The Three Secrets of Fátima (Portuguese: Os Três Segredos de Fátima) are a series of apocalyptic visions and prophecies 

These were reportedly given to three young Portuguese  Lúcia Santos and her cousins Jacinta and Francisco Marto, by a Marian apparition, starting on 13 May 1917.

The three children claimed to have been visited by the Virgin Mary six times between May and October 1917. The apparition is now popularly known as Our Lady of Fátima.

According to Lúcia, around noon on 13 July 1917, the Virgin Mary entrusted the children with three secrets. Two of the secrets were revealed in 1941 in a document written by Lúcia, at the request of José Alves Correia da Silva, Bishop of Leiria, to assist with the publication of a new edition of a book on Jacinta.[1] When asked by the Bishop in 1943 to reveal the third secret, Lúcia struggled for a short period, being “not yet convinced that God had clearly authorized her to act”.[1] However, in October 1943 the Bishop ordered her to put it in writing.[1] Lúcia then wrote the secret down and sealed it in an envelope not to be opened until 1960, when “it will appear clearer”.[1] The text of the third secret was officially released by Pope John Paul II in 2000. Some claim that it was not the entire secret revealed by Lúcia, despite repeated assertions from the Vatican to the contrary.

According to various Catholic interpretations, the three secrets involve Hell, World War I and World War II, and 20th-century persecutions of Christians.

A meticulous synthesis of history, science, and anthropology, ‘Heavenly Lights’ establishes that the Fátima Incident of 1917 involved not “Marian apparitions” — as is conventionally believed — but rather, a series of close encounters with alien beings

Different people saw different things. Some present saw nothing, & various theories, which is a fancy way to say guesses have been proposed,

In a 1960 interview by John Haffert of Dominic Reis, who was just 17 when he went to the Cova da Iria[Fatima] on October 13, 1917, with his mother and father, Dominic testified:

“On the side was a big tree, and little small trees around, and the children were there. And now it was raining harder. There was a good three inches of water where I stood, and mud on the ground. I was soaking wet…and then around noontime, the sun started breaking…we can see the sun…Now it was raining, just like you open a faucet at your house. Rain!

The best evidence of the actuality of the miracle is in the incident of the simultaneous drying of the clothes of the people int eh Cova da Iria, as well as the very ground upon which they were standing. Dominic, who was about a hundred feet from the tree of the apparitions on October 13, 1917, tells us what happened next:

“As soon as the sun went back in the right place the wind started to blow real hard, but the trees didn’t move at all. The wind was blow, blow and in a few minutes the ground was dry. Even our clothes had dried. We were walking here and there and our clothes were dry and looked as though they had just come from the laundry. I believed. I thought, ‘Either I’m out of my mind or this was a miracle. A real miracle.’”

https://www.bluearmy.com/fatimas-solar-miracle/

The story of a famous miracle in Fátima, Portugal, began in May 1917, when three children (ages 7, 9, and 10) claimed to have encountered the Virgin Mary on their way home from tending a flock of sheep. The oldest girl, Lucia, was the only one to speak to her, and Mary told the children that she would reappear to them on the thirteenth day of the next six months. She then vanished.

The children soon told their parents, and while some in the village didn’t believe their tale, others did — and told more people. As the weeks and months passed, more and more of the faithful made pilgrimages to Fátima, where the children claimed to receive Mary’s visits.

Still no one else saw the Virgin Mary; instead, the gathered adults would stand riveted as Lucia took the lead and began to describe her visions.

The three Fátima children: Lucia Santos, 10, in the middle; with her cousins, Jacinta, 7, and Francisco Marto, 9. (Image credit: Public domain)

It was Mary’s final appearance, on Oct. 13, 1917, that became the most famous. In his book “Looking for a Miracle,” Joe Nickell states that “an estimated 70,000 people were in attendance at the site, anticipating the Virgin’s final visit and with many fully expecting that she would work a great miracle. As before, the figure appeared, and again only to the children. Identifying herself as ‘the Lady of the Rosary,’ she urged repentance and the building of a chapel at the site. After predicting an end to [World War I] and giving the children certain undisclosed visions, the lady lifted her hands to the sky. Thereupon Lucia exclaimed, ‘The sun!’

As everyone gazed upward, and saw that a silvery disc had emerged from behind clouds, they experienced what is known [as] a ‘sun miracle’.”