SJAstro Page Index
Mercury Update - April 2018
seven elongations in 2018.
The initial sighting for each of these is tabulated below:
December 24, 6:10 am EST
Swede Run, Moorestown, NJ
January 1, western
February 26, 5:56 pm EST
Baseball Fields, Maple Shade, NJ
March 15, eastern
April 22, 5:26 am EDT
Old Mart Site, Pennsauken, NJ
April 29, western
July 12, eastern
August 26, western
November 6, eastern
December 15, western
Click here for the sighting
details of each elongation this year. The current sighting streak is now
47 elongations in a row, starting in January 2011, which includes seven
complete calendar years of six or seven elongations each. The years 2011
and 2015 had seven (7) elongations each, while 2012, 2013, 2014, 2016
and 2017 had six (6) each.
Click here for sightings from last year's elongations. This demonstrates that locating and seeing
Mercury is not nearly as difficult as many suppose. It just takes some
planning and a little effort.
The Crescent Moon in the Hyades
April 18, 2018
The two-day-old, 11% illuminated and earthshine-filled Crescent Moon
was in the Hyades star
cluster on April 18, 2018,
when this image of them was captured from Maple Shade, NJ, at 8:54 pm
EDT, 74 minutes after sunset in a hazy sky, soon to become cloudy. This
is a single frame taken with a Canon 6D digital SLR camera
and a Tamron 150 to 600 mm f/5-6.3 zoom lens (on a fixed tripod) set to
250 mm focal length, then cropped to about three-quarters of the
original frame, producing a field 5.5° wide x 4.9° high. It was exposed 1.6 seconds at
f/5.6, ISO 1600. Mouseover for labels. All of the stars here are in
Taurus the Bull, so the labeled Bayer letter or Flamsteed number would be suffixed "Tauri."
The labeled V-shape encompasses the Hyades and represents the face of
the Bull. The horns would extend about 15° more-or-less vertically from
Aldebaran (α) and Ain (ε) to Zeta (ζ) and Beta (β) Tauri respectively (β
Notice the magnitude 5.6 star, 63 Tauri, just above the moon. I saw it
near the lunar limb on the camera's viewing screen during the session,
and reviewing circumstances afterwards with SkyTools, saw that it was
occulted by the moon at 9:08 pm (the moon is moving eastward, nominally
to the upper-left in this view, about about its own half-degree diameter
per hour). Looking through the images, the last
one with 63 Tauri visible (below) was time-stamped 9:07 pm.
63 Tauri had vanished in the following frame that was time-stamped 9:08 pm
(not shown). Taken with a Canon 6D digital SLR camera, which has an
internal GPS that sets the clock, and a Tamron 150 to 600 mm f/5-6.3 zoom lens (on a fixed tripod) set to
205 mm focal length, then cropped to about one-quarter of the original
frame, producing a field 2.7° wide x 1.8° high. It was exposed 1.3 seconds at
f/5.6, ISO 800. Mouseover for labels.
Venus and Uranus
March 30, 2018
The planets Venus and
Uranus were at conjunction
on March 28, 2018, and less then 5 arc minutes apart after sunset.
However, it was cloudy that night, as it was on the preceding and
following nights, March 27 & 29, when they were little more than 1°
apart. Finally, on March 30, 2018,
despite rain in the afternoon and a poor weather forecast for the
evening, it cleared out nicely shortly before sunset at 7:22 pm EDT.
This picture of them was taken at 8:13 pm from the baseball field
complex in Maple Shade, NJ, with a Canon 6D digital SLR camera and a Canon 200 mm f/2.8L
lens (on a fixed tripod), then cropped to about half the original size
for a field 5.0° wide x 3.7° high. It was exposed 0.8 second at f/8, ISO
In the picture, brilliant Venus is shining
at magnitude -3.9, so it's overexposed and shows a crown of
diffraction spikes generated by the lens diaphragm. The magnitude +5.9 star HD
11257 is 15 arc minutes from Venus at the 1 o'clock position, the
magnitude +4.3 star Omicron Piscium is 2.1°
from Venus at the 7 o'clock position and barely-visible magnitude +5.9
Uranus is 2.3° from Venus at the 5 o'clock
position (mouseover for labels). At the time of the picture,
Venus was at 8.2° altitude and Uranus was at 6.0° altitude. Venus is
moving eastward from the sun, and becoming higher in the evening sky,
following superior conjunction on January 9, 2018. Uranus is dropping in
the evening sky and will be at conjunction with the sun on April 18,
The 9.8 magnitude difference between Venus and Uranus is equivalent to
a difference of 8,300 times in brightness, or 13 photo stops, hence the
difficulty in showing them both with a single exposure and no
localized processing to enhance Uranus. In addition, the difference in
the already-low altitude causes greater atmospheric extinction of
Uranus, and the noticeable twilight gradient also diminishes Uranus'
visibility in the photo. Uranus and Omicron Piscium could not be seen
with 16x70 binoculars during the March 30 session from 8:00 and 8:30 pm.
My last visual sighting of Uranus (using an 80 mm apo refractor at 72x)
was on March 26 when it was about 2.4° above Venus. It was not easy to
The Crescent Moon, Venus and Mercury
March 18, 2018
The 1.5-day-old Crescent Moon
joined the planets Venus
and Mercury in this view
on March 18, 2018, from
Swede Run in Moorestown, NJ, at 8:01 pm EDT, 51 minutes after sunset.
The Moon was at 4.3° altitude and 2.5% illuminated. Venus, 3.9° from the
moon, was at 5.3° altitude and magnitude -3.9. Mercury, 3.8° from Venus,
was at 7.2° altitude and magnitude +0.4. It's a single uncropped frame taken with a Canon 6D digital SLR camera and a Canon 200 mm f/2.8L
lens (on a fixed tripod). It was exposed
1/10 second at f/2.8, ISO 1600, daylight white balance. Mouseover for labels.
Here's my 2018 Mercury sighting page.
Venus and Mercury
March 3, 4 & 5, 2018
In early March 2018, both
Mercury were in
eastern elongation and were visible low in the west after sunset. At
time, Mercury was moving eastward more rapidly than Venus and passed it,
reaching conjunction in geocentric right ascension on March 5 at 1 pm
EST. Their appulse (closest approach) for an observer at 40°N-75°W, only
a few miles from Maple Shade and Moorestown, NJ, would be on March 4 at
1 am EST. The closest visible approach was on the evening of March 3
when they were 1° 05' apart at 6:30 pm EST. On March 4, they were 1° 09'
apart and on March 5, they were 1° 29' apart at 6:30 pm. During these
three days, Venus was at magnitude -3.9 while Mercury was at magnitude
-1.2 on March 3 & 4, magnitude -1.1 on March 5. Venus was seen with
unaided eyes on all three dates, but obvious on the clear evenings of
March 4 & 5. Mercury was also readily visible with unaided eyes on March
4 & 5. Of particular note on March 5, both were seen with 10x50 binoculars
at 5:52 pm, 4
minutes before sunset, when Mercury was at 13.5°
altitude. Check the
Mercury 2018 page
for more details about visual observations on these dates, under Elongation #2.
The pictures below show Venus and
Mercury on March 3, 4 & 5, 2018. The scale
varies a little between them, but they clearly show Mercury (on the
right) increasing in altitude relative to Venus on successive evenings. Mouseover for
March 3, 2018, at 6:36 pm
EST (42 minutes after sunset) from the baseball field complex in Maple
Shade, NJ. Canon 6D
digital SLR camera (on a fixed tripod) and a Sigma 70 to 300 mm, f/4-5.6
zoom lens set to 300 mm focal length, then cropped to about 60% of the
original size (and a 16:9 ratio), which yielded a field about 4.6° wide
x 2.6° high. It was exposed 1/6 second at f/5.6, ISO 800.
March 4, 2018, at 6:37 pm
EST (42 minutes after sunset) from Swede Run in Moorestown, NJ. Canon 6D
digital SLR camera and a Canon 70 to 200 mm, f/2.8L zoom lens (on a
fixed tripod) set to 190 mm focal length, then cropped to about 65% of
the original size (and a 16:9 ratio), which yielded a field about 7.5°
wide x 4.3° high. It was exposed 1/20 second at f/2.8, ISO 800.
March 5, 2018, at 6:40 pm
EST (44 minutes after sunset) from the baseball field complex in Maple
Shade, NJ. Canon 6D digital SLR camera and a Tamron 150 to 600 mm
f/5-6.3 zoom lens (on a fixed tripod) set to 329 mm focal length, then
cropped to about 84% of the original height (for a 16:9 ratio), which
yielded a field about 6.2° wide x 3.5° high. It was exposed 1/4 second
at f/5.6, ISO 1600.
for the previous page.
for an index to previous SJAstro pages.