By David H. Levy
The wonderful visit of Olbers’s Comet.
On Tuesday, June 4, 2024, David Rossetter and I headed out for our monthly observing session at the Chirichuaha astronomy complex, the dark site of the Tucson Amateur Astronomy Association. In addition to the normal 2 hours of comet searching I did that evening, David located Comet Tsuchinshan–ATLAS, a bright 10th magnitude comet with a pretty dust tail. I wish I had paid more attention that evening to the other comets that would be visible that night. If I had been more careful, I would have noticed that Comet Olbers was returning for the first time since 1956. There is no way I would have seen this comet then since I was only eight years old at the time. Since it was already pretty bright, I tried to locate it from my observatory on the following Friday evening. But the comet’s position low in the northwest made that impossible. On Saturday evening I tried it again from my front porch which does have an excellent view to the northwest, but is looking over Tucson. I used a brand-new telescope, a 6-inch diameter telescope from the Sky-Watcher company. This new telescope, presented to me by Dean Koenig of Starizona, was destined to go to Robin Chapell. Robin has been cleaning my home for many years, first for Wendee and me, and more recently just me, and a few weeks ago she expressed an interest in getting a telescope. To test the new telescope, I tried to use it to find Comet Olbers. I didn’t catch it Saturday or Sunday evening, although I might have gone right over it Sunday without spotting it.
On Monday, June 10, I drove to David and Pamela Rossetter’s home to find him setting up Archimedes, his 12-inch reflector, in his driveway, which had an excellent view to the northwest except for a Palo Verde tree. After carefully aligning the 12-inch telescope on Polaris, then Spica, then Pollux and finally Castor, he put in the comet’s position and moved the telescope. Lo, the comet was in the middle of the tree! David looked anyway, and saw two faint stars in the telescope’s field.
Toward the left of one of the stars, he detected a faint fuzzy spot. Then it was my turn. Immediately I also detected the fuzzy spot. It was real. For the first time in both our lives, we saw Comet Olbers. Pam joined us for a brief visit.
Heinrich Olbers discovered this comet on March 6, 1815. The comet is named for him as 13P/Olbers. But the comet is not what he is famous for. His magnum opus is Olbers’ Paradox. In 1823 he proposed that with stars spread out to infinity in the sky, there should be no point in the sky that does not fall upon the surface of a distant star. Olbers then suggested that because of this, every inch of sky should be as bright as the Sun. The Nobel prize-winning physicist George Wald went further a fee decades ago, adding that the sky should be so bright that life on Earth would be impossible. “But the night sky is dark; therefore, life here is possible.”
One would expect that some famous scientist was the first person to resolve Olbers’s Paradox. Not quite. An American writer famous for his poetry and short stories, Edgar Allan Poe’s is one of the truly great American writers. His poem The Raven, written in 1845, is one of the World’s most famous pieces of literature, brought to life when two ravens adopted Gene and Carolyn Shoemaker, who dutifully named them Never and More:
Presently my soul grew stronger; hesitating then no longer,
“Sir,” said I, “or Madam, truly your forgiveness I implore;
But the fact is I was napping, and so gently you came rapping,
And so faintly you came tapping, tapping at my chamber door,
That I scarce was sure I heard you”—here I opened wide the door;—
Darkness there, and nothing more.Deep into that darkness peering, long I stood there wondering, fearing,
Doubting, dreaming dreams no mortal ever dared to dream before;
But the silence was unbroken, and the darkness gave no token,
And the only word there spoken was the whispered word, “Lenore!”
This I whispered, and an echo murmured back the word, “Lenore!”
Merely this and nothing more.…
Then this ebony bird beguiling my sad fancy into smiling,
By the grave and stern decorum of the countenance it wore,
“Though thy crest be shorn and shaven, thou,” I said, “art sure no craven,
Ghastly grim and ancient Raven wandering from the Nightly shore,—Tell me what thy lordly name is on the Night’s Plutonian shore!”
Quoth the Raven, “Nevermore.”
As delightful as The Raven is, and as often as the word darkness appears in it, the poem does not explain why the night sky is dark. But three years later, Poe’s final major piece of writing, “Eureka”, solves the paradox perfectly:
“Were the succession of stars endless, then the background of the sky would present us an uniform luminosity, like that displayed by the Galaxy—since there could be absolutely no point, in all that background, at which would not exist a star. The only mode, therefore, in which, under such a state of affairs, we could comprehend the voids which our telescopes find in innumerable directions, would be by supposing the distance of the invisible background so immense that no ray from it has yet been able to reach us at all.”
That this is correct was not really confirmed until Edwin Hubble described the expanding universe around 1929, and these observations were confirmed by modern work by the Hubble and Webb Space Telescopes.
It is a simple, beautiful, and even loving sentence. “The night sky is dark; therefore life is possible on Earth.” And on one lovely evening during that life, I got to enjoy the little comet he found, ands which was paying us a welcoming visit from the outer reaches of the solar system where our lives transpire.
