Sunday, December 10, 2017

Creator of the Stars of Night

A gift to all, this Advent Season:

(Start at one minute in, to avoid the intro.)

In the midst of debates over which telescope is the "best", or exactly how the eye perceives objects through the eyepiece, it's all too easy to lose sight of the fact that...


And if Latin's not your thing, here's the same song in English:

Saturday, December 2, 2017

Explorers! (part 2)

There are so many adjectives appropriate to describing deep sky objects: beautiful, awe-inspiring, spectacular - just to name a few. But one word you will not often find on that list would be dramatic. For something to be dramatic, there has to be something actually going on. And for the most part, what we see beyond the confines of our Solar System has all the trappings of eternity. Other than the occasional supernova, nothing happens that is discernable to the human eye - at least, nothing notable over the lifespan of any single individual. With rare exception, what you observe tonight looks pretty much the same as it did 500 years ago, and will remain unchanged for the next 500. And that's actually part of its charm. There's a comfort in the Unchanging Heavens, in their timelessness, in knowing that the ancient Babylonians were observing the same sights as ourselves, as will be our unknowable descendants.

Not so with the Moon. Oh, I know, "Nothing ever happens on the Moon" (Robert A. Heinlein). It looks the same now as it did millions of years ago. The footprints of American astronauts will still be there ages after the very name of America has been long forgotten. Yes, in that sense, nothing does happen on the Moon. But in another sense, it is forever constantly changing - day by day, hour by hour, minute by minute. I am referring to its appearance to an Earthbound observer. The relentless, inexorable movement of the terminator from east to west with its attendant shadows creates a landscape of ever shifting contour. That lonely mountain with its truly spectacular miles-long isosceles triangle of a shadow will soften to a hard-to-detect whitish smudge over the course of an evening. A line of isolated points of light will emerge as the colossal rim of a crater while you watch. That deep well of purest black on a crater floor will be brilliantly illuminated before you know it. The wrinkled and convoluted floor of a Mare will appear smooth as glass in a matter of hours. And all of these mutations are visible with the most modest of equipment - no "light bucket" required.

And sometimes transience can be as appealing as permanence. I love knowing the Big Dipper will be there for my grandchildren, and for their grandchildren. But I also find joy in a sunset that will disappear forever in 15 minutes - and find it for that very reason. With the Moon, you can have it both ways. For just this once, you can both have your cake and eat it too. The Moon's features may be eternal, but your view of them is all too fleeting. And to the cognoscenti, there's pleasure in knowing that it's not simply a matter of waiting until next month to see the same pageant of shifting shadows across any given feature. Due to the librations and the eccentricity of the lunar orbit, the same pattern of shadows you see tonight will not recur for another 18 years. (At my age, that basically means that I am always seeing something on the Moon for the Last Time. So you can bet that I pay attention.)

And thus this posting's title - Explorers! I grew up in Arizona, and have fond memories of driving through what was back then in the 1960s an endless wilderness (sadly gone today, all "developed"), seeing at every turn of the road a new horizon, a new distant range of mountains, a canyon or a river valley. That's how I feel today observing the Moon. The advancing line of sunlight is forever opening up new vistas, or at least a new way of looking at old ones. The manner in which that unnamed feature west of Kunowsky Crater revealed itself will not be repeated until 2035! And I was fortunate enough to have seen it... and wonder.

Thursday, November 30, 2017


Last Tuesday evening at an Alpha Ridge impromptu, I decided to make it an exclusively Moon night, and not look at anything else.* Despite my reputation as a Lunatic, I hadn't done that a long time, and it felt good to get Back to Basics as regards lunar observing. I started out, as always, by putting in a relatively low power, 13mm Nagler eyepiece and taking in the Moon as a whole. Then I upped the magnification, moving to a 4.5mm Delos and cruising up and down the length of the terminator, looking for anything particularly eye catching.

Well, what really caught my eye was an intriguing line of three piercingly bright dots off to the right (in my mirror-imaged view) of the day/night line. They were almost starlike in their intensity and pointlike appearance, looking for all the world like a row of streetlights on a dark road. (See above image. The three dots just to the left of center were in  splendid isolation when I first caught sight of them.) I decided to stick with them and see what they would become (a mountain range? the wall of a crater? an escarpment?) as the sunrise overtook them. As it turned out, I first spotted them at about maybe 5:15 or so, and I stayed glued to that spot for a good three hours.

Changes occurred much more slowly than I had anticipated. While other features to the north and south of this mysterious line of dots rapidly revealed themselves as crater rims and gigantic peaks, the dots remained stubbornly unaltered as isolated points of light. They didn't merge together or expand in size, but rather multiplied in number. After maybe 20 minutes, there were four of them. then all of a sudden seven, as a tight little triangle of points popped out of the darkness all at once. It eventually became hard to keep track of how many there were, as a host of microdots gradually came on the scene. But for the longest time there wasn't even a hint of their ever joining up to form a recognizable landform.

Finally two set of dots merged into short arcs and the whole collection was assuming the appearance of a bow. I (entirely mistakenly) now assumed I was looking at a highly degraded rim of an ancient lava-flooded crater. And that's where things stood as the evening ended and I packed up to go home.

But that's not where the story ended. Once home, I shot out an e-mail detailing what I saw, and various club members responded with their ideas (a.k.a., guesses) as to the identity of the mysterious feature. It wasn't until Richard Orr sent me his image from Tuesday night (above) that a positive identification was made. I was observing the disconnected summits of an irregular line of hills just west of the crater Kunowsky. I went to Google Moon and turned on the Elevation feature. The feature jumped right out at me. It's also clearly visible in the chart by the incomparable selenographer, Antonin Rukl (right below this paragraph), centered at 36 degrees W, 2 degrees N. A photograph of the region can be seen here: , in which the feature appears right below and somewhat to the right of the crater Encke.

Unfortunately, whatever this landform is, it apparently has no name. At least, none that I can find. Richard noted that the dots were likely "small separate hills making the western boundary of Mare Insularum" but are not parts of a crater rim, nor of a mountain range. At this point, any speculations would be much appreciated!

* I didn't quite devote the entire evening to the Moon, since I began the session with a truly marvelous binocular view of Saturn and Mercury, both visible in a single field of view.

(Probably should have mentioned this earlier, but I was observing using a 90mm Stellarvue refractor on a Universal Astronomics Dwarfstar alt/az mount atop a Manfrotto tripod. No electronics whatsoever. I had to keep the object of interest centered by hand.)

Sunday, October 29, 2017

Star of the Month - November 2017

Alpha Piscium

This month's star is a challenge, both for your eyesight and for your equipment. Alpha Piscium (a.k.a., Alrescha), although only the 3rd brightest star in Pisces, is the linchpin that (visually, at least) holds the constellation together. You can find it on the star chart below off to the lower left corner.

The star itself is an extremely close binary (only 1.8" of separation) composed of 2 suns, each of which is approximately twice as massive as our own. They shine with a combined luminosity of 42 suns and are about 139 light years from our Solar System. They take nearly 700 years to complete one orbit about each other, and we happen to be living very near their closest approach (which will occur in 2060).

Although Alpha Piscium can be split in amateur telescopes, be prepared for a challenge. By comparison, the individual components of the famous "Double Double" (Epsilon Lyrae) near Vega in the constellation Lyra are separated by 2.6" and 2.3" respectively, and are often used as a test of one's ability to split double stars. So if you can see "daylight" between the 2 stars making up Alpha Piscium, give yourself (and your scope!) a pat on the back.

Saturday, October 28, 2017

Good things come in...

... small packages

(I posted much of the following content 4 years ago to the late and sadly-unlamented HAL Forum. It deserves a second look.)

At a distance of 14.1 light years, Van Maanen's Star in Pisces is the third closest white dwarf to the Sun, and the closest that is not a member of a binary system (Sirius B and Procyon B). This means its faint luminosity is not overwhelmed by a much brighter neighbor, and despite its 12.374 magnitude, it is therefore much easier to see.

Like all white dwarfs, Van Maanen's Star packs a lot of mass into a very tiny pace. With a diameter only slightly larger than the Earth's, it nevertheless has nearly two thirds of the sun's mass crammed into that tiny volume. It is believed that Van Maanen's Star began its life a little over 4 billion years ago as a main sequence star with approximately 2.6 solar masses. After a relatively brief time (less than a billion years), it swelled up into a red supergiant with a circumference roughly equivalent to Jupiter's orbit in our own Solar System, before collapsing upon itself into a white dwarf about 3 billion years ago.

Most intriguing is the star's abnormally high metallicity for a white dwarf. Astronomers speculate that perhaps a rocky, Earthlike companion to the star crashed onto its surface in the (astronomically) recent past, thus "polluting" its spectrum with the anomalous heavy elements.

Van Maanen's star is not too difficult to locate, but a real challenge to positively identify. For all you starhoppers out there, start by finding the 4.43 magnitude star Delta Piscium (Linteum), off of the southwest corner of the Great Square. Pass by two 6th magnitude stars to the immediate southeast of Delta Piscium, making a dogleg to the south-southwest to find the 5.75 magnitude star HD 4628, which sits squarely on the Ecliptic. About one-half full moon to the northwest of HD 4628 you'll see an anonymous 10th magnitude star, the brightest thing in the immediate vicinity. Van Maanen's Star lies due south of this last-mentioned beacon, about one-third of the distance between it and HD 4628.

For those of you with go-to, the coordinates for Van Maanan's Star are 
Right Ascension 00h 49m 09.90175and Declination +05° 23′ 19.0117″.

So if you haven't yet laid eyes on a white dwarf, this is your best chance for doing so! At the time of writing this, Van Maanen's star will be best situated for viewing any time after about 10 PM or so (9 PM after daylight saving time ends). I wouldn't attempt to see it with the Moon in the sky, however!

Saturday, October 21, 2017

Location, Location, Location...

NGC 752

I personally have spent many fruitless minutes (hours?) attempting to spot the inconceivably faint M33 from either Carrs Mill or Alpha Ridge, only to give up in frustration time and again. For every occasion on which I've successfully observed that most frustrating of objects through the eyepiece, there were at least a dozen failed attempts.

There are two reasons behind this sad ratio. The first, as I have already mentioned, is M33's unforgiving low surface magnitude. Although its apparent magnitude is listed as a whopping 5.72, which would normally make something an easy naked eye object, M33 is so close to our Milky Way that it spans an area of the sky more than 2 full moons across, thus diffusing all that brightness to the point of invisibility. (As J.R.R. Tolkien would say, "Like too little butter spread over too much bread.") So even moderate light pollution (such as we have in suburban Maryland) washes it out altogether.

The second reason why M33 is so difficult to locate is the lack of any signposts along the way for diehard starhoppers like myself. There are no recognizable asterisms to leapfrog from, no relatively bright stars from which to anchor one's search. It's just there, somewhere between the three naked eye stars that make up the Triangulum constellation, and the lower leg of Andromeda.

NGC 752

But there is something in M33's vicinity which is not at all difficult to find, and is extremely rewarding to observe - NGC 752, a beautiful open cluster just off to the left of the elusive galaxy. Why does this jewel of the heavens not get more attention? I believe it is a matter of its unfortunate proximity to both M33 and to its other close neighbor, M31 - probably the most observed galaxy in the entire sky. Sometimes location is a Good Thing, such as when your house is close to work, or convenient to grocery stores and coffee shops. But it can also be a curse, as when you're standing in the shadow of something far more famous and sought after. Who has the time (or motivation) to swing your field of view just a skosh to the side to take in yet another anonymous open cluster?

Well, let's do something about that anonymity, because NGC 752 is well deserving of your attention. First of all, it's both huge and bright. Despite its distance of 1,300 light years, it spans a nearly identical stretch of sky as M33 (about two full moons worth), and at magnitude 5.7 it's an easy naked eye object under dark skies. It is in fact often mistaken by binocular observers for M33 - they're that close!

But unlike the Triangulum Galaxy, which looks like a pathetic smudge of haze under even the most favorable of conditions, even a small amount of aperture will resolve NGC 752 into a spectacular splattering of about 60 stars of all conceivable colors and brightnesses.

NGC 752 is a very unusual open cluster. Instead of being the usual tens of millions (or at most a few hundred million) years old, NGC 752 clocks in at no less than 2 billion years old! This means that its various component stars have had time to experience all sorts of developmental changes. The cluster contains blue-white supergiants, red giants, middling stars like our own Sun, red dwarfs, and even a few white dwarfs - those aged stars which have already gone through all the usual stages of a star's life cycle.

But observe it while you can! The gravity of other stars in the Milky Way is gradually disrupting NGC 752 (thus accounting for its current huge size), and in another billion years or so, it will be only a memory.

Friday, September 29, 2017

Star of the Month - October 2017

Pretty much everyone in HAL knows that I have long been a huge fan of double stars. Indeed, the very first deep sky object that I recall ever seeing through a telescope was the venerable double star Albireo in Cygnus. My friend Craig Covault (of Aviation Week and Space Technology fame) had just been given one of the cheaper varieties of “department store” telescopes (a 3-inch refractor, if I remember correctly) as a birthday present by his wife Nancy. Her heart was in the right place, not knowing any better. And as a matter of fact, neither did we. In blissful ignorance of the instrument’s grave shortcomings, we set it up as soon as it got dark in the front yard of their Vienna, Virginia home. (This was in 1981, so the light pollution there was nowhere near as bad as today.) Craig knew enough to look for Albireo (I had never heard of it), and focused in on the star. When it came my turn to look through the eyepiece, I literally gasped. I was totally unprepared – not only for the wonder of the sight, but for the sheer beauty of it. The electric blue and warm gold of the star’s two components were like nothing I had ever expected; I could scarcely accept their reality. I was hooked for life.

To this day, I make a point of including a fair amount of double star viewing nearly every time I go out to observe. A night at the eyepiece just doesn’t seem complete without them. I have far too many favorites to list, but they include Albireo (still!), Iota Cancri, Rigel, the Double-Double in Lyra (of course), 18 Geminorum, Struve 2398, and many, many others too numerous to list… including this month's recommendation - Gamma Andromedae (a.k.a., Almaak, or even Almach).

Almaak is ridiculously easy to find in the night sky. Start with the star Alpheratz at the upper left corner of the Great Square of Pegasus. The constellation of Andromeda extends outward from that point, looking (to my eyes, at least) like a somewhat bent cone (see illustration).

Almaak is the last star to the left on the lower leg of the cone. Its 2.26 magnitude makes it easily visible even from my extremely light polluted location of downtown Baltimore (from which I am lucky to make out a mere dozen stars in the sky on a given night). A naked eye viewing may reveal little of its magic, but even a modest sized telescope (say, a 4 inch refractor) will present to the observer a true spectacle. What you will see is an easily splittable double star of amazing color. A bright golden yellow primary attended by... get this... a GREEN companion star. Yes, yes. I know there are no such things as green stars, but bear with me here. It turns out that γ2 Andromedae (the designation of the companion star) is itself a triple star, composed of a primary, orbited by two smaller suns that themselves orbit each other. So there are four stars in all making up what our unaided eye sees as one. If this seems too complicated, perhaps this schematic (not to scale) will help.

You may note that none of the stars that make up γ2 Andromedae are green. But even in the largest telescopes, they appear as a single point of light. And somehow their combined colors of blue, yellow, and orange combine in a way that the human eye perceives a lovely emerald hue.

There are other (apparently) green stars out there, but this is the most striking example.