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Another Planetary Double Star Apparition!!!

As if once wasn’t enough, another planet will be approaching closely enough to a star that it could easily pass for a double star — at least for one morning.  And whereas this one will lack the colorful contrasting colors displayed by the Uranus-44 Piscium apparition, it will more than make up for that in brilliance.

The two stellar objects responsible for what should be an eye-grabbing exhibition of white light are Venus and Regulus.   If you’ve been keeping an eye on these two for the last few weeks, you already know they’re drawing closer together.   Venus is the body in motion, and during the first few days in October, you’ll see it pull over into the passing lane and zip right past Regulus.  When it does, Venus will approach within grappling distance of 1.40 magnitude Regulus, which will seem pale and weak when placed next to Venus’s -4.10 magnitudes of brilliant white radiance.

On the morning of October 1st, the two stellar objects will be two degrees apart.  That will narrow to one degree on October 2nd, but the main event will take place the following morning when Venus slips to within three-tenths of one degree of  Regulus!  By the following morning, October 4th, the separation will have widened to 1.5 degrees, and twenty-four hours later, Venus will be well on its way beyond Regulus at 2.5 degrees of distance.   Even at that, it will still be a spectacular sight.

Depending on where you happen to reside on this planet, the separations will vary slightly due to the fact that Venus is moving so fast relative to Regulus.

Below you’ll find charts for the mornings of October 1st through October 4th, which will give you a tantalizing glimpse of what to expect when you face the east before dawn pales the sky.

Stellarium screen shots with labels added — click on either chart to enlarge it.

Here’s hoping you have clear skies for at least one of these mornings!

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UPDATE: 5 AM October 3rd, 2012

So there I was, standing in the middle of the street at 4:45 AM, looking at Venus — and Regulus was nowhere in sight.

I was staring directly into a very strong east wind that had driven the temperature from a crisp 41 degrees at 2:30 AM up to a balmy 52 degrees now, and Venus had more spikes coming from it than a pair of track shoes.  So I raised a pair of 10×30 Canon IS binoculars into that wind, and there was Regulus, almost directly above Venus!  So much white light!

I lowered the binoculars and looked again, and for just a very brief moment I thought I could detect Regulus.  Looking around for an occulting tool, I spied a pair of long fir tree limbs hanging over the street about fifty yards in front of me.  I moved a bit and tried to position Venus in the lower one, hoping that would block out its light enough for me to spy Regulus.  No luck — too much wind, too much movement, and too far-fetched to ever work anyway.  But I raised the binoculars up again to take another look and was treated to an eye-riveting three-dimensional image of two very close tree limbs framing the two dazzling white beacons in the pre-dawn sky.  What an exercise in perspective that was!  A distance of 50 yards for the tree limbs, about 67 million miles for Venus (.72 AU), and 78 light years for Regulus.

So concluding I hadn’t spied Regulus naked-eye wise, and wasn’t going to, the next question was how much distance separated the two objects.  I looked around for a measuring device, and found it near the moon –- Theta (θ) Tauri!  The distance between its two stars is 5.6 arc minutes, so I pointed the binoculars at them, imprinted the distance on my mind, turned back to Venus and Regulus and took another look.  Nope, they were very obviously farther apart than that.

What else?  How about the Delta (δ )Tauri Trio, δ-1, δ-2, and δ-3?   From Theta (θ),  I skimmed over the House of Hyades to the Taurian Delta, mulled over the distances between the three stars, and decided the interval between δ-1 and δ-2 was about right.  Back to the shimmering white lightning in the east for another look, up with the binoculars, and bingo!  I rotated back and forth about half a dozen times like an airport beacon, comparing the distance between Delta-one and –two with that of Venus and Regulus, and developed the impression that the pair of dazzling white lights were just a bit farther apart than the much dimmer Delta pair.

The distance between δ-1 and δ-2 is 13.8 arc minutes, so about fifteen or sixteen arc minutes for Venus and Regulus would be in the ballpark.  Of course they were only about twenty degrees above the horizon, and there was enough turbulence at that altitude that the binocular focus had to be adjusted slightly as I alternated between the two target areas.  Maybe their low position in the sky caused the Venus-Regulus separation to appear slightly wider than it actually was – not sure, and I haven’t come to any conclusion on that.

At any rate, Sky & Telescope put the separation for the two objects at eight arc minutes on the east coast, and Greg had them at about twelve arc minutes for the west coast in his description of the event – so again, we’re all in the same ballpark.  Stellarium proved to be the outlier, estimating the separation at about twenty arc minutes (1/3 of a degree).

If I had to make a comparison between this conjunction and that of Uranus-44 Piscium, it would be the colors that I found most striking.  The contrast between the blue of Uranus and the yellow of 44 Psc was remarkable, a slightly pastel version of Albireo, whereas Venus and Regulus was just a blaze of white light, most of it really coming from Venus.

Sure beats the heck out of being in bed at this hour of the morning!

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3 Responses

  1. I got a look at Venus this morning with binoculars and it was quite close to Nu Leonis, (27 Leo, SAO 98876), Mag 5.26 – a pretty sight. I should get the pairing with Regulus on the 4th before I go to work. Thanks for the “heads up,” no pun intended…

  2. Just updated the “Another Planetary Double Star Apparition” with a 5AM observation for October 3rd, the morning of closest approach.

    It was really quite a sight — you should have been there if you weren’t!

  3. Early this morning I got a look at Venus and Regulus. By 5AM this morning they had separated quite a bit.
    I used my binos on a tripod. They were pretty low in the sky and there were light high cirrus clouds moving in from the south. I confirmed it via this satellite web page: http://weather.hawaii.edu/satellite/satanim.cgi?res=4km&chnl=ir&domain=nep&size=large&period=720&incr=30&rr=900&satplat=goeswest&overlay=off&animtype=java
    At first I thought Regulus should be closer, too. Then I checked it with my SkySafari and they were about 22′ apart at that time. I also had a little trouble focusing the binos. On the tripod mount I would scroll the focuser in and out to get a clear view.
    They were closest before they rose. Somewhere in the world someone got a look at their closest conjunction…

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