Mercury, Jupiter, and Saturn in the Evening Sky

A few weeks ago Jupiter and Saturn passed very close to each other during the Great Conjunction of 2020. Jupiter and Saturn are now pulling away from each other and are lower in the southwestern sky—but they have been joined by Mercury resulting in a planetary triplet viewable in the twilight.

Mercury, Jupiter, and Saturn in the evening sky.
Mercury, Jupiter, and Saturn in the evening sky.

This is a composite of three images taken over successive nights (09–11 January 2021) that shows the relative motions of the planets Mercury, Jupiter, and Saturn in the southwestern sky. The images have been aligned using Saturn as an anchor point.

Mercury, Jupiter, and Saturn on 09 January 2021.
Mercury, Jupiter, and Saturn on 09 January 2021.

From this composite, one sees small daily motions of Jupiter as it continues to move eastward away from Saturn—which had their Great Conjunction on 21 December 2020. Mercury exhibits large daily eastward motions as it races toward its greatest eastward elongation on 24 January 2021.

Objects in the Night and Twilight Sky—February 2020

The past few weeks have offered numerous opportunities for photographing objects in the twilight and night sky.

Venus and Mercury in the evening sky.
Venus and Mercury in the evening sky.

Above is a photograph showing the planets Venus (visible near the top of the image) and Mercury (located just below the center of the image). The glow of evening twilight on the horizon is reflected in the shallow waters of Mormon Lake.

Four planets and an asteroid.
Four planets and an asteroid.

Taken later on the same evening is a photograph showing four planets and an asteroid in a single frame. This was taken with a 24mm focal length lens to capture these solar system objects (SSO). I did this as a fun test to see if a wide-angle lens was able to capture these dim and distant SSOs. From top to bottom are the asteroid Vesta, Uranus, Venus, Neptune, and Mercury.

Zoomed-in crops (below) show the dimmer objects that are in the image above.

Zoomed in crops showing Vesta, Uranus, and Neptune.
Zoomed in crops showing Vesta, Uranus, and Neptune.

Before leaving that night I did a final wide-angle shot of the southeastern sky which included the constellation Orion as well as a portion of the winter Milky Way.

Wide-angle view of Orion and Milky Way.
Wide-angle view of Orion and Milky Way.
Pleiades star cluster.
Pleiades star cluster.

The following night I was out again to test my recently purchased Nikon 180mm Ć’/2.8 ED AIS manual focus lens. A few previous tests have shown that star images are pretty good at an aperture of Ć’/2.8 but much better at Ć’/4. At Ć’/2.8 there is just a hint of star spikes; at Ć’/4 they are quite prominent. This is a stacked sequence of images of the Pleiades star cluster. Image stacking was done with Starry Sky Stacker; histogram stretching was done with rnc-color-stretch.

Occultation of Mars.
Occultation of Mars.

On 18 February there was a Lunar occultation of the planet Mars. I had planned to get up early and drive to a dark location but an alarm failure meant I barely had time to get up and set up the gear on the rear deck of the house to start the sequence. Luckily, Flagstaff is a Dark Sky City and it was dark enough to get the shots. This is a sequence from just a few minutes before the Moon moved in front of Mars followed by a longer sequence after it reappeared.

Comet C/2019 Y4 (ATLAS)
Comet C/2019 Y4 (ATLAS)

Finally, Comet C/2019 Y4 (ATLAS) is in the northern sky making it an easy target—except that it is still very dim with a magnitude of about +12 at the time of this image. The still image is a stack of 49 images each 120 seconds duration at ISO 1600, 180mm, and Ć’/2.8. As noted above this lens is pretty good at Ć’/2.8 but better at Ć’/4. Because the comet is so dim I wanted the maximum light gathering ability so settled for an aperture of Ć’/2.8. Also in the image is M97 (“Owl Nebula”) and M108 (“Surfboard Galaxy”). The star Merak is part of the “Big Dipper.”

Also, there is an animation—made from the same images—showing the movement of the comet over a period of just under 2 hours.

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.