Milky Way, Moon, and Mercury

It’s that time of year when the Milky Way is visible through much of the night. It is best observed when there is no Moon in the sky—and from very dark skies away from areas of light pollution. I wanted to capture both the Milky Way in a very dark sky and to capture Moonlight gently lighting up the still partially snow-covered mountains. So I headed out to Kendrick Park for some midnight sky photography.

The Milky Way rises above the San Francisco Peaks in northern Arizona.
The Milky Way rises above the San Francisco Peaks in northern Arizona.

The result is this composite of two images. The first was taken of the San Francisco Peaks as the moon was low in the west at around 1118 MST. This was a bit more than an hour before moonset (0030 MST). An exposure of 300 seconds at ISO 800 and an aperture of f/8 was used.

The second image was taken at 0047 MST shortly after the moon had set allowing the fainter stars in the night sky to appear. This image was also 300 seconds at ISO 800 and an aperture of f/5.6. To prevent streaking of the stars an iOptron Sky Tracker was used. The two images were then blended together.

This is similar to images taken in the past of Cathedral Rock and Wukoki Pueblo with the Milky Way rising above. Also present low in the photograph is airglow (or nightglow).


Last week the two-day old crescent Moon (only 3.7% directly illuminated) provided a photo opportunity as it set over Upper Lake Mary. During the months of May, June, and July, the thin crescent Moon lines up with the long axis of Upper Lake Mary. This results in nice reflections of the Moon on the waters of the lake—but only if there is little or no wind. A bonus this month was the small planet Mercury was also setting in the northwest.

A thin crescent Moon throws a large reflection in Lake Mary, Flagstaff, Arizona.
A thin crescent Moon throws a large reflection in Lake Mary, Flagstaff, Arizona.

The image also shows the unlit part of the crescent Moon illuminated with Earthshine, also known as Da Vinci Glow. Yes, that Leonardo Da Vinci. Mercury can be seen just above the treetops on the far right side of the image.

Clear Skies Make it a Good Time to View the Zodiacal Light

With exceptionally clear skies it was a good time to capture images of the zodiacal light. Here is what Wikipedia has to say about this astronomical phenomenon.

Zodiacal light is a faint, roughly triangular, diffuse white glow seen in the night sky that appears to extend up from the vicinity of the Sun along the ecliptic or zodiac. It is best seen just after sunset and before sunrise in spring and autumn when the zodiac is at a steep angle to the horizon. Caused by sunlight scattered by space dust in the zodiacal cloud, it is so faint that either moonlight or light pollution renders it invisible.

Zodiacal Light. (28mm lens)
Zodiacal Light. (28mm lens)
Zodiacal Light and light pollution. (16mm lens)
Zodiacal Light and light pollution. (16mm lens)

Both images above clearly show the cone of light extending upward. In the upper portion of both images is the Pleiades star cluster with the planet Mars just below and to the left.

Light pollution from Phoenix makes star viewing a challenge.
Light pollution from Phoenix makes star viewing a challenge.

It’s unfortunate that Arizona’s dark skies aren’t as dark as they could be. Increasing population and expanding cities throws more light into the night sky. And our state legislators seem to think that bright billboards are more important than the dark skies needed by the many telescopes located in the state.

Comet C/2018 Y1 (Iwamoto) Moves Across the Winter Sky

Comet C/2018 Y1 Iwamoto has just made its closest approach to Earth this week. With one evening of clear skies forecasted before the next storm system moves into the area, I went out earlier this week (02/11/2019) to capture images of this fast-moving, blue-green comet. The Moon was up in the western sky with 38% of the disk illuminated. This caused considerable brightening of the sky and made it challenging to capture fine details of the comet.

Comet C/2018 Y1 (Iwamoto).
Comet C/2018 Y1 (Iwamoto).

From Universe Today:

Discovered by Japanese amateur Masayuki Iwamoto as a +12th magnitude fuzzball moving through the constellation Hydra the Water Serpent on the night of December 18th, 2018, Y1 Iwamoto is a fast mover. It’s great to see that amateur astronomers can and still do discover comets, as the robotic competition posed by automated surveys such as PanSTARRS makes such an independent discovery tough these days…

At its closest on February 13th, Comet Y1 Iwamoto will appear to move seven degrees a day. This translates into a fast apparent motion of about 2/3rds the apparent diameter of a Full Moon, every hour.

The comet was easy to find with a pair of binoculars but was not visible to the unaided eye. Its position on this evening was near enough to the bright star Regulus that I had no trouble aligning the camera.

The following image and animation show the motion of the comet during a period of just over one hour.

A one-hour composite of C/2018 Y1 (Iwamoto) showing the rapid motion of the comet.
A one-hour composite of C/2018 Y1 (Iwamoto) showing the rapid motion of the comet.

Time lapse movie showing the motion of C/2018 Y1 during a period of one hour.

Comet C/2018 Y1 Iwamoto will make its next passage through the inner solar system in 3390 AD.

Lunar Eclipse Through the Clouds

I have been looking forward to the recent Lunar eclipse (20 January 2019) since, well, the last one actually. During that eclipse, I shot images every three minutes while using an equatorial mount to track along with the stars. The results were good but there was some room for improvement. And that’s why I was looking forward to this event.

Lunar eclipse of 20 January 2019.
Lunar eclipse of 20 January 2019.

The weather had different plans for me. A stream of high-level tropical moisture was sitting right over Arizona all that day and most of the night. By late afternoon, the clouds were thick enough to partially obscure the sun. How was a darkened Moon going to shine through those clouds?

I could have just given up and stayed home but I was determined to at least try. I drove to Sedona to set up. Not because Sedona is a better place for viewing than Flagstaff but because Sedona is about 15 degrees warmer. And that matters.

I set up the tripod and then roughly aligned the iOptron Skytracker to where I made my best guess of the location of the star Polaris. Just as the umbral phase of the eclipse began, I was able to barely see Polaris through the thin clouds and completed the alignment of the tracker.

One of the things I learned last year was that three minutes was too large a time gap to make a smooth time-lapse video. My plan for this eclipse was to shoot at 1-minute intervals. But with the high clouds I realized that any time-lapse video was going to be challenging. So…3-minute intervals again. The clouds varied between fairly thick and mostly obscuring the moon to occasionally very thin allowing some lunar detail to be seen.

Satellite image showing extensive clouds during the Lunar eclipse.
Satellite image showing extensive clouds during the Lunar eclipse.

Here is a satellite image from GOES-16 showing the incredible stream of clouds moving across Arizona. I’m amazed that I got any photos at all!

Another look at Comet 46P/Wirtanen

Comet 46P/Wirtanen has already made its closest approach to both Earth and Sun and is now moving away. Yet it remains high in the sky making it an easy night-sky object if you are in a very dark location. It then appears as a full moon-sized smudge in the sky.

Comet 46P/Wirtanen. (Nikon D750; 200mm; f/4; ISO 1600; 120 seconds)
Comet 46P/Wirtanen. (Nikon D750; 200mm; f/4; ISO 1600; 120 seconds)

The full moon is now waning and rising later so that there are a few hours in which to observe the comet without the interference of moon light. We had one night without moon interference and without clouds so I took advantage.

Instead of taking multiple images and stacking I shot single images of 1, 2, and 3-minute exposure. Should have been easy. But there was a gusty wind blowing so that the camera and tripod was sometimes jostled resulting in streaky stars. And I had trouble focusing the telephoto lens I wanted to use (Nikon 70-300mm). Frustrated and cold, I grabbed my legacy zoom lens (Nikon 80-200mm AIS Manual Focus). This one is easy to focus on stars. Just rotate the focus ring all the way until it stops.

That’s the thing about some legacy manual focus lenses. They can be easier to focus than modern auto focus lenses in the dark so I keep several very old lenses around for that reason.