“It’s not a question of if we’re gonna get hit by an asteroid at some point; it’s a question of when.” ~Gordon Dillow
Fire in the Sky.
A book, Gordon notes, is essentially a long article made as dramatic and as interesting as possible while giving out necessary information. It took him a year to do the research and the initial writing, and then another six months editing it. Gordon remarks that writing a book means staying on the same subject for that long and getting immersed in it, to the point of others not quite getting interested in what he talks about.
It has only been in the past two centuries that people have learned that asteroids existed, as the telescopes prior to that weren’t powerful enough to pick these up. Gordon adds that, originally, people thought that asteroids were located between the orbits of Mars and Jupiter, but occasionally some asteroids veer off from these orbits to fly near the earth; these are called “near Earth objects,” or “near Earth asteroids.” The increased sophistication of telescopes in the past two decades has led to the discovery of some 20,000 asteroids which come close to Earth, at distances of a few ten thousand miles to a million miles. Some of these objects do enter the Earth’s atmosphere, and the smaller ones burn up in the atmosphere; this happens around once a month, and some of these, such as the 2013 Chelyabinsk event, cause noticeable amounts of physical damage when these exploded. The larger ones, those around 30 - 40 yards wide, actually make it to the Earth’s surface, which they then impact, and Gordon also adds that there are likely “tens of thousands” of other asteroids which haven’t been discovered yet, which could potentially impact the Earth, noting that, if there were a light on each and every such asteroid, the night sky would light up “like the Fourth of July.” He likens the near Earth asteroids to a Nascar racecar which leaves the track and every other car in the race and starts “doing donuts” in the infield, with the Earth being in the infield, in this analogy.
Where size is concerned, asteroids can be as large as the largest, Ceres, which is 600 miles wide, or as small as a yard wide, and the smaller asteroids outnumber the larger ones by a great deal. Most of the ones that we humans need to be concerned about are those 50 - 100 yards wide, as these are the ones which are large enough to hit the earth. Asteroids also have varying densities, which means that the asteroids which are composed mostly of metals, which are in the minority where asteroid numbers are concerned, are more likely to survive burning in the Earth’s atmosphere to hit the Earth, thanks to their density, while those made of rock are less likely to do so. Gordon also remarks that, in 2029, a thousand-foot-wide asteroid named Apophis will pass within 19,000 miles of the Earth (by comparison, the orbit of a geosynchronous satellite is around 22,000 miles, and the Moon orbits the Earth at around 240,000 miles).
Where heavenly bodies and events are concerned:
- Meteors refer to the streak of light created by a small bit of space rock burning up in the atmosphere, thanks to its enormous speed.
- A meteorite is space rock which doesn’t disintegrate in the atmosphere and thus manages to hit the ground.
- An asteroid is a body in space which is made of rock or metal, which ranges from a yard wide to hundreds of miles wide.
- A comet is a body which comes from the outer edges of the solar system, which are made up of ice and dust and rock. The ice turns into gas as it approaches the Sun, thanks to the Sun’s heat, creating the cometary tail.
(Gordon adds a caveat, in that the definitions noted above aren’t hard and fast ones, as scientists and astronomers “just can’t seem to get together” on exact definitions. That said, these definitions are the ones generally used.)
Where the dinosaur extinction theory is concerned, Gordon notes that an asteroid around six miles wide delivered the killing blow and created a crater around a hundred miles in diameter. This damage was caused, despite the relative size of the asteroid to the Earth being akin to “a pea-gravel at a giant boulder, due to the enormous speed with which the asteroid hit the Earth. (As an aside, Gordon remarks that this was, eventually, good for us humans, as mammals then took over from the dinosaurs in the ecosystem.) Gordon notes that one might not think of the air as being able to exert a great deal of pressure, but he then notes the amount of pressure one would feel if one stuck one’s arm out of a car at 60 miles per hour, then if one did that when the car was travelling at 400 miles per hour. “It’s almost like running into concrete,” Gordon remarks where asteroids hitting the Earth’s atmosphere at the speeds they do is concerned.
Gordon notes that asteroids enter the Earth at regular intervals, and that most of these aren’t noticed by humans, pointing to an asteroid event over the Barents Sea in 2016, one which released energy equivalent to ten Hiroshima atomic bombs and which was noticed only a few months later, when scientific data was reviewed.
Gordon notes that people should be “leery” of a lot of the stories about asteroid impacts, as these tend to be sensationalized, and that serious people are looking at the issue. As this issue is a long term one, any solutions we can apply are likely to benefit our grandchildren and great-grandchildren.
Purchase from Amazon: FIRE IN THE SKY: Cosmic Collisions, Killer Asteroids, and the Race to Defend Earth by Gordon Dillow