Mercury Update - Details for 2018

Mercury has seven elongations in 2018. The initial sighting for each of these is tabulated below:


Initial Sighting Date (2017/18)

Observing Location

Greatest Elongation (2018)


December 24, 6:10 am EST Swede Run, Moorestown, NJ

January 1, western (morning)



March 15, eastern (evening)



April 29, western (morning)



July 12, eastern (evening)



August 26, western (morning)



November 6, eastern (evening)


    December 15, western (morning)


Elongation #1

The first sighting of the 2018 elongation cycle was on December 24, 2017, at Swede Run in Moorestown, NJ. It was initially seen with unaided eyes just above the tree tops at 6:00 am when it was magnitude +0.2 and 3 altitude. However, because the sky was generally cloudy with clearing mainly between streaky clouds along the eastern horizon, there were no visible reference stars to confirm the position. In particular, Antares was 8 from Mercury at the 4 o'clock position, and until I saw both objects, I couldn't be sure which was which. With 15x56 binoculars, I spotted Antares in the trees at 6:10 am, and over the next five minutes, it showed movement up and to the right, so it wasn't a distant antenna warning light (there are many antennae around Lockheed-Martin in that direction). Antares was also confirmed by spotting Aliyat (Sigma Scorpii) 2 from Antares at the 1 o'clock position.

The second sighting of the first elongation of 2018 was on December 28, 2017, at Swede Run, when the temperature hovered around 14F. It was initially seen with an unintentional glance of unaided eyes just above the tree tops at 5:55 am, when it was magnitude -0.2 and 3 altitude. A few minutes later, Antares was spotted 8.6 to the right of Mercury (at the 3:30 o'clock position), confirming the sighting. The image below, looking southeast down Westfield Rd towards the intersection of Borton Landing Rd, was captured at 6:04 am EST with a Canon 6D digital SLR camera and a Canon 100 mm f/2.8L macro lens on a fixed tripod. It was exposed 1 second at f/4, ISO 4000. It was cropped to about 75% of the original size for a field 15 wide x 10 high. Mouseover for labels. Mercury was still visible with unaided eyes when I left at 6:30 am.


The third sighting of the first elongation of 2018 was on January 1, 2018. First, I wanted to make sure I saw this 2018 elongation in 2018, not just 2017, and second, I wanted to catch Mercury on the day of its greatest western elongation, which is January 1 at 2:58 pm EST. We're still in a cold spell and the temperature hovered around 8F. Initially, I went to Swede Run in Moorestown, NJ. After picking up (4) Vesta (in Libra) with 15x56 binoculars at 5:45 am EST, I spotted Mercury in the treetops at 5:52 am with the 15x56s, then saw it with unaided eyes at 5:53 am; it was magnitude -0.3 and 2.3 altitude. After leaving Swede Run, I decided to check out the old Mart site in Pennsauken, NJ, which had been my workhorse morning twilight site until construction started there in August 2017. As soon as I pulled up, I could easily see Mercury through the windshield at 5.2 altitude. Based on what I could see in the semi-darkness of twilight (the sun wouldn't rise until 7:22 am), they were still preparing the ground at the Mart site as no visible structures had risen yet. When I arrived home at 6:25 am, Mercury was still easily visible at 7.4 altitude in brightening skies. Mercury's position viewed from home this morning was reminiscent of the first sighting in this series of observations back in January 2011.

The fourth sighting of the first elongation of 2018 was on January 14, 2018, from Swede Run during morning twilight with the temperature at 14F. I arrived at 6:15 am EST, and although the sky was generally clear, there was a band of clouds starting a few degrees above the tree line and ending below Jupiter and Mars, which were around 30 altitude. The Crescent Moon was in the band of clouds and popped in and out of view until it emerged from the cloud bank at 6:45 am. Regardless, glimpses of the moon through the clouds guided me to Mercury, which I picked up at 6:16 am with 15x56 binoculars. Saturn, a couple of degrees west of Mercury, also peeked in and out of the clouds and during the next ten minutes, I momentarily had Mercury and Saturn in the same binocular field several times. Finally, I was able to see Mercury with unaided eyes at 6:25 am, but I never caught Saturn with unaided eyes.



The current sighting streak is now 45 elongations in a row, starting in January 2011, which includes seven complete calendar years of six or seven elongations. The years 2011 and 2015 each had seven (7) elongations, while 2012, 2013, 2014, 2016 and 2017 each had six (6). Click here for previous sightings. 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.


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Last Update: Monday, January 22, 2018 at 08:49 PM Eastern Time