INTRODUCTION
The Holy Bible is a book about kingdoms: spiritual kingdoms and physical kingdoms and the interactions between them.
The last book of this book of books is the book of Revelation. This is a book of prophecy, some of which has already occurred but much which lies in the future, and particularly the future that is elsewhere called the 'time of the end'.
The time of the end is a three and one half year period (1260 days) that is broken up into a 2.5 year period called "the Great Tribulation" followed by a one year period called "the Day of the Lord". The first two and one half years is essentially the start of world war and man's inhumanity to his fellow man. The last year is a time of God's wrath on humanity.
During the last year the Earth will be subject to the results of a spiritual war with celestial manifestations.
REVELATION 8
In particular chapter 8 of the book talks about the Earth's bombardment by objects in space: meteoroids, asteroids and comets.
Now we have to be careful about assigning physical manifestation to what are sometimes spiritual objects. On numerous occasions, and particularly in the book of Revelation the bible uses symbology for spiritual objects. In particular, angels are referred to as stars. An example occurs in Revelation 9:1. However, in chapter 8 we know that the stars referred to here are not angels but actual heavenly bodies - not true stars but objects that initially have a star like appearance (ie points of light in the sky). We know this because when these objects fall from the sky they cause immense damage to the Earth and its inhabitants.
The relevant five verses of chapter 8 read:
8 And the second angel sounded and as it were (ie something like) a great mountain burning with fire was cast into the sea: and the third part of the sea became blood;
9 And the third part of the creatures which were in the sea and had life, died; and the third part of the ships were destroyed.
10 And the third angel sounded and there fell a great star from heaven, burning as it were a lamp, and it fell upon the third part of the rivers and upon the fountains of waters.
11 And the name of the star is called Wormwood: and the third part of the waters became wormwood (ie bitter); and many men died of the waters , because they were made bitter.
12 And the fourth angel sounded, and the third part of the sun was smitten, and the third part of the moon, and the third part of the stars; so as the third part of them was darkened, and the day shone not for a third part of it, and night likewise.
The above text is taken from the King James version of the Bible but other versions are essentially the same - a few comments have been inserted in parentheses from other versions to try and clarify the language used here.
THE FOUR EVENTS
It would appear that the above verses are describing three astronomical events of objects falling from the sky:
(ii) the second event is a large object falling into the ocean
(iii) the third event is a second large object falling onto the land and poisoning the drinking water
The fourth event appears to describe the aftermath of the first three events on the Earth's atmosphere. Dust, smoke and other debris lofted high into the atmosphere by impacts of large objects with the Earth can be expected to diminish the light coming from the Sun and the Moon (and the stars).
A GIANT HAILSTORM
The hailstorms which some of us have experienced can do considerable damage. One 30 minute event in Oklahoma caused $48 million damage.
However this is nothing compared to what is described in Revelation 8:7 . This event is describing something that affects one third of the Earth. That is, it affects almost one hemisphere, so it had to be celestial. It did not come from a terrestrial storm. It also involved hailstones that were on fire. The reference to 'blood' probably signifies a colour rather than a bodily fluid (ie they were like blood).
This is not the first time the Bible describes such an event. There were numerous giant hailstorms that occurred around the time of the Exodus (eg Joshua 10:11).
There is also another reference to such an event in Revelation 16:21 where the average weight of the hailstones is given as 25 kg.
This leads us to question what type of stones these were?
Hailstones
A text by Lamb and Verlinde (see references) states that hailstones of ice range in size from 5mm to a little over 150 mm.
Now the relation between mass (m kg) and size (diameter d metres) is given by:
Using formula (1) we can compute that the diameter of a stone of ice with a density ρ = 1000 kg/m3 is 37 cm. This is way beyond even a possible size and mass for an ice hailstone as it implies upward formation velocities that are totally unphysical and unrealistic.
However, a hailstone of stone with a mass of 25 kg , a density of 3500 kg/m3 and a diameter of 24 cm could quite easily 'fall' from space through the Earth's sky and down to the ground. Such events, although not common in recent history, certainly have occurred. And it appears that the language, either in the Greek New Testament or the Hebrew Old Testament does not insist that the stones should be made of ice. The Greek word in chapter 8 is χαλαζα (chalaza) - the root meaning of the word being 'to strike down'.
As an aside, an ice hailstone of size 150mm has a mass of 1.7 kg. And while being hit by such an object travelling at 50 km/hour would be extremely unpleasant it would not always be fatal. This to be contrasted with the above mentioned reference to Joshua 10:11.
Hailstone appearance
A meteoroid/meteorite when it strikes the ground has a hot outer surface although its core may still be cool. The time it takes to go through the atmosphere where friction with the atmosphere will heat it externally is only a few minutes at the most - not time enough for the heat to be transferred to the core. If the stone is a carbonaceous chondrite it may also be smoking when it hits the ground. In any case, enough of these will ignite grasses and start fires that will spread to the trees. (Individual meteorite falls rarely start fires).
The speed with which the a 25 kg meteorite hits the ground will be less than 200 m/s. This is a lot less than the speed it has when in space, which can range from 11 to 72 km/s (typically) near the Earth. The passage through the atmosphere reduces the speed (via atmospheric friction and ablation of the meteoroid) to what is known as terminal velocity.
A stream of a large number of meteoroids could result from a collision between two asteroids or from a large asteroid impact with the moon.
AN ASTEROIDAL OCEAN IMPACT
The immediate question with this second event is "what size is a 'great' mountain"?. The highest mountains in today's world are a little under ten kilometres in height. And just by chance, ten kilometre asteroid impacts we know are the size that produce catastrophic global events. An artist's impression of such an impact into the ocean is shown below.
A hypervelocity impact is one where the size of the impactor is so large that its velocity is not diminished by its travel through the Earth's atmosphere. The impact is more like an explosion than a normal impact as we know it. The kinetic energy of a ten kilometre asteroid is equivalent to around 100,000 gigatons of TNT high explosive. The hypervelocity impact will destroy the asteroid and dust and debris will be lofted into the upper atmosphere as well as pollute the ocean. As the typical depth of the open ocean is only 4 km, a 10 km asteroid impact will certainly expose much of the ocean floor and the oceanic crust - probably for a 100 km kilometre radius around the impact site. A very large volume of water will be instantly turned to steam.
The shockwave of the impact will certainly kill all ocean organisms over a large area and the enormous tsunami with an estimated height of 4 km will destroy many ships for thousands of kilometres.
Detailed analyses of large asteroid impacts on sea and on land is given by some of the many papers in the book "Hazards" edited by Tom Gehrels.
Where is it?
The biggest question for a large asteroid impact on the Earth in a few years time is that we now think we know the number and location of all 10 km asteroids with orbits near the Earth and none of them look like potential impactors for at least a few thousand years!
Until a few years ago this question seemed to have only the answer that no such impact was possible in the near future - although an impact with a smaller (1 km) mass might be believable in a short time scale. And even this smaller impact would have effects within those described in chapter 8 (see impact effects in the above table).
However, on October 19, 2017 the first known interstellar NEO to visit our solar system was discovered. Given the Hawaiian name Oumuamua (scout) this body is a very elongated object with a length between 100 to 1000 km and a width of a few tens of metres. As of 2025 we know now of three interstellar objects that have entered the solar system. A future such object could possibly explain how an undetected asteroid could impact the Earth with less than one year's warning.
A COMETARY LAND IMPACT
The description of the last impact event (verses 10 and 11) sounds more like a cometary than an asteroidal impactor and possibly also with respect to the poisoning aspect of the event.
The description of 'burning like a lamp' might be referring to a cometary tail.
A land impact will generate a crater, at least for a large comet. Smaller sized comets may only produce an 'airburst' because the 'crush' strength is exceeded and it implodes before it reaches the surface. However even with a multigigaton air burst a large amount of regolith will be excavated and thrown into the air for thousands plus kilometres.
The passage of the body through the atmosphere will generate an enormous amount of thermal radiation which will instantaneously ignite and destroy vegetation over a very wide area and put large quantities of soot into the upper atmosphere to join and mingle with the dust and other debris. Such a land impact is shown below.
The crater size is typically ten to twenty times the size of the impactor.
Note that the object is given the name Wormwood which means "bitter" because the most important feature of this impact is that it polluted and made bitter the waters of the springs, rivers and lakes over which its debris was scattered .
In the 1910 apparition of comet Halley (which has a nuclear diameter of about ten kilometres) astronomers detected the presence of cyanogen in its tail. Cyanogen is a colourless and highly toxic gas with a pungent odour of almonds (bitter). This discovery caused a real panic among many people at the time because the Earth passed through the tail. Scientists were quick to advise people that the concentration of the gas was so small that they had no cause to worry.
However, if a comet with large cyanogen volatiles were to impact the Earth it might be possible for wide water contamination to follow that would be poisonous to man and creatures.
The occurrence of a comet impact only months after it is first detected is not as hard to explain as a short latency asteroid impact. Long period comets are believed to come from the Oort Cloud at the outer edges of the solar system and not be detectable until their inward bound path reaches Jupiter, when its surface volatiles start to warm up and spread out into a tail. It is thus typical of such comets to make their closest passage to the Earth only 200 to 500 days after they are first discovered.
In fact, comet Hyakutake, which appears as the cover image of this web site passed within 15 million kilometres (0.1 AU) of the Earth less than 2 months after its discovery on 31 January 1996.
THE AFTERMATH
The eruption of Krakatoa in 1883 destroyed the island, created tsunamis and killed at least 36,000 people. It released massive amounts of ash and sulphur dioxide into the atmosphere leading to a global climate effect with a significant drop in worldwide temperatures and vivid sunsets for years afterward.
A large impact event is likely to have similar but more devastating effects with the lofting skyward of a greater amount and more diverse range of debris, and to higher altitudes. Volcanic debris may make it to an altitude of 50 km at most, but hypervelocity impact debris is likely to make it to altitudes of several hundred kilometres and more.
The atmospheric debris will destroy the ozone layer and will reduce the overall sunlight and moonlight reaching the surface of the Earth. Weather patterns will be totally disrupted, adding to the effects of a nuclear war which occurred before these impacts.
REFERENCES
1 Holy Bible
1 Dennis Lamb & Johannes Verlinde, Physics and Chemistry of Clouds, Cambridge University Press (2011)
2 Tom Gehrels (Editor), Hazards Due to Comets & Asteroids, University of Arizona Press (1994)
Australian Space Academy