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.

Do Dark Matter and Dark Energy Exist?

Numerous searches for the particle or particles responsible for dark matter have so far come up empty.  What if dark matter doesn’t really exist?  Could there be alternative explanation for the phenomena attributed to dark matter?

In the November 10, 2017 issue of the Astrophysical Journal, Swiss astronomer André Maeder presents an intriguing hypothesis that non-baryonic dark matter need not exist, nor dark energy either.  In “Dynamical Effects of the Scale Invariance of the Empty Space: The Fall of Dark Matter?” he suggests that scale invariance of empty space (i.e. very low density) over time could be causing the phenomena we attribute to dark matter and dark energy.

What is scale invariance?  In the cosmological context, it means that empty space and its properties do not change following an expansion or contraction.  Scales of length, time, mass, energy, and so on are defined by the presence of matter.  In the presence of matter, space is not scale invariant.  But take the matter away, and empty space may have some non-intuitive properties.  The expanding universe may require adding a small acceleration term that opposes the force of gravity.  In the earlier denser universe, this acceleration term was tiny in comparison to the rate at which the expansion was slowing down, but in the later emptier universe, the acceleration term dominates.  Sound like dark energy, doesn’t it?  But maybe it is an inherent property of empty space itself.

The existence of dark matter is primarily suggested by two  observed dynamical anomalies:

  1. Flat outer rotation curve of spiral galaxies (including the Milky Way)
  2. Motions of galaxies within galaxy clusters

Many spiral galaxies have a well-known property that  beyond a certain distance from their centers, their rotation rate (the orbital velocity of stars at that distance) stays nearly constant rather than decreasing as one would expect from Keplerian motion / Newtonian dynamics (think planets orbiting the Sun in our own solar system— the farther the planet is from the Sun, the slower it orbits).  Only there seems to be evidence that the rotation curves of galaxies when they are young (as seen in the high-redshift universe) do have a Keplerian gradient, but in the present-day universe the rotation curve is flat.  So, it appears, flat rotation curves could be an age effect.  In other words, in the outer regions of spiral galaxies, stars may be orbiting at the same velocity as they did in the past when they were closer to the galactic center.  Maeder writes:

…the relatively flat rotation curves of spiral galaxies is an age effect from the mechanical laws, which account for the scale invariant properties of the empty space at large scales.  These laws predict that the circular velocities remain the same, while a very low expansion rate not far from the Hubble rate progressively extends the outer layers, increasing the radius of the Galaxy and decreasing its surface density like 1/t.

We need to study the rotation curves (as a function of galactocentric radius all the way out to the outermost reaches of the galaxy) of many more galaxies at different redshifts (and thus ages) to help us test the validity of the scale invariant vs. dark matter hypotheses.  Maeder suggests a thorough rotation study of two massive and fast-rotating galaxies, UGC 2953 (a.k.a. IC 356; 50-68 Mly) and UGC 2487 (a.k.a. NGC 1167; 219-225 Mly), would be quite interesting.

The observed motions of galaxies within many galaxy clusters seems to indicate there is a substantial amount of unseen mass within these clusters, through application of the virial theorem.  However, the motions within some galaxy clusters such as Coma (336 Mly) and Abell 2029 (1.1 Gly) may be explainable without the need to resort to “exotic” dark matter.

Then there’s the AVR (Age-Velocity Dispersion Relation) problem which, incidentally, has nothing to do with dark matter.  But it may offer evidence for the scale invariant hypothesis.  It is convenient to specify the motion of a star in a spiral galaxy such as the Milky Way in a galactocentric coordinate system.

U = component of velocity towards the galaxy center

V = component of velocity in the direction of galactic rotation

W = component of velocity orthogonal to the galactic plane

Maeder writes:

The AVR problem is that of explaining why the velocity dispersion, in particular for the W-component, considerably increases with the age of the stars considered … Continuous processes, such as spiral waves, collisions with giant molecular clouds, etc… are active in the disk plane and may effectively influence the stellar velocity distributions.  However…vertical heating (the increase of the dispersion σW) is unexpected, since the stars spend most of their lifetime out of the galactic plane.

There may be more to “empty” space than meets the eye…

References
Maeder, A., 2017, ApJ, 849, 158
arXiv:1710.11425

Theory and Observation

We continue our series of excerpts (and discussion) from the outstanding survey paper by George F. R. Ellis, Issues in the Philosophy of Cosmology.

Thesis F1: Philosophical choices necessarily underly cosmological theory.
Some cosmologists tend to ignore the philosophical choices underlying their theories; but simplistic or unexamined philosophical standpoints are still philosophical standpoints!

Cosmology, and indeed all human inquiry, is based on (at least) two unproven (though certainly reasonable) assumptions:

  1. The Universe exists.
  2. The human mind is at least to some degree capable of perceiving and understanding the Universe.

Any cosmological theory will have additional foundational unproven assumptions.  These are called axioms.  Ellis admonishes us to at least be aware of them, and to admit to them.

8.1 Criteria for theories
As regards criteria for a good scientific theory, typical would be the following four areas of assessment: (1) Satisfactory structure: (a) internal consistency, (b) simplicity (Ockham’s razor), and (c) aesthetic appeal (‘beauty’ or ‘elegance’); (2) Intrinsic explanatory power: (a) logical tightness, (b) scope of the theory—the ability to unify otherwise separate phenomena, and (c) probability of the theory or model with respect to some well-defined measure; (3) Extrinsic explanatory power, or relatedness: (a) connectedness to the rest of science, (b) extendability—providing a basis for further development; (4) Observational and experimental support, in terms of (a) testability: the ability to make quantitative as well as qualitative predications that can be tested; and (b) confirmation: the extent to which the theory is supported by such tests as have been made.

As you can see, a theory is not an opinion.  It must be well-supported by facts.  It must be internally consistent.  It must have explanatory power.  The Russian physicist A. I. Kitaĭgorodskiĭ (1914-1985) put it succinctly: “A first-rate theory predicts; a second-rate theory forbids, and a
third-rate theory explains after the event.”  Einstein’s special and general relativity are spectacular examples of first-rate theories.  In over 100 years of increasingly rigorous and sophisticated experiments and observations, relativity has never been proven to be incorrect.

Ellis emphasizes the importance of observational and experimental support in any scientific theory.

It is particularly the latter that characterizes a scientific theory, in contrast to other types of theories claiming to explain features of the universe and why things happen as they do.  It should be noted that these criteria are philosophical in nature in that they themselves cannot be proven to be correct by any experiment.  Rather their choice is based on past experience combined with philosophical reflection.  One could attempt to formulate criteria for good criteria for scientific theories, but of course these too would need to be philosophically justified.  The enterprise will end in infinite regress unless it is ended at some stage by a simple acceptance of a specific set of criteria.

So, even our criteria about what makes a good scientific theory rest upon axioms that cannot be proven.  But unlike religion, scientific theories never posit the existence of any supernatural entity.

Thesis F3: Conflicts will inevitably arise in applying criteria for satisfactory cosmological theories.
The thrust of much recent development has been away from observational tests toward strongly theoretically based proposals, indeed sometimes almost discounting observational tests.  At present this is being corrected by a healthy move to detailed observational analysis of the consequences of the proposed theories, marking a maturity of the subject.  However because of all the limitations in terms of observations and testing, in the cosmological context we still have to rely heavily on other criteria, and some criteria that are important in most of science may not really make sense.

String theory? Cosmic inflation?  Multiverse? If a theory is currently neither testable nor directly supported by observations, is it science, or something else?

References
Ellis, G. F. R. 2006, Issues in the Philosophy of Cosmology, Philosophy of Physics (Handbook of the Philosophy of Science), Ed. J. Butterfield and J. Earman (Elsevier, 2006), 1183-1285.
[http://arxiv.org/abs/astro-ph/0602280]

Symphonies by Women

How many women have achieved the compositional milestone of writing a symphony for full orchestra?  The answer is, quite a few!  What follows is what I believe to be a comprehensive list of all symphonies written by women.  If you know of others—or if you find anything here that needs correcting—please post a comment.  So many of these works have been unjustly neglected.  The day will come (hopefully soon) when any short list of the greatest composers will include women.

Looking towards the future, one composer to watch will certainly be Alma Deutscher.  Her first of many symphonies is eagerly anticipated!

Elfrida Andrée (1841-1929)
Symphony No. 1
Symphony No. 2

Lera Auerbach (1973-)
Symphony No. 1, “Chimera”
Symphony No. 2, “Requiem for a Poet”
Symphony No. 3, “The Infant Minstrel and His Peculiar Menagerie”

Elizabeth Austin (1938-)
Symphony No. 1, “Wilderness Symphony”
Symphony No. 2, “Lighthouse”

Grażyna Bacewicz (1909-1969)
Symphony No. 1
Symphony No. 2
Symphony No. 3
Symphony No. 4

Judith Bailey (1941-)
Symphony No. 1
Symphony No. 2

Elsa Barraine (1910-1999)
Symphony No. 1
Symphony No. 2

Amy Beach (1867-1944)
Gaelic Symphony

Sally Beamish (1956-)
Symphony No. 1
Symphony No. 2

Luise Adolpha Le Beau (1850-1927)
Symphony in F Major

Johanna Bordewijk-Roepman (1892-1971)
Symphony

Ina Boyle (1889-1967)
Symphony No. 1, “Glencree”
Symphony No. 2, “The Dream of the Rood”
Symphony No. 3, “From the Darkness”

Elisabetta Brusa (1954-)
Symphony No. 1
Symphony No. 2

Gloria Coates (1938-)
Symphony No. 1, “Music on Open Strings”
Symphony No. 2, “Music on Abstract Lines/ Illuminatio in Tenebris”
Symphony No. 3, “Symphony for Strings/Symphony Nocturne”
Symphony No. 4, “Chiaroscuro”
Symphony No. 5, “Drei mystische Gesänge”
Symphony No. 6, “Music in Microtones”
Symphony No. 7
Symphony No. 8, “Indian Sounds”
Symphony No. 9, “Homage to Van Gogh”
Symphony No. 10, “Drones of Druids on Celtic Ruins”
Symphony No. 11
Symphony No. 12
Symphony No. 13
Symphony No. 14, “The Americans”
Symphony No. 15, “Homage to Mozart”
Symphony No. 16, “Time Frozen”

Jean Coulthard (1908-2000)
Symphony No. 1
Symphony No. 2, “Choral Symphony, This Land
Symphony No. 3, “Lyric”
Symphony No. 4, “Autumn”

Nancy Dalberg (1881-1949)
Symphony in C minor

Yvonne Desportes (1907-1993)
Symphony No. 1, “Saint-Gindolph”
Symphony No. 2, “Monorythmie”
Symphony No. 3, “L’Éternel féminin”

Sophie Carmen Eckhardt-Gramatté (1899-1974)
Symphony No. 1
Symphony No. 2, “Manitoba”

Pozzi Escot (1933-)
Symphony No. 1
Symphony No. 2
Symphony No. 3
Symphony No. 4
Symphony No. 5
Symphony No. 6

Tsippi Fleischer (1946-)
Symphony No. 1, “Salt Crystals”
Symphony No. 2, “The Train”
Symphony No. 3, “Regarding Beauty”
Symphony No. 4, “A Passing Shadow”
Symphony No. 5, “Israeli-Jewish Collage”
Symphony No. 6, “The Eyes, Mirror of the Soul”
Symphony No. 7, “Choral Symphony”

Ilse Fromm-Michaels (1888-1986)
Symphony in C minor

Ruth Gipps (1921-1999)
Symphony No. 1
Symphony No. 2
Symphony No. 3
Symphony No. 4
Symphony No. 5

Julia Gomelskaya (1964-2016)
Symphony No. 1, “SymPhobia”
Symphony No. 2, “Ukraine Forever”
Symphony No. 3, “Magnet”
Symphony No. 4, “Ra-Aeternae”

Minna Keal (1909-1999)
Symphony, op. 3

Helvi Leiviskä (1902-1982)
Symphony No. 1
Symphony No. 2
Symphony No. 3

Ester Mägi (1922-)
Symphony

Nina Makarova (1908-1976)
Symphony in D minor

Emilie Mayer (1812-1883)
Symphony No. 1
Symphony No. 2
Symphony No. 3, “Military”
Symphony No. 4
Symphony No. 5
Symphony No. 6
Symphony No. 7
Symphony No. 8

Anne-Marie Ørbeck (1911-1996)
Symphony in D Major

Alla Pavlova (1952-)
Symphony No. 1 “Farewell, Russia” for chamber orchestra
Symphony No. 2 “For the New Millennium”
Symphony No. 3
Symphony No. 4
Symphony No. 5
Symphony No. 6
Symphony No. 7
Symphony No. 8
Symphony No. 9
Symphony No. 10

Dora Pejačević (1885-1923)
Symphony in F-sharp minor

Victoria Polevá (1962-)
Symphony No. 1
Symphony No. 2, “Offertory to Anton Bruckner”
Symphony No. 3, “White interment”

Florence Price (1887-1953)
Symphony No. 1
Symphony No. 2
Symphony No. 3
Symphony No. 4

Shulamit Ran (1949-)
Symphony

Johanna Senfter (1879-1961)
Symphony No. 1
Symphony No. 2
Symphony No. 3
Symphony No. 4
Symphony No. 5
Symphony No. 6
Symphony No. 7
Symphony No. 8
Symphony No. 9

Verdina Shlonsky (1905-1990)
Symphony

Alice Mary Smith (1839-1884)
Symphony No. 1 in C minor
Symphony No. 2 in A minor

Galina Ustvolskaya (1919-2006)
Symphony No. 1
Symphony No. 2, “True and Eternal Bliss!”
Symphony No. 3, “Jesus Messiah, Save Us!”
Symphony No. 4, “Prayer”
Symphony No. 5, “Amen”

Lucy Wilkins (1939-)
Symphony

Grace Williams (1906-1977)
Symphony No. 1, “Symphonic Impressions”
Symphony No. 2

Judith Lang Zaimont (1945-)
Symphony No. 1
Symphony No. 2, “Remember Me”
Symphony No. 3
Symphony No. 4 “Pure, Cool (Water)”

Ellen Taaffe Zwilich (1939-)
Symphony No. 1, “Three Movements for Orchestra”
Symphony No. 2 “Cello Symphony”
Symphony No. 3
Symphony No. 4, “The Gardens”
Symphony No. 5, “Concerto for Orchestra”

Average Orbital Distance

If a planet is orbiting the Sun with a semi-major axis, a, and orbital eccentricity, e, it is often stated that the average distance of the planet from the Sun is simply a.  This is only true for circular orbits (e = 0) where the planet maintains a constant distance from the Sun, and that distance is a.

Let’s imagine a hypothetical planet much like the Earth that has a perfectly circular orbit around the Sun with a = 1.0 AU and e = 0.  It is easy to see in this case that at all times, the planet will be exactly 1.0 AU from the Sun.

If, however, the planet orbits the Sun in an elliptical orbit at a = 1 AU and e > 0, we find that the planet orbits more slowly when it is farther from Sun than when it is nearer the Sun.  So, you’d expect to see the time-averaged average distance to be greater than 1.0 AU.  This is indeed the case.

The Earth’s current osculating orbital elements give us:

a = 0.999998 and e = 0.016694

Earth’s average distance from the Sun is thus:

Mercury, the innermost planet, has the most eccentric orbit of all the major planets:

a = 0.387098 and e = 0.205638

Mercury’s average distance from the Sun is thus:

Why are the Pleiades called the Seven Sisters?

The famous and beautiful Pleiades star cluster, which lies between 429 and 448 light years from us in the constellation Taurus the Bull, contains at least 2,109 stars that were formed around 125 million years ago—relatively recently on an astronomical timescale.  But when you look at the Pleiades with the unaided eye, unless you have unusually good vision and excellent sky conditions, you’ll see only six Pleiads.  If you see more than that, you’ll probably be able to see 8 or 9 Pleiads, maybe more.  But not seven.  So, why are the Pleiades called the Seven Sisters?

Here’s my conjecture.  Take a look at the Pleiades on a dark, moonless night. What do you see?  I think you’ll see a group of stars forming a tiny dipper shape, reminiscent of the much larger Little Dipper.

How many stars make up the Little Dipper shape?  Seven.  How many stars make up the Big Dipper shape?  Seven.  How many bright stars does nearby Orion have?  Seven.  Given this, and the fact that seven has long been considered a mystical number, it comes as no surprise, perhaps, that the Pleiades are called the Seven Sisters and not the Six Sisters or the Eight Sisters.  How many do you see?

The Pleiades will culminate1 at midnight for SW Wisconsinites on Friday night / Saturday morning, November 17/18.

1cross the celestial meridian; reach their highest point in the sky, due south

References
Bouy H., et al., 2015, A&A, 577, A148
Galli P. A. B., Moraux E., Bouy H., Bouvier J., et al., 2017, A&A, 598, A48
Stauffer J. R., Schultz G., Kirkpatrick J. D., 1998, ApJ, 499, L19

Saturn V

Today we celebrate the 50th anniversary of the inaugural flight of Wernher von Braun’s magnum opus, the giant Saturn V moon rocket.  This first flight was an unmanned mission, Apollo 4, and took place less than 10 months after the tragic launch pad fire that killed astronauts Gus Grissom, 40, Ed White, 36, and Roger Chaffee, 31.

Apollo 4 launch, November 9, 1967
Apollo 4 image of Earth at an altitude of 7,300 miles

The unmanned Apollo 4 mission was a complete success, paving the way for astronauts to go to the Moon.  After another successful unmanned test flight (Apollo 6), the Saturn V rocket carried the first astronauts into space on the Apollo 8 mission in December 1968.  On that mission, astronauts Frank Borman, Jim Lovell, and Bill Anders orbited the Moon for 20 hours and then returned safely to Earth.

Bill Anders took this iconic photo of Earth from Apollo 8 while in orbit around the Moon

“As of 2017, the Saturn V remains the tallest, heaviest, and most powerful (highest total impulse) rocket ever brought to operational status, and holds records for the heaviest payload launched and largest payload capacity to low Earth orbit (LEO) of 140,000 kg (310,000 lb), which included the third stage and unburned propellant needed to send the Apollo Command/Service Module and Lunar Module to the Moon.  To date, the Saturn V remains the only launch vehicle to launch missions to carry humans beyond low Earth orbit.”

Reference (for quoted material above)
Wikipedia contributors, “Saturn V,” Wikipedia, The Free Encyclopedia, https://en.wikipedia.org/w/index.php?title=Saturn_V&oldid=808028027 (accessed November 9, 2017).

Greater Intelligence

Allen Telescope Array; Photo Credit: Seth Shostak, SETI Institute, 2006
Calvin and Hobbes, November 8, 1989, by Bill Watterson

Could we please replace our idiocracy with a meritocracy?  Before it’s too late?  With checks and balances, of course.  Let’s raise the bar across our society instead of continuing to appeal to the lowest common denominator.  Our very survival depends upon it.

LED Residential Streetlight Debut in Dodgeville: Too Bright!

A new bright white LED streetlight made its debut in Dodgeville, Wisconsin on Friday, November 3, 2017, and it isn’t pretty.

The white-light LED streetlight is located at the NE corner of W. Washington St. & N. Johnson St. in Dodgeville.  The illumination level on the ground peaks at 3.15 fc.  An existing orange-light high pressure sodium streetlight at the SW corner of W. Division St. & N. Virginia Terrace peaks at 1.23 fc, which is typical.

Even though the reduction of uplight and near-horizontal light (i.e. “glare”) from this luminaire is a welcome improvement, an illumination level 2.6 times as bright as before is neither welcome nor justified.  Furthermore, lower illumination levels may be acceptable when using white-light LED luminaires in comparison with high pressure sodium (Glamox n.d.).  More research is needed on the effect of spectral composition on both brightness perception and, more importantly, visual acuity at various illuminance levels.

I do not have an instrument to measure the correlated color temperature (CCT) of this luminaire, but visually it looks to me to be around 4000 K, which is too blue.  I will check with the City of Dodgeville and report back here.  The International Dark-Sky Assocation (IDA n.d.) and the American Medical Assocation (AMA 2016) recommend using “warm white” LEDs with a CCT no higher than 3000 K, with 2700 K preferred.

References
AMA (2016), Human and Environmental Effects of Light Emitting Diode (LED) Community Lighting H-135.927.  Retrieved November 5, 2017 from https://policysearch.ama-assn.org/policyfinder/detail/H-135.927?uri=%2FAMADoc%2FHOD-135.927.xml.

Glamox (n.d.), The Glamox Brightness Sensitivity Test. Retrieved November 5, 2017 from http://glamox.com/gmo-recreational/led-brightness.

IDA (n.d.), LED: Why 3000K or Less.  Retrieved November 5, 2017 from http://www.darksky.org/lighting/3k/.

Oesper, D. (January 9, 2017), Avoid Blue-Rich LED Lighting.  http://cosmicreflections.skythisweek.info/2017/01/09/avoid-blue-rich-led-lighting/.

Changing Solar Distance

Between January 2 and 5 each year, the Earth reaches orbital perihelion, its closest distance to the Sun (0.983 AU).  Between July 3 and 6 each year, the Earth reaches orbital aphelion, its farthest distance from the Sun (1.017 AU).  These dates of perihelion and aphelion slowly shift across the calendar (always a half year apart) with a period between 22,000 and 26,000 years.

These distances can be easily derived knowing the semi-major axis (a) and orbital eccentricity (e) of the Earth’s orbit around the Sun, which are 1.000 and 0.017, respectively.

perihelion
q = a (1-e) = 1.000 (1-0.017) = 0.983 AU

aphelion
Q = a (1+e) = 1.000 (1+0.017) = 1.017 AU

So, the Earth is 0.034 AU closer to the Sun in early January than it is in early July.  This is about 5 million km or 3.1 million miles.

How great a distance is this, really?  The Moon in its orbit around the Earth is closer to the Sun around New Moon than it is around Full Moon.  Currently, this difference in distance ranges between 130,592 miles (April 2018) and 923,177 miles (October 2018).  Using the latter value, we see that the Moon’s maximum monthly range in distance from the Sun is 30% of the Earth’s range in distance from the Sun between perihelion and aphelion.

How about in terms of the diameter of the Sun?  The Sun’s diameter is 864,526 miles.  The Earth is just 3.6 Sun diameters closer to the Sun at perihelion than it is at aphelion.  Not much!  On average, the Earth is about 108 solar diameters distant from the Sun.

How about in terms of angular size?  When the Earth is at perihelion, the Sun exhibits an angular size of 29.7 arcminutes.  At aphelion, that angle is 28.7 arcminutes.

Can you see the difference?