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

   

March 6, western (morning)

#3

   

May 17, eastern (evening)

#4

   

July 4, western (morning)

#5

   

September 14, eastern (evening)

#6

    October 25, western (morning)

  

  

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 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 64 elongations in a row to start 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: Tuesday, January 19, 2021 at 10:19 PM Eastern Time