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 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.
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.
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.
The weather has been fairly typical for late June and early July: warm temperatures, breezy afternoon winds, and mostly clear and sometimes absolutely clear skies.
That will change dramatically over the next few days as the North American Monsoon ramps up across Arizona and the desert southwest. As subtropical moisture begins to move northward we will see a significant increase in cloudiness and thunderstorms. Clear night skies will quickly become a distant memory.
With that in mind, I took advantage of clear skies and did some Milky Way photographs. I decided to try Sunset Crater Volcano National Monument so that I could get some of the volcanic hills and ridges in the image.
Near the horizon is Mars which is becoming very bright in the evening sky—and will reach its peak brightness later in July. The planet Saturn is also visible within the starry mass of the Milky Way.
This is similar to an image taken last year in the same location and about the same date. As with that image, this is also a composite of two images. The first was taken of Cathedral Rock as the moon was setting in the west. An exposure of 120 seconds at ISO 400 and an aperture of f/4 was used. The second image was taken a short time later after the moon had set allowing the fainter stars in the night sky to appear. This image was 5 minutes at ISO 400 and an aperture of f/4. To prevent streaking of the stars an iOptron Sky Tracker was used. The two images were then blended together.
The past several weeks have presented opportunities to photograph objects in the night sky. Exceptionally clear skies and dark nights allowed me to capture some long exposures of portions of the Milky Way. Other nights had interesting alignments of the moon with one of more planets.
Early in September, Venus and Jupiter aligned with the Moon in a nearly straight line in the western sky just after sunset. Compare this with an image taken a month earlier. In the course of a month, Mercury has dropped below the horizon while Venus and Jupiter have switched locations with Venus rising higher in the sky as Jupiter dips lower.
Winter is slowly coming to an end and we are about to transition into the warmer months of spring and summer. During these upcoming months, the center of our galaxy—known as The Milky Way—will be rising earlier each evening.
For photographers—and just about everyone else, too—staring up on a clear, moonless night with the Milky Way glowing above can be a magical experience. For those who live in brightly-lit cities, however, the Milky Way can be difficult or even impossible to see. From an article at PBS:
Light pollution — the needless shining of bright lights into the night sky — has robbed whole generations of the chance to see nature on its largest scale. It is estimated that as many as eighty percent of all the people alive today have never even glimpsed the Milky Way. (When a massive power outage struck southern California in the 1990s, Los Angeles residents reportedly called 911 to express alarm about strange clouds hovering overhead; they were seeing the Milky Way for the first time.)
With the rapid advancement of digital cameras in the past decade the ability to take images of the night sky has become remarkably easier. Not easy—just easier. Cameras can now take long exposures at high ISO settings to reveal details of the night sky not easily visible to the unaided eye. This has resulted in magnificent photographs of the Milky Way but also other objects such as comets and Deep Sky Objects (DSO).
Still, long exposures of the night sky can result in the stars leaving streaks (i.e., “star trails”) across the image. This is the result not of the stars moving, of course, but the earths’ rotation. Typical wide-angle lenses used for photographing the Milky Way are limited to about 15 to 30 seconds before trails become obvious. In order to capture enough night-sky light at these exposures requires high ISO settings which can add considerable noise to the image. Of course, sometimes star trails are desired as seen in the image below:
Another option is to use a tracking device that follows the motion of the stars (or, more correctly, counteracts the rotational motion of the earth) allowing the camera to take very long exposures without star trails. The downside of this technique is while the stars remain pin points of light, the ground is blurred as the camera slowly moves during the exposure.
The solution requires taking multiple images: one of the stars with the star tracker on and a second image of the ground with the tracker turned off.
The image shown at the top of this post is a composite to two images: one of the stars and one of the ground.
The star image was taken using the iOptron Skytracker, a relatively inexpensive tracker. The image was shot using a low sensitivity (ISO 400) to minimize sensor noise. The lens was an ultra-wide 16mm shot at f/4 and the duration of the exposure was 534 seconds (~9 minutes). The exposure for the foreground was shorter in duration (4 minutes) and at a higher sensitivity (ISO 1600).
The two images were combined as layers in Photoshop. Masks were applied to each of the images and then blended so that the pin-point stars on one image and the sharp foreground of the other image remained.
It turns out that taking the images was the easy and fun part. Standing around in the middle of the night watching stars, meteors, and satellites cross the sky can be very enjoyable. Not surprisingly, the blending of the images took many attempts and much time.