Mercury Sightings - Details for 2021

Mercury has six elongations in 2021. The initial sighting by Joe Stieber for each of these is tabulated below:

Sequence

Initial Sighting Date (2021)

Observing Location

Greatest Elongation (2021)

#1

January 7, 5:13 pm EST Swede Run, Moorestown, NJ

January 23, eastern (evening)

#2

February 21, 5:56 am EST Swede Run, Moorestown, NJ

March 6, western (morning)

#3

April 23, 7:49 pm EDT Swede Run, Moorestown, NJ

May 17, eastern (evening)

#4

   

July 4, western (morning)

#5

   

September 14, eastern (evening)

#6

    October 25, western (morning)

  

Elongation #3

The first sighting of the third elongation for 2021 (the 66th elongation in a row overall) was on April 23, 2021 from Swede Run in Moorestown, NJ, under a clear sky without pesky clouds along the western horizon around sunset at 7:47 pm EDT. Mercury (magnitude -1.8) was initially sighted at 7:49 pm in moderately bright twilight with 15x56 binoculars (stabilized on a monopod) by looking about 2 below-right of bright Venus (magnitude -3.9), which was initially sighted at 7:45 pm in the 15x56s. When first sighted, Mercury was at 4.5 altitude, 5.2" apparent diameter, 97% illuminated. It was last seen when reached the treetops about 7:58 pm. Despite its bright magnitude, Mercury was not seen with unaided eyes, and even in the binoculars, there was minimal contrast with the fairly bright salmon-orange twilight sky. I think I glimpsed Venus before it reached the treetops at 8:05 pm.

The second sighting of the third elongation for 2021 was on April 26, 2021 from Carranza Field in Wharton State Forest, NJ, under a very clear sky without pesky clouds along the western horizon around sunset at 7:47 pm EDT. Mercury (magnitude -1.5) was initially sighted at 7:45 pm, a few minutes before sunset at 7:48 pm, in bright twilight with 15x56 binoculars (stabilized on a monopod) by looking about 1.6 above-right of bright Venus (magnitude -3.9), which was initially sighted at 7:38 pm in the 15x56s. When first sighted, Mercury was at 8.7 altitude, 5.3" apparent diameter, 93% illuminated. It was last seen when it reached the treetops at 8:15 pm, about 3.3 altitude. Neither planet was seen with unaided eyes.


Venus and Mercury from Carranza Field

 

The third sighting of the third elongation for 2021 was on May 1, 2021, from Swede Run in Moorestown, NJ, under a clear sky with only a few wispy clouds along the western horizon around sunset at 7:53 pm EDT. Mercury (magnitude -1.1) was initially sighted at 8:08 pm with handheld 8x56 binoculars by looking about 5 above bright Venus (magnitude -3.9), which was initially sighted at 8 pm with the 8x42s, then immediately seen with unaided eyes. Mercury wasn't seen with unaided eyes until 8:33 pm, after Venus dipped below the treeline, so both planets were seen with unaided eyes fairly easily, but not at the same time. When first sighted, Mercury was at 10.7 altitude, 5.8" apparent diameter, 81% illuminated.

The fourth through seventh sightings of the third elongation for 2021 were on May 8, 2021, from Camp Ockanickon in Medford, NJ, and May 10, 12 & 13, 2021, from Swede Run in Moorestown, NJ. In each case, Mercury was seen relatively easily with unaided eyes after initially finding it with binoculars. On May 13, the 2.3 day old crescent moon was just 3 to the left of Mercury, so I hoped to get a snapshot of them. Alas, there was a cloud mass above the horizon in that direction which largely obscured the view. At 9:35 pm, I noticed a glow in the clouds (about 4 altitude), aimed my 8x42 binoculars at it and saw the slim crescent emerge through the clouds, along with Mercury at the 4 o'clock position. I then looked with unaided eyes and saw them. Mercury was visible for half a minute or less, some portion of the lunar crescent for a few minutes. In the 8x42s, some earthshine was noted; I didn't even set up the camera.

 

Elongation #2

The first sighting of the second elongation for 2021 (the 65th elongation in a row overall) was on February 21, 2021 from Swede Run in Moorestown, NJ, under a clear sky without any pesky clouds along the eastern horizon before sunrise. Mercury was initially sighted at 5:56 am in moderately bright twilight with 15x56 binoculars (astronomical twilight began at 5:14 am EDT and sunrise would be at 6:44 am), then it was confirmed by spotting Saturn about 4 to the right of Mercury with the 15x56s. At the time, Mercury was at 3.4 altitude, 9.0" apparent diameter, 29% illuminated and magnitude +0.8 (nearby Saturn was magnitude +0.7). Using 60x in the 88 m apo spotting scope at 6:05 am, Mercury was just a wriggling blob that suffered significant atmospheric chromatic aberration, but was seemingly elongated from the upper left to the lower right. By 6:19 am, the atmospheric chromatic aberration was minimal and Mercury was vaguely a crescent with the cusps pointing to the upper right. The ansae of Saturn's rings were visible in the 88 mm scope at 60x. At 6:15 am, magnitude -2.0 Jupiter was spotted with the 15x56s behind the distant, leaf-bare tree tops at 2.5 altitude. None of the three planets was seen with unaided eyes.

The second sighting of the second elongation for 2021 was on February 25, 2021 from Swede Run in Moorestown, NJ, under a clear sky with a band of horizontal clouds just above the eastern horizon (in the direction of the objects of interest). Mercury was initially sighted with 8x42 binoculars at 5:55 am EST, then Saturn 4.3 to its right, with the 8x42s. Then, using unaided eyes, Mercury was spotted at 5:56 am and Saturn at 5:57 am, both with some difficulty in moderately bright twilight (since astronomical twilight started at 5:09 am and sunrise would be at 6:39 am). In the 8x42s, Mercury was star-like while Saturn looked like an elongated disc. Jupiter wasn't seen until 6:07 am, with the 8x42s and followed immediately with unaided eyes, after it rose out of the cloud band. It was definitely a disc in the 8x42s, and all three planets fit in the 9.1 field of the 8x42s. Easternmost Jupiter was 4.2 from Mercury and 7.7 from Saturn. At 6 am, Jupiter was magnitude -2.0. Mercury was +0.5 and Saturn was +0.7. When first sighted, Mercury was 4.7 altitude while Saturn was 5.2 altitude, well above the cloud band. Jupiter was 3.4 altitude when first sighted. Finally, Mercury was 8.4" apparent diameter and 39% illuminated.

The third sighting of the second elongation for 2021 was on March 3, 2021 from Swede Run in Moorestown, NJ, under a clear sky without any clouds along the eastern horizon. Mercury was initially sighted with 8x42 binoculars at 5:40 am EST, after first picking up brighter Jupiter, a little more than a degree below-left of Mercury. I then shifted the binocular view 7 to the right and up a little to find Saturn. Once found in the 8x42s, I was able to spot them with unaided eyes, and I was still able to see them through the windshield in brightening twilight at 5:55 am when I pulled out of my parking space. Astronomical twilight started at 5:00 am and sunrise would be at 6:30 am. In the meantime, I walked away from the car to get a better viewing angle and was able to see Denebola with unaided eyes towards the west. From there, I was able to spot the asteroid, (4) Vesta, with the 8x42s. When first sighted, Mercury was at 3.2 altitude, magnitude +0.2, 7.5" apparent diameter and 52% illuminated.

The fourth sighting of the second elongation for 2021 was on March 4, 2021 from Swede Run in Moorestown, NJ, under a clear sky with distinct haze along the eastern horizon. Mercury and Jupiter were initially sighted with 15x56 binoculars at 5:44 am EST, just 40 arc minutes apart. I then shifted the binocular view about 8 up and to the right to find Saturn. Once found in the binoculars, I was able to spot the three planets with unaided eyes, but with difficulty due to the haze. Astronomical twilight started at 4:59 am and sunrise would be at 6:29 am. I was also able to see Denebola with unaided eyes towards the west, and from there, I was able to spot the asteroid, (4) Vesta, with the 15x56s. When first sighted, Mercury was at 4.0 altitude, magnitude +0.2, 7.4" apparent diameter and 53% illuminated.

The fifth sighting of the second elongation for 2021 was on March 5, 2021 from Swede Run in Moorestown, NJ, under a clear sky. Mercury and Jupiter were initially sighted 8x42 binoculars at 5:44 am EST, just 21 arc minutes apart after their conjunction at 2 am. I then shifted the binocular view about 8 up and to the right to find Saturn. Once found in the binoculars, I was able to spot the three planets with unaided eyes, but with some difficulty due brightening twilight. Astronomical twilight started at 4:57 am and sunrise would be at 6:27 am. Just before that, I was able to spot the asteroid, (4) Vesta, with the 8x42s. When first sighted, Mercury was at 1.5 altitude, magnitude +0.2, 7.2" apparent diameter and 55% illuminated.


Jupiter and Mercury on March 5, 2021, at 5:39 am EST


The sixth sighting of the second elongation for 2021
was on March 20, 2021 from Swede Run in Moorestown, NJ, under a clear sky. I didn't plan any more observations this elongation, but was prompted to do so by Sky & Telescope's weekly planet roundup issued March 19, 2021, that said "Mercury had sunk out of sight into the glow of sunrise." I checked SkyTools and spotting Mercury seemed quite plausible on the morning of March 20 (see this page). As soon as I arrived at 6:32 am EDT (about an hour after the Vernal Equinox), I spotted Jupiter with unaided eyes in a somewhat bright blue twilight sky. Then i got out my 15x56 binoculars, and gliding up and to the right of Jupiter, I found Saturn. Both were identifiable in the 15x56s, Jupiter a definite disc and Saturn a smaller, but elongated shape due to the rings. Then moving below -left of Jupiter with the binoculars, I found Mercury at 6:35 am in brightish orange-white twilight just above the distant tree tops. Mercury was star-like and required some effort to pick out. Neither Mercury nor Saturn were seen with unaided eyes. Astronomical twilight started at 5:32 am and sunrise would be at 7:03 am. When first sighted, Mercury was at 3.0 altitude, magnitude -0.1, 5.9" apparent diameter and 74% illuminated.

 

Elongation #1

The first sighting of the first elongation for 2021 (the 64th elongation in a row overall) was on January 7, 2021 from Swede Run in Moorestown, NJ, under a clear sky (with just a few wispy clouds along the western horizon). Using bright Jupiter as a starting point, Mercury was initially sighted at 5:13 pm EST in moderately bright twilight with 8x42 binoculars (sunset was at 4:51 pm). At the time, Mercury was magnitude -0.9 and 3.9 altitude (about 5 from Jupiter at the 5:30 o'clock position).

Jupiter was was initially spotted at 5:12 pm with the 8x42s, then seen immediately with unaided eyes. Saturn was spotted with the 8x42s at 5:14 pm, about 2 from Jupiter at the 5 o'clock position. Subsequently, all three of these planets, Mercury, Jupiter and Saturn, were seen simultaneously in the 9 field of the 8x42s, but neither Mercury or Saturn could be seen with unaided eyes. Around 5:25 pm, I remembered to look up at Mars, which by then, was easy to see with unaided eyes in a darkening sky. Using Mars as guide as twilight deepened further, I found Uranus in the 8x42s about 5:35 pm, then a few minutes later using Fomalhaut as a starting point, I found Neptune with the 8x42s (so six planets in half an hour). At the other end of the night of January 7/8, I was  back at Swede Run before sunrise (7:22 am) and spotted Venus with unaided eyes at 6:25 am. When I arrived back at home before 7 am, I could see Venus with unaided eyes in the gap between houses across the street. So, all seven major planets (plus earth of course) were seen overnight.

In the interim, I stepped out front and spotted the minor planet, or asteroid, (4) Vesta with the 8x42s at 1:30 am on January 8 (then confirmed with my 16x70s). Vesta has brightened to magnitude 7.5 (a tad brighter than Neptune at magnitude 7.9) and will reach magnitude 6.0 (per the USNO's MICA software, 6.2 per SkyTools) at opposition on March 4, 2020.

The second sighting of the first elongation for 2021 was on January 10, 2021 from Swede Run in Moorestown, NJ, under a clear sky. Jupiter, Mercury and Saturn formed a compact triangle about 2 on each side. Mercury was at the lower-left vertex as shown the snapshot below, taken at 5:37 pm with a Canon EOS RP digital camera and a 200 mm lens on a fixed tripod. It was cropped to 64% from the original linear dimensions for a field 6.6 wide x 4.4 high. All three planets were seen with 8x42 binoculars; magnitude -2.0 Jupiter was visible with unaided eyes, magnitude -0.9 Mercury was glimpsed with unaided eyes and magnitude +0.6 Saturn was never seen with unaided eyes.


Jupiter, Mercury and Saturn on January 10, 2021, at 5:37 pm EST


The third sighting of the first elongation for 2021
was on January 12, 2021 from Swede Run in Moorestown, NJ, under a clear sky, but with distinct murkiness along the western horizon up to about 10 altitude. Mercury was now higher than Jupiter, and both were first spotted with 8x42 binoculars (in the same field) at 5:13 pm EST. I continued to observe until 5:30 pm, and neither was seen with unaided eyes, and nearby Saturn (lowest of the three) was not seen with unaided eyes or the 8x42s. All three of these planets remained at the same magnitude they were on January 7, 2021.

The fourth sighting of the first elongation for 2021 was on January 13, 2021 from Swede Run in Moorestown, NJ, under a clear sky, but with some murkiness along the western horizon. The evening's main objective was to spot a very young moon (17 hr old at 5 pm EST), which would have been difficult enough with clear skies, but with the murky horizon, virtually impossible. The extremely thin crescent (0.6% illuminated) was not seen using 15x56 binoculars on a monopod. However, with the 15x56s, Jupiter, 5 above the moon at 7 altitude, was spotted at 5:07 pm EST, while Mercury, about 3 from Jupiter at the 10 o'clock position, was spotted at 5:08 pm; both were followed until about 5:30 pm. Jupiter and Mercury were still at magnitude -2.0 and -0.9 respectively. Saturn, about 2 from Jupiter at the 5 o'clock position and magnitude +0.6 was not seen in the 15x56s, and none of the three planets was seen with unaided eyes. We are reaching the end of Saturn and Jupiter's visibility for this apparition; they will reach solar conjunction on January 23 and 28 (EST) respectively.

The fifth sighting of the first elongation for 2021 was on January 19, 2021 from the baseball field complex in Maple Shade, NJ, under a clear sky, which was also generally clear along the western horizon. Mercury was initially sighted at 5:27 pm EST (sunset at 5:04 pm) with 8x42 binoculars when it was at 10.5 altitude and magnitude -0.8. It was then seen with difficulty using unaided eyes at 5:29 pm. By 5:40 pm, it was no longer difficult to see with unaided eyes and at 5:45 pm, it was almost obvious in the deepening twilight. Saturn and Jupiter, 9 to 11 below Mercury, were never seen, even with binoculars they're getting too close to the sun now as they approach conjunction.

While there, I also looked for several other planets. Magnitude +0.2 Mars, about 18 east the nearly first-quarter Moon, was easy with unaided eyes at 5:31 pm. Magnitude +5.8 Uranus was picked up with the 8x42s at 5:48 pm, just 1.7 to the southeast of Mars (so they were easily in the same binocular field, even with the 15x56s). Mars and Uranus will be at conjunction in geocentric right ascension on January 21 at 19 hr EST, but their appulse (closest apparent approach) will be on January 20 at 13 hr, 1.6 apart. In any case, finding Uranus with binoculars is pretty easy now using Mars as a guide. Finally, I spotted a faint pinprick of magnitude +7.9 Neptune at 5:59 pm with the 15x56s. I had a rough idea of where it was about 1.5 east of Phi Aquarii, somewhere between a pair of sixth magnitude stars that formed an isosceles triangle with Phi Aqr. I noticed the pinprick using averted vision, then checked that location against a SkySafari chart and it matched.

 

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The current streak is now 66 elongations in a row in my eleventh calendar year of Mercury elongation sightings (beginning in January 2011). There are six or seven elongations per year. The years 2011, 2015 and 2018 each had seven (7) elongations, while 2012, 2013, 2014, 2016, 2017, 2019, 2020 each had six (6). 2021 will have six (6). Click here for sightings in 2020. The purpose of this ongoing effort is not to set some sort of record, especially since I have no idea what sort of record might exist, but to demonstrate that locating and seeing Mercury is not nearly as difficult as many suppose. It just takes some planning and a little effort, although circumstances make some elongations easy and some difficult.

 

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Last Update: Friday, May 14, 2021 at 12:08 PM Eastern Time