Zodiacal Light 2018

In this year of 2018, the best dates and times for observing the zodiacal light are listed below.  The sky must be very clear.  The specific times listed are for Dodgeville, Wisconsin.

2018 Begin End Direction
Fri. Feb. 2 6:52 p.m. 7:52 p.m. West
Sat. Feb. 3 6:53 p.m. 7:53 p.m. West
Sun. Feb. 4 6:54 p.m. 7:54 p.m. West
Mon. Feb. 5 6:55 p.m. 7:55 p.m. West
Tue. Feb. 6 6:57 p.m. 7:57 p.m. West
Wed. Feb. 7 6:58 p.m. 7:58 p.m. West
Thu. Feb. 8 6:59 p.m. 7:59 p.m. West
Fri. Feb. 9 7:00 p.m. 8:00 p.m. West
Sat. Feb. 10 7:01 p.m. 8:01 p.m. West
Sun. Feb. 11 7:02 p.m. 8:02 p.m. West
Mon. Feb. 12 7:04 p.m. 8:04 p.m. West
Tue. Feb. 13 7:05 p.m. 8:05 p.m. West
Wed. Feb. 14 7:06 p.m. 8:06 p.m. West
Thu. Feb. 15 7:07 p.m. 8:07 p.m. West
Fri. Feb. 16 7:08 p.m. 8:08 p.m. West
Sat. Mar. 3 7:27 p.m. 7:59 p.m. West
Sun. Mar. 4 7:28 p.m. 8:28 p.m. West
Mon. Mar. 5 7:29 p.m. 8:29 p.m. West
Tue. Mar. 6 7:30 p.m. 8:30 p.m. West
Wed. Mar. 7 7:32 p.m. 8:32 p.m. West
Thu. Mar. 8 7:33 p.m. 8:33 p.m. West
Fri. Mar. 9 7:34 p.m. 8:34 p.m. West
Sat. Mar. 10 7:35 p.m. 8:35 p.m. West
Sun. Mar. 11 8:37 p.m. 9:37 p.m. West
Mon. Mar. 12 8:38 p.m. 9:38 p.m. West
Tue. Mar. 13 8:39 p.m. 9:39 p.m. West
Wed. Mar. 14 8:41 p.m. 9:41 p.m. West
Thu. Mar. 15 8:42 p.m. 9:42 p.m. West
Fri. Mar. 16 8:43 p.m. 9:43 p.m. West
Sat. Mar. 17 8:44 p.m. 9:44 p.m. West
Sun. Mar. 18 8:46 p.m. 9:46 p.m. West
Mon. Mar. 19 9:38 p.m. 9:47 p.m. West
Mon. Apr. 2 9:06 p.m. 9:56 p.m. West
Tue. Apr. 3 9:08 p.m. 10:08 p.m. West
Wed. Apr. 4 9:09 p.m. 10:09 p.m. West
Thu. Apr. 5 9:11 p.m. 10:11 p.m. West
Fri. Apr. 6 9:12 p.m. 10:12 p.m. West
Sat. Apr. 7 9:14 p.m. 10:14 p.m. West
Sun. Apr. 8 9:15 p.m. 10:15 p.m. West
Mon. Apr. 9 9:17 p.m. 10:17 p.m. West
Tue. Apr. 10 9:18 p.m. 10:18 p.m. West
Wed. Apr. 11 9:20 p.m. 10:20 p.m. West
Thu. Apr. 12 9:21 p.m. 10:21 p.m. West
Fri. Apr. 13 9:23 p.m. 10:23 p.m. West
Sat. Apr. 14 9:25 p.m. 10:25 p.m. West
Sun. Apr. 15 9:26 p.m. 10:26 p.m. West
Mon. Apr. 16 9:28 p.m. 10:28 p.m. West
Tue. Apr. 17 9:43 p.m. 10:29 p.m. West
Thu. Aug. 9 3:08 a.m. 3:44 a.m. East
Fri. Aug. 10 3:09 a.m. 4:09 a.m. East
Sat. Aug. 11 3:11 a.m. 4:11 a.m. East
Sun. Aug. 12 3:13 a.m. 4:13 a.m. East
Mon. Aug. 13 3:14 a.m. 4:14 a.m. East
Tue. Aug. 14 3:16 a.m. 4:16 a.m. East
Wed. Aug. 15 3:18 a.m. 4:18 a.m. East
Thu. Aug. 16 3:19 a.m. 4:19 a.m. East
Fri. Aug. 17 3:21 a.m. 4:21 a.m. East
Sat. Aug. 18 3:22 a.m. 4:22 a.m. East
Sun. Aug. 19 3:24 a.m. 4:24 a.m. East
Mon. Aug. 20 3:26 a.m. 4:26 a.m. East
Tue. Aug. 21 3:27 a.m. 4:27 a.m. East
Wed. Aug. 22 3:29 a.m. 4:29 a.m. East
Thu. Aug. 23 3:30 a.m. 4:30 a.m. East
Fri. Aug. 24 4:20 a.m. 4:32 a.m. East
Sat. Sep. 8 3:54 a.m. 4:54 a.m. East
Sun. Sep. 9 3:55 a.m. 4:55 a.m. East
Mon. Sep. 10 3:57 a.m. 4:57 a.m. East
Tue. Sep. 11 3:58 a.m. 4:58 a.m. East
Wed. Sep. 12 3:59 a.m. 4:59 a.m. East
Thu. Sep. 13 4:01 a.m. 5:01 a.m. East
Fri. Sep. 14 4:02 a.m. 5:02 a.m. East
Sat. Sep. 15 4:03 a.m. 5:03 a.m. East
Sun. Sep. 16 4:05 a.m. 5:05 a.m. East
Mon. Sep. 17 4:06 a.m. 5:06 a.m. East
Tue. Sep. 18 4:07 a.m. 5:07 a.m. East
Wed. Sep. 19 4:09 a.m. 5:09 a.m. East
Thu. Sep. 20 4:10 a.m. 5:10 a.m. East
Fri. Sep. 21 4:11 a.m. 5:11 a.m. East
Sat. Sep. 22 4:12 a.m. 5:12 a.m. East
Sun. Sep. 23 5:07 a.m. 5:14 a.m. East
Sun. Oct. 7 4:30 a.m. 5:04 a.m. East
Mon. Oct. 8 4:32 a.m. 5:32 a.m. East
Tue. Oct. 9 4:33 a.m. 5:33 a.m. East
Wed. Oct. 10 4:34 a.m. 5:34 a.m. East
Thu. Oct. 11 4:35 a.m. 5:35 a.m. East
Fri. Oct. 12 4:36 a.m. 5:36 a.m. East
Sat. Oct. 13 4:37 a.m. 5:37 a.m. East
Sun. Oct. 14 4:39 a.m. 5:39 a.m. East
Mon. Oct. 15 4:40 a.m. 5:40 a.m. East
Tue. Oct. 16 4:41 a.m. 5:41 a.m. East
Wed. Oct. 17 4:42 a.m. 5:42 a.m. East
Thu. Oct. 18 4:43 a.m. 5:43 a.m. East
Fri. Oct. 19 4:44 a.m. 5:44 a.m. East
Sat. Oct. 20 4:45 a.m. 5:45 a.m. East
Sun. Oct. 21 4:47 a.m. 5:47 a.m. East
Mon. Oct. 22 4:57 a.m. 5:48 a.m. East

On the February, March, and April evenings listed above, you will see a broad, faint band of light extending upwards from the western horizon, sloping a little to the left, and reaching nearly halfway to the top of the sky.

On the August, September, and October mornings listed above, you will see a broad, faint band of light extending upwards from the eastern horizon, sloping a little to the right, and reaching nearly halfway to the top of the sky.

It is essential that your view is not spoiled by nearby streetlights, parking lot lights, or dusk-to-damn insecurity lights, nor any city to the west (Feb-Apr) or east (Aug-Oct).  Give your eyes a few minutes to adjust to the darkness.  Slowly sweeping your eyes back and forth from southwest to northwest (Feb-Apr) or northeast to southeast (Aug-Oct) will help you spot the zodiacal light band.  Once spotted, you should be able to see it without moving your head.

On the February, March, and April evenings listed above, the zodiacal light is best seen right at the end of evening twilight, and remains visible for an hour or so after that.

On the August, September, and October mornings listed above, the zodiacal light is best seen about an hour or so before the beginning of morning twilight, right up to the beginning of morning twilight.


10 thoughts on “Zodiacal Light 2018”

  1. It is nice to see such a prediction about Zodiacal lights.
    Can you please calculate the local times when such lights will be visible from places at the Tropic of Cancer and at Equator?
    Can you share the formula for such calculations?

  2. Dear Dr. Ahmed,

    The best times to see the zodiacal light is when the ecliptic is most nearly perpendicular to the horizon, right after the end of astronomical twilight (Sun altitude -18°) in the evening, and right before the beginning of astronomical twilight in the morning. The following diagrams will show you the angle the ecliptic makes with the horizon on the 15th of each month of the year for latitudes 43°N (Dodgeville, WI), 23°26’12.8″N (Tropic of Cancer), and 0° (The Equator).

    Zodiacal Light – A.M.

    Zodiacal Light – P.M.

    I was surprised to find that the best mid-months for morning zodiacal light is actually September, October, and November (and not so much August) at both latitudes 43°N and 23°N, though you can see the ecliptic makes a much more perpendicular angle with the horizon at 23°N. So, along the Tropic of Cancer, the zodiacal light will be easier to see in other months, too. When I lived in Alpine, Texas (latitude 30°N), I indeed noticed that the zodiacal light was more impressive than my experiences seeing it further north.

    Similarly, the best mid-months for evening zodiacal light is actually January, February, and March (and not so much April) at both latitudes 43°N and 23°N. Again, the ecliptic makes a steeper angle with the horizon at the Tropic of Cancer.

    The situation at the Equator is a bit different. January and July are the best months for morning zodiacal light there, and May-June and November-December for the evening zodiacal light.

    The other factor to consider (besides minimal to no light pollution) for picking zodiacal light viewing times is no lunar interference. Any good planetarium software will allow you to find astronomical twilight for any date when the Moon isn’t above the horizon. I used Voyager 4.5. If you want to calculate the times when the Sun is 18° below the horizon and the Moon is below the horizon, there are several good books by Jean Meeus (and others) that show you how. I myself wrote such a program in Applesoft BASIC on an Apple ][+ computer back in 1981, and I have a version of it today written in SAS that I use to generate my Dark Skies page each month.

    In conclusion, I now realize that the best months for observing the zodiacal light this year perhaps should have excluded April and included January, and excluded August and included November. Of course, this will vary slightly from year to year depending on what time of the month presents moonless skies. When I publish Zodiacal Light 2019 next January, I will do a more careful analysis to make sure I get it right!

    1. Dear Mr.Oesper,
      I am grateful to you for your prompt reply. I found your reply very informative. Allow me to ask you as to what does the abbreviation ST stand for in you diagrams? Does LDT stand for Local Daylight Time? You have shown three lines for each date for three different times. What is the significance of the times chosen? Do these times correspond to the beginning, middle and end of the appearance of Zodiacal light? How many degrees below the horizon is sun at these times? Does the Zodiacal light disappear and sky becomes dark again before the appearance of astronomical twilight at 18 degrees, or because of the relatively brighter astronomical twilight, zodiacal light ceases to be visible?
      I do have Stellarium software on my computer but it does not show zodiacal lights. I will try to download Voyager software you suggested but at 86 years of age I take time doing things.
      Again let me express my gratitude to you for reply.
      With best regards,
      Dr. Amin Uddin Ahmed

      1. Greetings Dr. Ahmed,

        ST is a label in Voyager that should actually be LST which is local sidereal time. It is the right ascension of objects on the celestial meridian at that moment in time for that location.

        LDT does indeed stand for Local Daylight Time, and LMT stands for Local Mean Time for the times of the year when daylight saving time is not in effect.

        The times chosen are the moment when astronomical twilight begins in the a.m. diagrams, and when astronomical twilight ends in the p.m. diagrams. In both cases, the Sun is 18 degrees below the horizon at this moment.

        The zodiacal light is best seen right when the Sun is 18 degrees below the horizon. In my original article, I have arbitrarily chosen a period of one hour before astronomical twilight begins to the beginning of astronomical twilight as the best time to observe the morning zodiacal light. Likewise, from the end of astronomical twilight until one hour later for the evening zodiacal light. Incidentally, astronomical twilight is defined to be when the Sun is between 18 and 12 degrees below the (geometric) horizon. When the Sun is less than 18 degrees below the horizon twilight washes out the zodiacal light. So you are correct in stating that the zodiacal light ceases to be visible because of the relatively brighter astronomical twilight.

        Thank you for your questions!

    2. In continuation of my reply to you about an hour ago I would like to add that using MoonCalc6 softwares, the altitude values for Dodgeville for September 15th for 4:03 and 5:03 am, came to be -35.701 and 27.542 respectively. Any comment on correctness of these values?

      1. With the Voyager 4.5 software, on September 15, 2018 I find a Sun altitude of -35.843° at 3:03 a.m. CDT, -27.705° at 4:03 a.m. CDT and –18.069° at 5:03 a.m. CDT at Dodgeville.

        1. Thank you once again for your informative reply.
          I forgot to mention that the altitudes that I calculated using MoonCalc6 software were those of sun and not of moon. I wonder if I arrived at the right values. I wanted to send you screenshots of MoonCalc6 results but didn’t know how to incorporate those in the reply box. (My usual help, my grand son, is away these days). If I knew your email I could have sent the attachment.
          Incidentally, I do have Starwalk software on my mobile as well as iPad and this program also displays ecliptic. Your reply about the ecliptic angle gave me the idea of using Starwalk. Thanks once again. With regards.

        2. I wonder as to how long ( minutes or hours) the Zodiacal light was visible to you before the astronomical twilight began?

          1. The visibility of the zodiacal light is always best right before the beginning of astronomical twilight (in the a.m.) or right after the end of astronomical twilight (in the p.m.). The zodiacal dust band is most dense and brightest closest to the Sun, and at these moments you are seeing the closest part of the zodiacal band to the Sun without twilight interference. When the Sun is more than 18° below the horizon, you can still see the zodiacal light, but you are seeing the part of it that is further away from the Sun, so it will be fainter. The interval of visibility of the zodiacal light depends on the transparency of the atmosphere, the darkness of the sky (i.e. freedom from light pollution), and the angle the ecliptic makes with the horizon—the more perpendicular the better—and that depends on both your latitude and the time of year. I have rather arbitrarily chosen (but based on my own experience) one hour before twilight begins as the best time to begin looking for the zodiacal light in the morning, and you should normally be able to see the zodiacal light in the evening until at least one hour after the end of astronomical twilight. However, in very dark locations and under ideal atmospheric conditions it is possible to detect the zodiacal light crossing the entire sky (along the ecliptic) and even the faint glowing region 180° from the Sun called the gegenschein, which I have only seen a couple of times.

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