Category: Skies

Autumn Equinox

Posted on by David Bookstaber

I happened to be in Salt Lake City during the equinox, where I learned that Utah has outlawed a lot of things. One random example: Happy Hour. Probably Utah also prohibits human sacrifices during equinox celebrations – I didn’t even bother to ask.

So aside from weird rules what else is there in Salt Lake City? Mountains. As my many readers know, I love to photograph interesting celestial events. So I went for a hike to get this equinox sunset:

Salt Lake City autumn equinox, 7500′ ASL

These foothills can be deceptive. I parked at one between the Big and Little Cottonwood Canyons and began to climb straight towards a peak. The first few hundred feet was fine gravel, so I had to kind of scamper from weed to weed to avoid sinking and sliding back. Then I reached sturdier ground which supports thickets of shrub-like oak trees. Those obstruct the view of what’s above, so I couldn’t be certain whether I had a good path ahead. I did eventually run into a trail bearing human footprints (though I saw no one else the entire hike). The trail wound back and forth between rocks and trees, and it was still very strenuous: When I got back I checked a topographic map and found that the straight-line route I followed from 5500 to 7500 feet averaged a 45 degree slope!

Perseid Meteors

Posted on by David Bookstaber
Perseid Meteors, composite image by David Bookstaber
Perseid meteors. That’s Jupiter near the middle of the frame.

I set up my old Sony A77II with an intervalometer for an hour and managed to capture these Perseid meteors. I was using my widest lens, 16mm, shooting ISO 1600 with 10 second exposures. It took some real work to post-process and compose this image: I had to find the frames with meteors and stack and align them in Photoshop. The result is nothing great for several reasons, including that (a) meteor shower photos should use a wider lens, and (b) should include a horizon or some ground feature for perspective.

It’s easier to get better results using a smartphone, not only because a typical smartphone has a very wide lens, but also because software can take care of identifying frames that contain meteors and aligning them. After the fact I checked the app store and found at least one cheap app that does this with a built-in “Meteor Mode.”

Shooting the Moon

Posted on by David Bookstaber
Waxing crescent moon shot with Nikon D3100, 500mm f/8 manual focus, 1/15 second at ISO 800

Last year I got a reasonably sharp photo of a full moon with a Nikon D7200 using the $500 Nikkor 18-300mm zoom lens at f/6.3, 1/160 second, ISO 160. This month I pulled out an old Nikon D3100 and a $100 catadioptric 500mm f/8 lens for a bigger challenge: The cheaper lens really falls short in terms of sharpness. Here is the best I could do with each lens (the more recent shot on the right is colored by atmospheric smoke from western wildfires):

  • Nikon D7200, 300mm f/6.3, 1/160 second at ISO 160
  • Nikon D3100, 500mm f/8, 1/8 second at ISO 800

But right now there are some interesting astronomical phenomena: Mars is near its closest approach to earth and is visible to the naked eye. Here the moon passes about one degree below the red plant (top left):

Mars, top left

I turned the camera on Jupiter, which is presently close to Saturn and very prominent in the night sky. With the same lens, shooting 1/2 second at ISO 800, I get the following photo showing all four Galilean moons:

Jupiter and moons Ganymede, Io, Europa (all left of the planet) and Callisto (far right)

I saw a Starlink satellite train!

Posted on by David Bookstaber

Last night after sundown I happened to be outside looking up at the waxing gibbous moon when I saw a satellite zipping near it in low earth orbit. And not far behind it another. And another – all spaced roughly 15 seconds (travel time, north to south) apart on the same orbit. They kept coming in what appeared to be an unbroken chain, and I could clearly see six to seven of them at a time. That’s an astonishingly dense satellite network, so it made me wonder if it was part of the astonishingly large LEO satellite network being built by Starlink.

Today I tried to confirm what satellites I could have been seeing, and it looks like there was indeed a Starlink train passing overhead at that time. The reason they were so close together is that Starlink satellites are launched 60 at a time in “trains” that gradually spread to the network’s operational altitude and separation. I must have spotted this one near the beginning of its transit of my location.

So that was very exciting, but I didn’t have equipment adequate to record it. Instead, here is a photo of a full moon I captured with a Nikon 7200 DX and 300mm lens last November:

Full moon photo by David Bookstaber