Otherwise we do not have a copy of the "Book of Jashar" (the Book of the Just) that dates to the Iron Age.
The events described in Joshua 10 date to the period of the Conquest that falls somewhere in the Late Bronze Age - Early Iron Age horizon. (Modern Biblical scholars are working hard to find out if, how and when the events described in the Book of Joshua, Judges and other Deuteronomist history took place.)
This is the only fragment that has survived from the ancient source quoted in Joshua 10
On the day the Lord gave the Amorites over to Israel, Joshua said to the Lord in the presence of Israel:
“Sun, stand still over Gibeon,Just before this momentous event Book of Joshua describes the victorious battle that rolled down the Valley of Beth Horon. [Today the geologically ancient river valley is one of the major highway routes from Tel Aviv to Jerusalem.] The Hebrews felt how even their God was participating in the war and in the killing of the enemy.
and you, moon, over the Valley of Aijalon. ”
So the sun stood still,
and the moon stopped,
till the nation avenged itself on its enemies,
as it is written in the Book of Jashar.
Joshua 10:12-13 NIV
After an all-night march from Gilgal, Joshua took them by surprise. The Lord threw them into confusion before Israel, so Joshua and the Israelites defeated them completely at Gibeon. Israel pursued them along the road going up to Beth Horon and cut them down all the way to Azekah and Makkedah. As they fled before Israel on the road down from Beth Horon to Azekah, the Lord hurled large hailstones down on them, and more of them died from the hail than were killed by the swords of the Israelites.NIV helps us with the translation "hailstones" as the Hebrew text has the word "stones".
Joshua 10:9-11 NIV
It is interesting that something in the weather conditions in the generic area of the Valley of Ayalon are such that there have been also in recent years in the exact same region very heavy rain of large hailstones as reported in Israeli newspapers.
Luther and Copernicus
In the 16th century AD the worldview was genuinely geocentric. The discovery of the New Continent by Christopher Columbus and his crew had made it certain that Earth indeed is a ball and not flat. But the ideas of Nicolaus Copernicus that the world is actually heliocentric and Earth rotates on its orbit around Sun was too much for many. Since the theory was rather abstract and mathematical it did not raise such a storm as the discoveries of Galileo half a century later which were based on actual observations using the newly invented telescope.
Elderly Martin Luther heard of the theories of Copernicus and ridiculed them. He correctly pointed out at that such an idea is in conflict with the story in Joshua 10. For how could Joshua stop the Sun and the Moon if they were not put up there in the firmament above Earth as the Bible tells us?
My personal experience
On early morning some years ago I was driving down the Beth Horon highway and turned to the smaller road that passes Emmaus-Nicopolis where we were at that time excavating the area.
I simply had to stop the car in the Valley of Ayalon (Aijalon) to admire the view - while the Sun was rising in the East the full Moon was still visible in the west in the direction of the Great Sea of the Bible.
It was a totally quiet moment, morning mist was bluish and the atmosphere made both the Sun and the Moon appear larger than usual.
In my bones I could feel the mysterious power of the archaic poem and combat story in Joshua 10. It must have been quite a battle as the Lord of the Hosts participated in the fight that day from heavens and Joshua commanded even the Sun and Moon to stop on their paths so that there would be enough light and time to kill all those Amorites!
(Much has been written about this subject trying to bypass the problem that Luther noticed and to prove in one way or other that the Biblical narrative is true.)