the Coronado Hα telescope were incredibly bright, brilliantly red, larger and much easier to see than they ever are when viewing the uneclipsed Sun. Wow!

When the Sun was about a third to a half uncovered (unfortunately, I didn’t note the time because I was so busy tending to the instruments, listening to eclipse impressions, and answering questions), I noticed a very strange phenomenon in the Meade 8-inch telescope, where the filtered Sun was magnified enough to mostly fill the field of view. A round black bead—a little larger than the largest sunspot—moved along the southwest limb of the Sun from about the 7 o’clock to the 9 o’clock position relative to the cusps. At first glance, I thought it might be a bird or an airplane. The speed seemed about right for a bird, in front of the Sun between one and two seconds, but this black circle moved along the solar limb instead of transecting the Sun! Then, just a couple of seconds later, another black bead appeared, moved along the solar limb, and disappeared precisely as the first one had. That was it. I saw no more. Was this some sort of unusual atmospheric phenomenon? Whatever it was, it definitely wasn’t floaters.

As Shakespeare wrote around the turn of the 17th century, there are more things in heaven and earth than are dreamt of in our philosophy. A total solar eclipse certainly confirms that notion.

Lyrid Meteor Shower

The Lyrid meteor shower peaks this Friday night and Saturday morning, April 21/22, and this year we have the perfect trifecta: a weekend event, a peak favorable for North America, and little to no moon interference. Now, all we need is clear skies!

The Lyrids are expected to crescendo to a peak somewhere between 11 p.m. Friday evening and 10 a.m. Saturday morning. One prediction I found even has them peaking at noon on Saturday.

Lyrids – April 21/22 – Local Circumstances for Dodgeville, WI

When to watch? At a minimum, I’d recommend observing at least two hours, from 2:30 to 4:30 a.m. You can expect to see maybe 15 fairly fast meteors per hour.

My friend Paul Martsching of Ames, Iowa has been one of the most active and meticulous meteor observers in the world. In nearly 30 years of observing this shower, he notes that 21% of Lyrid meteors leave persistent trains. Though few Lyrids reach fireball status, Paul did observe a -8 Lyrid at 1:50 a.m. on April 22, 2014 (his brightest Lyrid ever) that left a train that lasted five and a half minutes! Paul notes a color distribution of the Lyrid meteors as 73% white, 22% yellow, and 5% orange.

I’m still trying to find a good location within about 10 miles of Dodgeville to watch meteor showers. Governor Dodge State Park would be ideal, but anyone who isn’t camping has to leave the park by 11:00 p.m.

Meteor watching is most enjoyable in groups of two or more. I’m planning to observe this shower, so contact me if you’d like to team up!

Two Places, Same Meteor?

A good friend of mine, Paul Martsching, records meteor activity many nights a year for the American Meteor Society near Ames, Iowa, and has been doing so for many years. On some of those nights, I am also recording meteor activity near Dodgeville, Wisconsin. Is it possible for both of us to see the same meteor?

Paul’s observing location near Ames and my observing location near Dodgeville are separated by 180 miles. Meteors burn up in the atmosphere at an altitude of about 50 miles. Using a little simple trigonometry, we can find that the parallax angle between where Paul and I see the meteor is about 122°. So, a meteor at either of our zeniths would be below the horizon at the other location. If, on the other hand, Paul saw a bright meteor 29° above his NE horizon, I might be able to see the same meteor 29° above my SW horizon.

In general, if two observers are separated by a distance d in miles, then they will see the location of the meteor in the sky shifted by approximately s°, as given in the following equation:

This equation assumes that the curvature of the Earth is negligible, a reasonable assumption only when the two observers are relatively close to one another.

A more generalizable equation, taking into account the curvature of the Earth, though still assuming a spherical Earth is:

Plugging in the numbers, we get

We essentially get the same answer—a parallax angle of 122°. In fact, using the small angle approximation tan x ≅ x for x << 1 (where tan x is in radians), the equation above simplifies to

If this looks a little familiar, it is. Assuming the meteor burns up at an altitude of 50 miles, the equation immediately above becomes

which is our original equation! So, for distances on the order of 200 miles or so (or less) we can completely ignore the curvature of the Earth.