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Mars in daylight, no telescope needed

You won’t be the first to spot the Red Planet when the Sun’s up.
OMearaStephen
The naked-eye appearance of Mars has captivated humanity since the emergence of human thought. That’s why I found the following comment by E.B. Knobel (in a letter to the journal The Observatory, dated February 8, 1910) strange: “I do not think there is anything remarkable in the ‘Naked-eye Observation of Mars during Sunlight’ [mentioned] in the current issue.” As proof, Knobel submitted two drawings showing Mars in June 1873 (then 15" in diameter) “when the Sun was shining brightly upon me,” adding that “it was bright enough to have been easily detected by even the most casual observer with the unaided eye.”

Then I read the Editors’ comment below: “We regret that we are unable to reproduce Mr. Knobel’s sketches of Mars . . . which show prominent surface details quite plainly.”

OK, I have to admit that seeing Mars with the unaided eye in daylight is not exceptionally “remarkable,” especially during a perihelic opposition, like the one we just had last July. But it is fun to try and exciting if you succeed. On the other hand, it is in no way as easy as Knobel makes it out to be. Nor would the planet, by any stretch of the imagination, be visible to a casual gaze — especially a half-hour prior to sunset.

MarsinJuly
The author spotted Mars a couple of minutes before sunrise July 22, 2018, within the Belt of Venus and Earth’s shadow.
Both images: Stephen James O’Meara
Casual vs. dedicated efforts

My first attempts at seeing Mars in daylight were somewhat casual. On the morning of July 22, just five days from opposition, I saw Mars mingling with the Belt of Venus in the west, about 10 minutes before sunrise. At the time, Mars was nearly superlative: 100 percent illuminated, at 171° elongation from the Sun, 24" in diameter, 0.39 astronomical unit (AU) from Earth, and shining at magnitude –2.7. Easy, right? Actually, no.

While Mars was apparent five minutes from sunrise (easy enough for me to take photos of it), I lost sight of it as sunrise approached simply because I looked away from it for about 30 seconds! Try as I might, I just couldn’t pull it out of the sky background after that.

But there is good news. On the same day, Scott Harrington of Evening Shade, Arkansas, was able to follow Mars for 1 minute 30 seconds after sunrise. For him, Mars was only 3.2° high and also in the dark purple-blue part of the Belt of Venus.

My first success came September 11 when Mars was 48° above the horizon, 92 percent illuminated, at 131° elongation from the Sun, 19" in diameter, 0.49 AU from Earth, and shining at magnitude –1.8. What’s more, the skies were not as transparent as they were in July. Clearly, the greater altitude was a major factor.

After spying Mars, I lined up the planet with some branches, then moved a chair to that prime viewing spot. The next afternoon, I sat in the chair and found Mars 30 minutes before sunset through binoculars, and 16 minutes before sunset with my unaided eyes.

RedPlanetbluesky
The Red Planet was easy to pick out in a clear blue sky 20 minutes before sunset.
Meanwhile, in Tomball, Texas, 17-year-old Lauren Herrington challenged herself to see Mars with the naked eye, and after several attempts, she succeeded September 17. That day, sunset occurred at 7:25 p.m. Lauren first found Mars through binoculars around 6:50 p.m. So, she lined Mars up with a tree and started searching naked-eye. “Talk about blue field entoptic phenomenon!” she shared. “The blue field phenomenon really got in my way, with shimmery vision and little bright points everywhere. So, with my vision dense with all that, picking out Mars was a real challenge.”

Persisting, Lauren suddenly got the idea to move her head back and forth and see if motion would pull it out, “like tapping a scope,” she said. She was successful, as “little Mars became immediately apparent! It wasn’t quite the same as how motion helps in the eyepiece, but it made Mars move differently than the blue field phenomenon and stick out like a sore thumb among the many other tiny points of light in my vision. It was 7:03 p.m., and though it was faint, I bet I could see it earlier if I keep trying, now that I know about the trick of swaying back and forth.”

Harrington had a string of success in sighting Mars (magnitude –1.6) with his naked eyes, also beginning September 18, when he saw it exactly seven minutes before sunset. As with me and Lauren, Harrington used the first night to line Mars up with a tree after sunset, then marked his location and returned to it the next night. His record naked-eye sighting of the Red Planet was 17 minutes before sunset September 19.

If you’ve had similar success, share your views with me at sjomeara31@gmail.com.

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