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Mizar and Alcor – the greatest thing since sliced bread – and that’s not just a cliché!


My impromptu observatory in the snow.

Splitting Tools for Mizar and Alcor: This pair can be split with the naked eye if your sight is keen. It can certainly be split with any size, handheld, binocular.  Mizar itself is a double and can be split with a 50mm scope.

I’ll explain in a moment, but please let me set the scene. There are four inches of frozen snow on the ground, but in the afternoon I had freed the shutter and dome of the little observatory.  I would  have visitors at night – folks wanting to learn their way around the night sky,  and particularly be able to find the Messier objects –  but in the morning I expected to retreat to this, my sanctuary, and use the 8-inch SCT housed there.  Ah, but plans do get disrupted.  After a nice observing sessions with my visitors I got four hours sleep and was  out at the observatory at 2:45 am, tea and eyepiece case in hand. But I could not raise the shutter on the dome – frozen tight. Drat it!

The 50mm tube is nice flat black - Jack Frost did the spackling!

I was tempted to quit. Granddaughters – also visiting –  were asleep in the library and it is from the deck off the library that I frequently observe in bad weather.  But wait! I had cleared a little circle in the snow in anticipation of using it with visitors  – I didn’t, but there was enough room there to set up a small scope.  The Orion EQ-1 was in the telescope shed with a 60mm on it. I unscrewed that, then brought the little equatorial mount into the house and installed the adapter that had just arrived from Orion. This adapter made it possible to put on a small scope that used a 1/4-20  screw – just attach it like a camera to a tripod – and I had just the scope – my 50mm Tasco F12. This was the first piece of “classic glass” I had purchased and it had been slightly modified by the previous owner with a block with a 1/4-20 socket on the bottom. Perfect.

So in short order the Tasco was out in the yard with one leg of the EQ-1 tripod jammed through the snow crust and an observing chair next to it.  And now for Mizar!  I plopped in a 32mm Antares Plossl because the dinky straight-through finder on the Tasco would have required me to kneel in the snow. The 32mm gave me about 19X and  almost a 3-degree field of view. Pointing these longer scopes seems pretty intuitive, anyway. So I pointed the Tasco at Mizar – everyone knows, I’m sure, it’s the middle star in the Big Dipper’s handle, and  – bingo. There it was in the eyepiece – that very familiar view of three – no wait – four stars!  Mizar, Alcor, and what I call the “sidecar,” an eighth magnitude star that always seems to be part of the party to me, but has no physical association to the other two. But wait – there’s more.  Yep, you can split Mizar itself with just a 50mm scope and  19X. Cool!

So cool it brought a lump to my throat.  I thought – this is what the 14-year-old Greg  should have been doing back in the 1950s. But then he would not have had a mount like the EQ-1 and if he had had a scope like the Tasco he would not have had the patience to see the detail he sees now. So I guess this is the best of both worlds – having the experience of age and the enthusiasm of youth – enthusiasm supplemented by a few appropriate props like the little 50mm Tasco.  Mizar and Alcor are special – but they become more special when you use a small, but excellent piece of glass such as this 40-year-old Tasco. Oh – and yes, I switched to a 30mm Tak Le which made the bright stars sharper and that eighth magnitude “sidecar” clearer – just more throughput and better contrast with that eyepiece.

OK – I’ll get to the sliced bread shortly, but first, the numbers.

Mizar and Alcor
RA:  13h 24m   Dec:  +54° 56′
Magnitudes         A: 2.2    B: 4
Separation          11.8′ (708.5″)
Position Angle    71°
Distance:  78 LY
Spectral Classification: A1V/A5V

That’s the famous pair everyone thinks of when you say “Mizar ,”  and is easily split with binoculars and if you have better vision than I do, the naked eye. But, of course, Mizar itself  is a double and that’s what I was surprised to see yield to the 50mm at 19X. Guess I shouldn’t have been with 14.3″ separation and not even two magnitudes difference in brightness. A 12mm Orion Plossl gave a real nice view at 50X and a 12.5mm Tak LE a slightly better one. The higher power brought out the colors for me as well.

Mizar
RA:  13h 24m   Dec:  +54° 56′
Magnitudes         A: 2.2    B: 3.9
Separation          14.3″
Position Angle    153°
Distance:  78 LY
Spectral Classification: A1V

Now what about that sliced bread?

It’s a little memory device I use. I spend a lot of time showing off the night sky to folks and Mizar is a showpiece double of the first order, but I have trouble remembering things and to help me remember that these stars are about 80 light years away I associate them in my mind with the invention of sliced bread.  Store bought, already sliced bread was first marketed in the US about 80 years ago – a bit before my time, but as a kid one of our favorite sayings was  that something was  “the greatest thing since sliced bread.”   Wonder Bread was the first sliced bread on the market in 1930.

What makes Mizar the “greatest thing since sliced bread,” however, is both its place in history and what modern science reveals about it. I’ll let Jim Kaler explain. This is from his web site:

Mizar takes its place in the celestial hall of fame as the first knowndouble star, one that consists of a pair of stars that orbit each other. Found to be double in 1650, Mizar is a prime target for someone with a new telescope, as the components are an easy 14 seconds of arc apart (at least 500 astronomical units), the two taking at least 5000 years to make their orbit about each other. More remarkably, each of these two components is AGAIN double. The brighter of the two (magnitude 2.27) contains a very close pair a mere 7 or 8 thousandths of a second of arc apart (an angle made by a penny at a distance of 300 miles) that has an orbital period of 20.5 days; the fainter of them (magnitude 3.95) contains a pair with a period of about half a year. Mizar is thus actually a quartet of stars, a double-double. It is moving through space together with its more-distant companion, Alcor. Mizar and Alcor together therefore probably make a quintuple star, Alcor taking at least 750,000 years to make a single round trip around its quadruple companion.

Wow – now that is really slicing and dicing it. That one star we see – perhaps with its companion Alcor – is revealed to be two by the smallest of telescopes, but  when we look at  it we are really seeing a fantastic quadruple star.  And it’s beautiful too!

In the 50mm Alcor is amber, Mizar the palest of yellow to my eyes – its companion a rich light blue. Of course, your eyes may see something different. Haas has the Mizar pair as a “vivid pair of green-white stars” and she quotes Smyth as saying it’s “brilliant white” and “pale emerald.” Any star that can show all those colors to folks while still keeping some secrets is certainly the “greatest thing since sliced bread.” And viewing it, old friend that it is, always gives me a thrill. It’s my favorite double.

OK – I have to admit, “favorite double” comes with an asterisk. See, I heard the poet Robert Frost was once asked what was his favorite poem and he answered something like this – “either the one I just wrote, or the one someone just praised.” My favorite double is the one I just split, or the one that just elicited a “wow” from a visitor, looking at it for the first time through a telescope. Come to think of it, that definition pretty much fits my favorite telescope too! And right now that little Tasco 50mm is my favorite – I even went on to use it to split  Algieba and Castor.

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2 Responses

  1. 1AM, January 22nd

    Bright moon outside, 40 degrees, and lots of fluffy white clouds racing across the sky. It’s been raining all day and pretty much quit a few hours ago, but every now and then a brief shower comes out of those clouds. It’s rained here so much the past two and half months that it doesn’t seem to know how – or when – to quit.

    So – the question is, do I chance it or not? It wouldn’t be the first time I got rained on while trying to get a quick look – but it’s not something I recommend for a telescope!

    After getting a scope ready in the house and debating with myself for another half hour, I decide to risk it.

    So out I go onto a very wet deck with a 72mm AstroTech refractor mounted on an old Polaris mount and a stout wooden tripod. I have four eyepieces in bolt cases stowed in my pockets: 16.8mm, 10.5mm, and 7mm Faworski Orthos, and a Tak 5mm LE.

    I start a quick tour of the sky, guided by wherever the holes in the clouds are, and after about thirty minutes of that, I’m beginning to think about giving up since the clouds aren’t. But as I turn around towards the north, what do I see twinkling back at me but Mizar!

    Aha! A huge hole in the clouds, too!

    So I spin the scope around to the north quickly, get lined up, look into the 16.8mm eyepiece (26x), and there it is – Mizar A and B just barely split, with the moonlit sky peeking out between them, and Alcor over in the other corner of the eyepiece.

    I shift gears to the 10.5mm (41x) and take another look. Still a pleasing sight, but I prefer a bit more distance between the Mizar pair, and I swap the 7mm (61x) into the diagonal.

    Wow! I drop into my observing chair and just stare – Mizar has me mesmerized now. Actually, to be fair, it’s the scope that has done it.

    I haven’t spent much time with this diminutive little devil because the weather didn’t cooperate for about five weeks after I got it, and then I used it mainly as an over-sized finder on top of another scope. So I’m just beginning to get familiar with this small white tube.

    What amazes me is how it’s both a great wide field scope and a great double star scope. Usually those two things aren’t done well by a single scope. But this one does both – and extremely well.

    A 25mm Plössl gives me almost a three degree field of view and 17x. Star fields at that magnification are just ravishing. The dimmer ones are like the heads of silver pins gleaming from the top of a pin cushion – just very fine, brilliant points of light.

    And doubles at high magnification in it leave me searching for words to describe the experience – as is the case now when I place the 5mm Tak (86x) in the diagonal. The bright sky background, caused by the moon and also by the moisture in the air which is scattering its light, makes both the Mizar pair and Alcor look white – and the contrast between those startlingly white globes of light and the bright sky has me completely captivated.

    I sink into my chair and don’t move from it for about fifteen minutes.

  2. 1:30 AM, June 9th

    I’ve got a 60mm scope I’ve been trying to put together for a couple of weeks, but all my attempts to find a lens that will work have been a dismal failure so far. Yesterday I picked up a Carton 60/910 lens from the post office and took it home with hopes that this one would save the day — or the night, to be more precise. After I had it installed in the scope, I tested it quickly with my small Hubble flashlight I use for checking collimation and image quality, and it looked pretty darn good.

    But the final test required some real stars — which have been rather rare around here for the last few weeks.

    And that’s why I’m sitting out here in the dark under a cloudy sky beside a long white 60mm tube. According to the Clear Sky Chart and the NOAA infrared photos, it was supposed to clear up two hours ago. But — it hasn’t, although the clouds seem to have gotten thinner.

    After thirty minutes of craning my neck in every direction imaginable, I finally hit on the idea of using a laser pointer to see if I can detect how low the clouds are. And hey, it works — it actually reflects off the clouds! But since it isn’t carving any holes in them, I sigh and put it away.

    But maybe the effect is only delayed. About ten minutes later, the clouds begin to thin out and stretch apart and I can see a few glimmers of hope. Arcturus breaks through a couple of times, and a few minutes later, most of the handle of the dipper asterism in Ursa Major is visible.

    So I swing the long white tube up to Mizar, put a 20mm TV Plössl (46x) in the diagonal, adjust the focus, and Holy Mizarian Miracle, I’m rewarded with two very small, bright, very well defined points of white light, along with Alcor hovering at one edge of the eyepiece. Now I haven’t been treated to any kind of photonic display for well over a week, so it could be that my eyes are so overjoyed they’re sending spurious signals of delight. But considering what follows — probably not.

    The clouds cover Mizar almost immediately — as well as the rest of the sky — but I can still see both of those Mizarian points of light through the thin layers. At times the 3.9 magnitude “B” component almost fades from sight, but then suddenly it brightens up again as the density of the clouds change. And the “sidecar” that Greg refers to in his post above is visible most of the time. I look up from the eyepiece every few minutes, and most of the time, Mizar is invisible or right at the edge of visibility. Not bad for a 60mm lens!

    I sit still for about fifteen minutes, watching as Mizar fades, brightens, fades, etc, until finally it’s gone. So I’ll rate the Carton lens an A+, find a better focuser for the tube, mount a 6×30 finder on it, and put this thing on my Celestron six inch refractor. In fact, I think I’ll paint it black to match.

    With two black scopes attached to a black mount, I should pretty much be invisible out here at night.

    Provided I’m not waving that green laser at the clouds.

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