Errors in Death from the Skies

[hhEb09'1]

Archaeologists should be changed to geologists in the 2nd edition though.

Or maybe paleontologists. I wasn't sure what the archaeology reference was.

One more quibble, which is more just a question of interpretation, maybe. In DFTS, p.204, it says "As the Sun evolves during its time as a red giant, it will eventually span a third of the sky. It's difficult to appreciate how big that is. Go grab a yardstick. Put your left hand on one end, and your right hand at the 24-inch mark. Now extend your arms all the way out. When the Sun is at its greatest extent as a red giant, it will just fit between your two hands."

When I read that, I assume a third of the sky means a third of the sky from horizon to horizon, or sixty degrees--which makes the trig easy. If the angle formed by your two hands and your eyes (I know your eyes don't make a point ) is sixty degrees, then the other two sides of the triangle are also 24 inches.

Usually, these sort of body-based measurements are relative rather than absolute. For instance, holding your thumb at arm's length might result in the same approximation for a child as well as an adult. But in this case, it seems like the arms involved have the hands two feet from the eyes. I can see where there might be some variation there.

And then there's the problem of whether to measure at the base of the hand, or the tip of the hand. OK, sorry I brought it up.

[George]

I thought the Sun might nearly reach our orbit, thus it would be closer to a 90 deg. arc in diameter.

[hhEb09'1]

I thought the Sun might nearly reach our orbit, thus it would be closer to a 90 deg. arc in diameter.

That would be 180 degrees.

But DFTS is talking about a specific point in the solar evolution, rather than any ultimate result. It goes into a lot of gory details along the way. Everyone should have a copy.

[George]

Oops. Yes, of course, 180 deg at noon.

I wonder if the Sun is not an orange giant at 60 degrees?

[matthewota]

All this, and I found only one mistake in his first book...

[Charlie in Dayton]

My copy of DEATH FROM THE SKIES arrived the other day (ordered thru the JREF and suitably autographed by the BA his own bad self), but it'll be a couple weeks 'fore I can read it...

Mom paid for it, I ordered it, but I had to give it to her unread so I can make it look good Xmas morn in front of the rest of the fambly unwrapping it and exclaiming vociferously...

Oh well...the ink won't disappear before then...

[Another Phobos]

great book...but be sure to give credit to Douglas Adams for the "best bang since the big one" joke

[hhEb09'1]

I think Mrs. Fred Hoyle was said to have made that joke in 1952

[publiusr]

Errors from the skies instead of terror from the skies?

crickets...

[mahesh]

I think Mrs. Fred Hoyle was said to have made that joke in 1952

A well-Hoyled joke!

i love it.

[makuabob]

Perhaps the BA would like to correct this bad astronomy:

"...in 2005, one extraordinary flare launched a blast of protons that reached the Earth in just fifteen minutes, indicating that they were travelling at <i>one-third the speed of light</i>." p. 46, Death From The Skies!

It's not hard to do the math,... Earth is 8-1/3 light minutes from Sol, protons make the trip in fifteen minutes,... ergo, the protons were travelling at MORE than one-half the speed of light.

Or,...

The light from the flare AND the protons left Sol at the same time and the protons arrived at Earth fifteen minutes AFTER the light from the flare, thus the total trip time for the protons was 8-1/3 + 15 = 23-1/3 minutes,... or about 1/3 the speed of light.

I know qualified proof-readers ARE hard to find but this math error just JUMPS out and grabs you. I'll be reading the rest of the book,... some day.

[hhEb09'1]

I know qualified proof-readers ARE hard to find but this math error just JUMPS out and grabs you. I'll be reading the rest of the book,... some day.

I did note that one when I first read the book, and gave it the benefit of the doubt. I haven't done the calculations, but I figured if the protons reached us at ¹/₃c then they probably were going much faster when they were ejected, which would have made the travel time faster. Not sure if that is a reasonable number or not, but it should be simple to calculate.

[makuabob]

I did note that one when I first read the book, and gave it the benefit of the doubt. I haven't done the calculations, but I figured if the protons reached us at ¹/₃c then they probably were going much faster when they were ejected, which would have made the travel time faster. Not sure if that is a reasonable number or not, but it should be simple to calculate.

Gosh!, I don't want to sound too picky here,... but the book says,

...one extraordinary flare launched a blast of protons that reached the Earth in just fifteen minutes,...

meaning, according to this quote, the protons took fifteen minutes to travel from the sun to the Earth. That's an average speed of more than 0.5c during the trip.

There is a mistake somewhere in that statement. Either the protons were moving MUCH faster than 0.33c OR the protons arrived fifteen minutes AFTER the light that showed a flare had occurred. It can't be both.

[Gillianren]

You know, Makuabob, you can criticize without being rude. You might want to try it.

For example, I'll note that--in the chapter titled "The Stellar Fury of Supernovae"--it refers to someone's not being able to use a telescope because there's no electricity. Well, I would be able to use mine with no electricity, because there are no electrical components to it. I would posit that most casual readers' telescopes, assuming they have one at all, have no electrical components to them. I know this is not a mistake, but it may be confusing to those people who don't know about those telescopes which do have electrical components. I don't think the average person realizes that Big Scopes^TM have a lot of electrical components.

[hhEb09'1]

meaning, according to this quote, the protons took fifteen minutes to travel from the sun to the Earth. That's an average speed of more than 0.5c during the trip.

There is a mistake somewhere in that statement. Either the protons were moving MUCH faster than 0.33c OR the protons arrived fifteen minutes AFTER the light that showed a flare had occurred. It can't be both.

I don't have the book in front of me right now, to quote, but if I remember correctly one possible interpretation was that the ¹/₃c speed was measured at the earth--and the particles would have lost energy as they climbed up the gravity well from the sun. So, they would have lost velocity, and they would have averaged more than ¹/₃c.


As you point out, it seems that average speed would have been even greater than ¹/₂c in order to make the journey in fifteen minutes, but I wasn't sure that that was an unreasonable number.

I'll do a little tink.

[Gillianren]

Page 148--"Anytime matter falls . . . ." It should be "any time."

[hhEb09'1]

As you point out, it seems that average speed would have been even greater than ¹/₂c in order to make the journey in fifteen minutes, but I wasn't sure that that was an unreasonable number.

That's probably an unreasonable number, the velocity of the particles would maybe only decrease by ballpark 100 km/s. Good catch. I wonder where the numbers came from, it seems the book should have said more like twenty-five minutes.

[makuabob]

You know, Makuabob, you can criticize without being rude. You might want to try it...

Hmmm,... Stating facts is rude?

As I mentioned, however, the sentence is wrong as it is written. The author says the protons made the trip in fifteen minutes, indicating that they were travellling at one-third the speed of light. Regardless of what speed they were making when they arrived at earth, if they took fifteen minutes to travel from the sun to the earth, their average speed was better than half the speed of light.

If the sentence had said, "...one extraordinary flare launched a blast of protons that reached the Earth just fifteen minutes later,..." there would be no problem since most reading the book would know it took 8-1/3 minutes for the light from the flare to arrive at earth and the protons, having left the sun at the same time as the light, would be following at a slower speed. All of this was explained in my first posts.

I have re-read my earlier posts cannot (obviously!) detect 'rudeness.' Since you can, please do me the favor of pointing it out. It can become a learning experience either way.

[Gillianren]

I have re-read my earlier posts cannot (obviously!) detect 'rudeness.' Since you can, please do me the favor of pointing it out. It can become a learning experience either way.

Easily.

I know qualified proof-readers ARE hard to find but this math error just JUMPS out and grabs you. I'll be reading the rest of the book,... some day.

Gosh!, I don't want to sound too picky here,... but the book says,

There is an unnecessarily snarky tone to both. I'll also note that you use inexplicable commas before your ellipses. You might want to look to that. (See how snarky that sounds?)

[geonuc]

I have re-read my earlier posts cannot (obviously!) detect 'rudeness.' Since you can, please do me the favor of pointing it out. It can become a learning experience either way.

I saw it, too. While you probably have found an error, stating that the math is easy to do and the error jumps out at you is a commentary on the general quality of work done by the author and the copy editors, which is not necessary.

[Gillianren]

Oh, and the copy editors probably didn't do the math, either; copy editors are not mathemeticians by training. Another editor should have caught it, but what the copy editor should have caught was the error I pointed out.

[geonuc]

Oh, and the copy editors probably didn't do the math, either; copy editors are not mathemeticians by training. Another editor should have caught it, but what the copy editor should have caught was the error I pointed out.

Just to be clear, it was I who said copy editors; makuabob said 'qualified proof-readers'.

[makuabob]

Clearly I have, totally by accident, wandered into the the inner sanctum of the High Holy Church of the Bad Astronomer and yelled out a terrible blasphemy.

I will now wander right back out. Won't be back... "Kirk out!"

[slang]

I don't have the book so can't put the disputed quote in context, but Wiki says:

A solar flare on January 20, 2005 released the highest concentration of protons ever directly measured, taking only 15 minutes after observation to reach Earth, indicating a velocity of approximately one-third light speed.

(bold mine) Context in the book might imply Earth observation time, but it's not obvious from the quoted bit. IMHO it's badly worded rather than absolutely wrong.

[AndreasJ]

I prefer to think we're all right

Kreide is also the German word for the Cretaceous, according to this wiki page.

Cretaceous literally means "of chalk". The period is named in both English and German for the massive layers of chalk laid down in much of Europe during it.

BTW, the "K-T event" is now better called the K-Pg (Cretaceous-Paleogene) event, as the Tertiary has been deprecated.

[geonuc]

BTW, the "K-T event" is now better called the K-Pg (Cretaceous-Paleogene) event, as the Tertiary has been deprecated.

Say what?

[AndreasJ]

Say what?

The Tertiary period is no longer recognized by the International Commission on Stratigraphy (an international body charged with standardizing and correlating stratigraphic schemes across the world) and many (most?) geologists no longer use it. Instead the early and middle Cenozoic is divided into the Paleogene (Pg) and Neogene (Ng) periods.

A related debate is ongoing concerning the Quaternary - it may end up being abolished too, in which case we're still living in the Neogene, or, as seems now more likely, redefined to begin with the onset of the current glacial cycles ~2.6 million years ago. See this chart and note in particular the footnote in the lower left.

[geonuc]

Yes, I understood that part. Your use of the word 'deprecated' threw me.

In any case, I don't necessarily think it's an error to use Tertiary in a book such as the one under discussion; for those likely to read it, K-T boundary is a recognized term.

[AndreasJ]

Oh, I wouldn't call it an error either. "K-Pg" is preferable, but "K-T" isn't wrong.

[dirty_g]

Clearly I have, totally by accident, wandered into the the inner sanctum of the High Holy Church of the Bad Astronomer and yelled out a terrible blasphemy.

I will now wander right back out. Won't be back... "Kirk out!"

It's true. You can be rude to people on the conspiracy or ATM threads but not about the bad astronomer......... Yes he was a little rude in his comments. Snarky in tone but its nothing I have not seen the regulars here do plenty of times before.