Category: Astronomy

Transit of Mercury — November 2019

The weather was perfect with clear skies and light winds in northern Arizona to photograph the transit of Mercury across the face of the Sun.

Transit of Mercury—11 November 2019
Transit of Mercury—11 November 2019

From Wikipedia: “A transit of Mercury takes place when the planet Mercury passes directly (transits) between the Sun and Earth, becoming visible against the solar disk. During a transit, Mercury appears as a tiny black dot moving across the disk of the Sun.”

Mercury is small so it is difficult to photograph a transit without using a telescope or large telephoto lens. I photographed the transit using a (1) full-frame Nikon DSLR and a 70-300mm telephoto zoom lens, and (2) a Panasonic Lumix FZ150 “bridge camera” with a 600mm [equivalent] zoom. The Nikon takes vastly superior images; the Lumix has more zoom. And the better results came from the Lumix.

The photograph above shows the first image taken as the Sun had partially cleared the cliffs. Subsequent images were stacked and aligned on this image so that it shows a sequence of positions during the transit.

Transit of Mercury-09 May 2016.
Transit of Mercury-09 May 2016.

The last transit of Mercury was 09 May 2016; the next will be 13 November 2032. The image above is from the 2016 transit.

Transit of Venus--05June 2012.
Transit of Venus–05June 2012.

Transits of Venus are easier to capture because Venus is much larger than Mercury and also closer to Earth. The last two transits of Venus were 05 June 2012 and 08 June 2004. The next transits of Venus will not occur until 10–11 December 2117 and 8 December 2125. Above is an image of the 2012 transit with a bird also “transiting” the sun.

Moon and Planets in the Evening Sky

On Monday and Tuesday (28-29 October 2019) the thin crescent Moon passed near the planets Venus and Mercury in the evening twilight sky. A check of The Photographers Ephemeris indicated that I could set up at Little Horse trailhead near Sedona and capture the thin crescent as it slipped between the spires of Cathedral Rock. Venus and Mercury would also be visible.

Ah, if only is was as easy as that. I never was able to see the crescent Moon.

A very thin crescent Moon sets behind Cathedral Rock.
A very thin crescent Moon sets behind Cathedral Rock.

But, wait! A closer inspection of the images shows that I did capture the crescent Moon. It was only 1% illuminated in a bright twilight sky. If you look carefully at the image and above the two people, you can just barely see a very thin crescent in the gap.

Venus and Mercury set behind Cathedral Rock.
Venus and Mercury set behind Cathedral Rock.

The next evening the Moon was 4% illuminated and higher in the sky making it an easy target. Venus and Mercury were below and the star Antares was to the left. Fitting all four objects in the image was the goal and I was successful. The only issue was the strong winds which resulted in some camera movement during the image capture.

Moon, Venus, Mercury, and Antares in evening twilight.
Moon, Venus, Mercury, and Antares in evening twilight.

I used Stellarium to determine how the Moon, planets, and stars would look at that time of the evening. I also used the Ocular plugin to show the field of view (FOV) of various lenses and focal lengths so that I could know, in advance, which lens would capture the whole scene. Very helpful!

Bright Objects in the Sky

The past few days have offered several opportunities for photographing objects in the sky.

Mercury and Venus in evening twilight.
Mercury and Venus in evening twilight.

Mercury (Magnitude –0.2) and Venus (Magnitude –3.9) are very low in the evening twilight right now and a bit difficult to see with the unaided eye—but a camera can do a better job at picking out the small but bright planets. The two planets are separated by about 7°.

Jupiter and the Moon in close proximity.
Jupiter and the Moon in close proximity.

At the same time, Jupiter (Magnitude –2.0) and the Moon made a close pass last night with about 2.5° of separation. These, of course, were much easier to see.

ISS passes in front of the Sun.
ISS passes in front of the Sun.

And, a few days ago, the International Space Station (ISS) flew in front of the Sun as seen from my house. I didn’t even have to travel—just set up the camera in the driveway. The entire flyby takes less than one second. Warning! A proper solar filter is required. I use a filter made by Kendrick Astro Instruments.

Milky Way Closeup

Most of my Milky Way photographs are shot using a wide-angle (24 or 28 mm focal length), or ultra-wide-angle lens (16 mm focal length). These create an image that shows a large portion of the Milky Way. But sometimes it’s fun to zoom in a bit and focus (no pun intended) on a much smaller section of the sky.

Milky Way.
Milky Way.

A few days after the full Moon provided a great opportunity to do this. The Moon would not rise until about an hour after astronomical twilight ended and, more importantly, there were very clear skies.

I used a Nikon D750 body with a Nikon 85mm f/1.8 lens for this session. This is designed to be a portrait lens but I find it makes a pretty good astrophotography lens as well because of the excellent light-gathering f/1.8 aperture and the corner-to-corner sharpness resulting in nice round stars. At least, that is, when I get sharp focus and accurate tracking.

I shot 10 images of 120 seconds exposure time and used Long Exposure Noise Reduction (LENR). I was unable to use the 10th exposure because the sky was already getting brighter even though the Moon was still below the horizon. The result was 9×120 seconds or 18 minutes of light gathering.

I have several different applications (both Mac and Windows) for star stacking and alignment and chose to use Starry Sky Stacker this time with good results. Once I had the stack completed I used rnc-color-stretch for histogram stretching with final postprocessing done in Lightroom 6/Photoshop CS6.

Milky Way with annotations.
Milky Way with annotations.

This is the final result. I think the colors might be a bit too saturated—but I don’t dislike the result. Artistic license invoked here.

Milky Way and Wupatki National Monument — July 2019

A few nights ago I had an opportunity to photograph the Milky Way under exceptionally clear skies. I wanted to do two things: One was to replicate an image I shot a few years ago and the other was to get a Milky Way/landscape composite with a moonlit foreground.

I headed out to Wupatki National Monument (an International Dark Sky Park) and set up in a dark parking lot with a moonlit landscape. The Moon was still well above the horizon and I took several long exposure images to get a good foreground. After the Moon had set, I shot the Milky Way (using a star tracker to eliminate star trails). Back at home, I would then merge the two images. The result is the image below showing the Milky Way aligned above the distant San Franciso Peaks with mesas rising on either side of the shallow valley. What also shows up is the large amount of light pollution in Flagstaff. Flagstaff is the worlds First International Dark Sky City but it takes a lot of work to keep the skies dark. I fear we may be losing the battle.

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

After completing this set of images, I moved to my next location to take my final shot. This is a single, 30-second image at high ISO (ISO 3200) with the tripod carefully centered on the stripe down the middle of the road. Comparing this shot with the one taken a few years ago indicates that the older image was blessed (if that’s the right word) with airglow in the lower part of the image giving it a much more interesting character. The newer image lacks this airglow but does have a more interesting horizon.

Road to the Stars II.

And now the North American Monsoon has begun to ramp up across the southwest and clear skies will be a rarity for the next few months. Time to start photographing storms and lightning!