Beginning in late November during the waning phases of the Moon, and then again in late December, you can investigate the possibility of a curious optical phenomenon. It involves a bright planet passing by a large and diffuse star cluster visible with the naked eye.
On the evening of June 13, 2023, I went out as twilight faded to observe the conjunction of Venus with the Beehive open star cluster (M44). Shining brilliantly at magnitude –4.2, Venus sailed within 1° of the cluster. Under a dark sky, the Beehive appears to the unaided eye as a diffuse, 4th-magnitude glow spanning 95′ of sky.
When darkness fell, I could see both Venus and the Beehive with direct vision. Unsurprisingly, when I looked at them with averted vision, the Beehive appeared to swell in brightness (as its light fell onto the night-sensitive rod cells in my eyes), while that of Venus diminished slightly (as its bright light no longer stimulated the day-sensitive cone cells). The feeling was one of transference, as if Venus had lent the Beehive some of its light. The view made Venus appear like a comic-book superhero — a bright gleaming superstar with a diffuse cape blowing in the wind.
Then, I noticed a most curious phenomenon: If I extended a finger at arm’s length and blocked the light of Venus, the Beehive appeared to dim! It didn’t matter if I was using averted vision or direct vision. The result remained constant. Again, the very presence of Venus appeared to enhance the glory of the Beehive.
The reason may simply be one of proximity. Anyone who has ever looked for Venus in the daytime knows how difficult it can be to fix one’s eyes on the planet in a vast blue sky. They’ll also know how easily Venus appears when the Moon is in conjunction with it. The simple explanation for this is that the proximity of the Moon helps the eye lock onto the position of the planet, making it appear brighter and more motionless than if the Moon weren’t there.
This point was made clear with another planet on July 14, 2023. I observed a daytime conjunction of Jupiter with the waning, 14-percent crescent Moon, allowing me to clearly see Jupiter shining at magnitude –2.1 with the unaided eye until 10 minutes after sunrise.
Now, the question that remains is whether the Beehive will receive the same glow up from Mars.
As 2024 draws to a close, Mars will be within 2° of M44 and appear nearly stationary, especially toward the end of November, as the planet starts its retrograde motion Dec. 7. The planet will also be approaching Earth, brightening from magnitude –0.5 in late November to magnitude –1.0 in late December. That’s about 16 times dimmer than what Venus’ magnitude was in June 2023. So while Mars will not be as bright or come as close to M44 as Venus did in June 2023, the conjunction will be worth investigating.
Prior to my Venus observation, Mars was conjunct with the Beehive on the evenings of June 1 and 2, 2023. But the Red Planet was shining dimly at around magnitude 2 — more than 600 times fainter than Venus. Unfortunately, I was not able to observe that passage, so I cannot comment on the effect during that event.
However, on the morning of June 6, 2024, a 1st-magnitude Saturn was positioned only about 2.5° from the visual grouping of Psi1 (ψ1), Psi2, and Psi3 Aquarii — three 4th- and 5th-magnitude stars in an area of sky only 1° apart. With a quick glance, these stars appear fuzzy, especially with averted vision, but with direct vision, they resolve. I also experimented with Saturn and the appearance of the stars, and there the effect surfaced: The presence of the planet enhanced the visibility of the three stars.
Will the presence of a bright Mars enhance the Beehive’s visibility? Will the warm color of the planet diminish the visual effect? I would like to know what, if anything, you experience. Send reports to sjomeara31@gmail.com.
