Thursday, August 25, 2016

Approaching Syzygy!

For those of you who have not seen the word syzygy before, in astronomy it is an alignment of 3 bodies in space - say for an eclipse or planetary transit. In today's case, this coming weekend on Friday AND Saturday nights (evening of the 26th and 27th of August) Jupiter, Venus and Earth will align. From our observing viewpoint on the Earth, Venus and Jupiter will align to a tenth of a degree on Saturday for some longitudes of the United States. By the time it gets dark in Arizona, It will be a little wider, as Venus will have already passed its big brother planet. But still, On Friday they will be within a degree of each other, and much closer Saturday, so certainly worth a look low to the west if it is clear.

And note too that while Venus and Jupiter look extremely close in the sky, physically they are no closer than normal. It is only from the Earth's viewpoint they even LOOK close. From us, Venus will be 144 million miles (233 million km), with Jupiter being 592 million miles (956 million km) distant. So Jupiter and Venus, while looking to nearly collide are actually 448 million miles apart! I'm sure some doomsayers will claim catastrophic things will happen, but nothing will, other than an interesting appearance in the sky! So syzygy will occur - the alignment of Earth, Venus and Jupiter!

If I may digress for a minute - the first time I heard the word was at the University of Iowa - not unusual in an astronomy department. But where it came up was in one of the first applications of a computer password - back in 1974, passwords were new sorts of things, and my boss thought that the word syzygy would be a great password. Turns out using it was a failure because most of the grad students, or for that matter, anyone who needed access to the system computer couldn't spell it correctly! Funny how you remember things like that from 40 years ago!

Anyway, with our currently clear weather, I went exploring for a place with good western horizons, and yet, providing some scenery to provide a nice backdrop for the conjunction (another word for a celestial alignment). As I've done before, I headed southwest of Tucson and south of "Three Points" on the Sasabe Road to put the profile of Kitt Peak National Observatory in the foreground. Arriving early to make sure I would find the perfect location to observe, the clouds that were there around sunset provided a spectacular display of color and crepuscular rays projecting into the sky, shown at left. The profile of Kitt Peak can be spotted about a forth of the way in from the left.

With the bright sky, I had trouble picking even the brilliant Venus out of the sky. I finally realized my new phone had a compass app, so used that and realized I was still too far north - the Venus/Jupiter pairing would occur almost due west, and Kitt Peak was still south of west for where I was located. Heading south a couple miles I relaxed in another potential spot till Venus was finally spotted, right above the Observatory profile. Unfortunately, as they set they move to the right for us in the northern hemisphere, so needed to fine-tune my position about a half mile back to the north. By now, Venus could be seen with the naked eye, and as it descended, I made one more adjustment of a couple hundred yards more to the north and then parked. From this final spot, Venus would just miss the Observatory to the right (north), but by Saturday (if I return) as Venus approaches Jupiter, both will perfectly set over the Observatory...

Finally I pulled out the tripods and a pair of camera lenses (the 70-200 zoom and the 300mm) I'd assembled during twilight. I had almost forgotten about Mercury being in the shot with the 200mm, so first went after that dim one down in the haze, shown and labeled at left. Also visible in the twilight is Beta Virginis, the second-brightest star in the constellation Virgo - the only non-planetary object I spotted...

Switching to the 300mm (I was using the full-frame sensor of the Canon 6D, so has a wider field with these lenses than my older APS sensor cameras), I then shot just Jupiter and Venus over the Observatory profile. Of course, Beta Virginis is still visible, as is the familiar (to me) outline of the observatory, from the solar telescopes at left to the flat-topped 90" of the UA and the big NOAO 4-meter telescope at right. As I had thought, Jupiter set adjacent to the 36" Spacewatch Telescope - pretty much right where I wanted it. Venus will move to the left to join it in a couple days and the pair will be perfectly positioned if the weather cooperates. An influx of moisture raises the chance of rain to 20% Friday and Saturday, so we'll see if I get to record the close approach those days - stay tuned!

Mars between Saturn at top and Antares below
After the planets to the west had set, I moved my attention to the planets to the south.  Mars and Saturn have been dominating the ecliptic to the south all summer, but now Mars was on the move.  As I mentioned in the post a few days ago, after the Earth has passed Mars, it is again in prograde motion, and its motion can be seen even by eye from day-to-day.  Drawing a line between Saturn and Antares, on Tuesday Mars was short (west) of the line.  Tonight (Wednesday), it was well past that line!  I was thinking I could show the motion even in a 135mm lens shooting at half hour intervals.  It was visible, but just barely, so don't show it here.  What I did do was take a trio of 2 minute exposures (yes, 6 minutes total at F/4 and ISO 2,000) and show the stacked results here, with some levels adjustment to optimize the view of one of my favorite spots in the sky.  Note also that the 135 lens was from my old Nikon optics collection from film days, using an adaptor for the Canon EF mount.

Since I'm still exploring the limits of the "newish" Canon 6D, I thought I'd push it a little bit. Since I was about 12 miles east of the Observatory, I kept the 135mm lens on the 6D at F/4 and pointed it at the barely visible outline of the mountaintop. Pushing the ISO to the ungodly 25,600, I was surprised to clearly see the noisy but easily visible outline of the Observatory at a 30 second exposure. Lowering it to a more reasonable ISO 2500 and upping the exposure to 2 minutes, a much more pleasing view was recorded. Cropped to provide a full-resolution image, you can see the coarseness of the high amplification at left, and the smoother but longer exposure at right...

I hate to leave an inviting dark sky, but finally headed home about 9:30 and was home 45 minutes later. Not a bad excursion, now knowing I've got a spot identified for a ringside seat to the planetary show this weekend if the weather cooperates!

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