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!
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.
RA: 13h 24m Dec: +54° 56′
Magnitudes A: 2.2 B: 3.9
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.