The moment she saw the sun, something inside Julie McKelvey changed.

She was hanging from a rope on the side of Mt. Everest, four hours from the summit. The night was frozen, the slope some 60 degrees steep, the oxygen thin as she ascended to the highest point on earth. In the dark, she felt the fear and power of the mountain. She focused on exactly where to put her foot, her hand, alongside her fellow climbers.

Then, peripherally to her right, she saw an orange flash.

“I see this sunrise that I will never forget as long as I live,” she reflected. “The colors — it is just red, and then it is orange, and then it is yellow, and then the blue is coming. It was so incredibly spiritual for me, and beautiful.”

Ms. McKelvey, a mother and executive from central Pennsylvania, searched for words to capture the emotion of that moment. She felt so connected with something so much bigger than herself, something that she believed loved her. “The whole thing is very awe-ful. A-w-e,” she said, meaning full of awe.

On Monday, millions of people are hoping for their own sun-powered experience of awe. A total solar eclipse will sweep across North America, from Mazatlán up through Indiana to Newfoundland. More than 30 million people live in the path of totality, where for a few brief minutes the moon will entirely block out the sun, and darkness will swallow the light of day. A halo will glow white behind the moon, the sun’s corona.

Amid the rush to purchase eclipse glasses to protect one’s eyes and to check if clouds will disrupt the view, a deeper human experience is unfolding. The eclipse taps into a primal emotion, and evokes for many a sort of mystical moment and childlike wonder, as awareness of the celestial encompasses the earth. It is a present reminder to everyone, on the same day, that life can be magical.

For a nation pulled apart by every manner of division, the eclipse and the awe it inspires offers a moment of unity, if brief. It is a reminder of the collective experience of being alive, of the dance between spirituality and science, and the sheer astonishment at being part of the greater story of things.

“Astronomical phenomena have probably likely always been a source of awe and fear, from ever since Homo sapiens could stand upright and look at the night sky,” said Priyamvada Natarajan, a professor of astronomy at Yale University. “In these really turbulent times, these experiences of collective awe are probably extremely helpful in showing us to transcend the day-to-day noise and chaos of our lives, and of nations’ lives.”

In ancient days, communities in India believed an eclipse was a demon swallowing the sun, Ms. Natarajan said. But now an eclipse is an opportunity to pay homage to the explanatory power of science. And in modern secular society, it offers a sense of belonging, a collective moment like the religious expression of prayer and gratitude. “The question is about transcendence,” she said.

Brother Guy Consolmagno, the director of the Vatican Observatory, the pope’s official astronomical institute that dates back to the Renaissance, hopes to see the eclipse from Indiana through his small Celestron binoculars.

He remembered the feeling of awe he felt returning from Antarctica and being able to see the Eta Carinae nebula for the first time. And the moment in the lab studying meteorites when he saw a pattern in the data that he had never before seen.

“The universe is elegant, it is beautiful, and it’s beautiful in a way that surprises you,” Brother Consolmagno said. “Maybe it’s a sense of what God is like.”

If you had no idea the eclipse was happening, it would be terrifying, he said. But when you can predict down to the second when it starts, when it will be at its maximum and when it will be finished, “it becomes a delight that I can be so in tune with the universe,” he said. “That, to me, crystallizes what it is to be a scientist, to be clever enough to predict, but then open to being surprised.”

The English word “awe” comes from early Scandinavian around the 12th century, meaning “fear, terror, dread,” at times mixed with reverence in relation to God or the divine, according to lexicographers at the Oxford English Dictionary. By the time of Shakespeare, the word was used in reference to great earthly rulers, the sense of fear mixed with reverence and wonder.

But by the 18th century, in the Age of Enlightenment, which emphasized reason and science, awe shifted from a religious context to the power and beauty of the natural world.

The semantics of the word are linked to fear, but awe is actually a positive emotion, said Dacher Keltner, a psychologist at the University of California, Berkeley, who wrote a book on awe.

“Awe is an emotion when you encounter things you don’t understand,” he said. “Wonder follows experiences of awe because you want to explain the mystery of it.”

The sense of the transcendence in religion is not that different from what he sees as a scientist in encountering evolution. “We are probably talking about the same experience,” Mr. Keltner said.

Today, half of American adults report feelings of loneliness, and technology disconnects people from lived physicality of the human experience. Virtual realities promised an “awesome” future but have not delivered, Mr. Keltner said, and people are hungry for something more, for transcendent emotions, for a sense of loss of self.

“There is something profound about sharing our awareness of meaningful events,” he said.

Ancient Sanskrit texts like the Bhagavad Gita mention adbhuta, describing an expression of awe and wonder that is scary, said Deepak Sarma, professor of Indian religions and philosophy at Case Western Reserve University. Even though adbhuta has something fearful in it, it is beautiful.

“Maybe something that is wonderful ought to be something feared,” said Professor Sarma, who uses the pronouns they and them. The eclipse will pass right overhead the professor’s home, and they plan to go outside and invoke various Hindu prayers and Wiccan rituals, with their partner and cat.

The eclipse is egalitarian, available to everyone, and not just humans. “All sentient creatures are going to experience this, even not sentient creatures,” they said, noting that even the stones on the ground will cool when the sun disappears.

During the 2017 total eclipse, Daniel Beverly, a postdoctoral research fellow at Indiana University, measured what happened to individual sagebrush leaves when the sun went dark. The plant showed biochemical signs of stress, as photosynthesis stopped and carbon uptake slowed, he said.

This time, he has experiments set up to measure the impact on an entire forest of sugar maples, white oaks, tulip poplars and sassafras. It is a rare chance to learn how an eclipse affects not just one individual, but an entire ecosystem, Mr. Beverly said.

“We never get to make an entire forest go dark for four minutes,” he said. “It is an opportunity to connect dots we don’t normally get to.”

Awe is found not just in the skies. The eclipse will not pass over Arizona, but at the bottom of the Grand Canyon, Sarah Haas, deputy chief of science and resource management for the national park, is filled with awe looking up from the Colorado River.

“You are getting a snapshot from the bottom of the earth, looking back, the colors and the sky, from the river,” she said. “There is something very connecting to the soul about that experience.”

Away from technology and cellphone service, there is a sense of being part of the story of the canyon, carved over millions of years. Ms. Haas feels it in the smell of being in the riparian zone at the river’s edge, in the sight of how the red boulders have landed over time and in the surprises of water coming up from springs.

“The river is this living entity, that is moving and adjusting over time, and you are just on the ride of that day’s experience of the river and the rocks and the rapids,” she said.

When a group leaves to travel down the river with a group, it quickly becomes self-reliant, and strangers become family, dependent on one another for survival, Ms. Haas said.

“You have to keep in mind there are things that could hurt you, or things the canyon needs to do to evolve and to grow that you have to be aware of, like flash flooding or rockfalls,” she said.

A year after she climbed Mt. Everest, Ms. McKelvey is still unpacking the emotion of the enormity of the mountain. She recently finished another summit, becoming one of few women in the world to top the highest peaks on all seven continents.

Like the experience of the eclipse’s totality, which lasts only a few minutes, her time at the summit of Everest was brief, maybe just 20 minutes, she said. Perhaps that may be part of the revelation.

“What I am realizing is, it was the process the whole time. It was never about the top of any of the mountains,” Ms. McKelvey said.

Most awe-inspiring of all was simply being present to the moment, both to the world and to those around her as they suffered together in the cold and cheered each another on, she said.

“That is where the magic is,” she said. “I’m not living in the past, I’m not living in the future … I am just here.”