h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Entry: Astronomy - Near Earth Objects - A927173
Author: Sir Temporal Bandit, Knight of Dubious, But Still Perfectly Seamless Logical Arguments, Keeper of the Lost and the Freebie - U214504

I've had a couple of people tell me they think this is ready, and after Em's help with the table, I think it's worth putting it into PR. So come on, let me know what you think.

TK

Like I said before, it's a great entry - well done!

Now to throw in the mandatory .

- The table backgrounds are a little too bright just now, in my opinion. I'd suggest using #98FB98 for the Green Zone; #FFFACD for the Yellow Zone; #FFD700 for the Orange Zone and #FA8072 for the Red Zone.

- The first headings, subheadings and text - "Near Earth Objects" to "What is a ‘Near Earth Object’?" - should be removed. Starting entries with a Header of Subheader doesn't look very nice, and "[Originally submitted by me as part of the first year of my degree course]" doesn't add anything to the entry. Therefore, you should start with the quote.

- Again, stylistically, it would look better if you removed the quotation marks from the opening quote, and instead put the whole quote into italics.


Well done again! I'll post here if I come up with any more suggestions.

RhoMuNuQ

Done, apart from the colours bit.

TK

first things first, the crater in the yucatan peninsula in the gulf of mexico is spelled as "chicxulub".

other things I would comment on are your assesment of risks and your conclussions.

the risks are significant, not in terms of the actual likelyhood of you personally ending up dead, but because if anyone ends up dead, then many hundreds (or many more) of people would end up dead.

government risk assesments point out that even by their standards, the amount of money we should be spending on these objects is massively more than we are currently spending.

as to your conclusions, we are currently overdue for another "tunguska" sized event, and the consequences if it hits a major city would be severe.

also, we still are not sure exactly what exploded above tunguska, so you need to change your entry to reflect that.

most of the most risky objects we have found recently have only been spotted days after they just missed us. this is still the most likely scenario.

to do anything about a serious strike, we would need a couple of years advanced warning about it, and currently we don't get even a couple of days warning in most cases.

Thanks for pointing out the typo- missed that one, lol.

A lot of your suggestions where already in the text, so I've tried to re-word them to make them more obvious- I guess if one person doesn't catch them, it's probable that others won't.

And the Tungusky bit is in it's own little section- I didn't see the need to repeat this in the conclusion.

Thanks for your input, much appreciated

TK

It's looking good!

Are you sure about not making the colour change? The bright colours you're using just now don't really fit in with the style of other Edited Entries, in my opinion, and the shades of orange and red make the text quite tricky to read.

RhoMuNuQ

Interesting entry.

I don't understand this bit:

'There are three types of near Earth orbit: Amor, which have orbital radii between 1.017 and 1.3 Au; Apollo, with orbital radii between 1 Au and 1.017 Au; and Athen, with orbital radii of less than 1 Au. '

What's an 'Au'?

Why were the orbits called Armor, Apollo and Athen?

The section directly underneath the heading entitled 'Impact: Earth' is about Jupiter, although I can see that there are a number of sub-headers underneath. I found it a bit confusing. You might want to rethink this and maybe have a sub-heading Impact: Jupiter preceding that paragraph.

An 'AU' is an 'Astronomical Unit', about 150 million kilometres. I agree that it should be defined in the entry.

I'm afraid that I don't know the origin(s) of the names of the types of orbit.

RhoMuNuQ

O.k, I've updated the AU bit.... sorry about that, should have seen that myself.

As for the names of the types of orbits- as far as this entry is concerned, they're just greek words: asking why they're called Amor, Apollo and Athen is a bit like asking why Jupiter, Saturn and the Moon are called Jupiter, Saturn and the Moon... difficult to go into without introducing an entirely new entry. Maybe someone will do an entry on the naming of astronomical stuff, etc?

Thanks for your help,

TK

I think this is a great entry

I do agree with Rho about the table colours. Perhaps changing the font colour to white in the red and orange sections would improve things.

I'll point this one out to the h2g2as members.

turvy

Something like that will probably be changed, if deemed necessary, in the sub- editing process: I'm not too hot on the GuideML stuff, so I don't want to mess around with stuff I don't know how to do until I've got time to think about and do it properly.

TK

Take a look here for the changed GuideML and see what you think.==> A1081612

I have only altered the font colour in the orange and red parts of the table and nothing else.

If you don't already know you can inspect the GuideML by changing the 'A' number to 'test'. So 'A1081612' becomes 'test1081612' in your browser address bar.

I think the text in the orange section is better in black, personally.

turvy

THis is an excellent entry. I thought the table was particularly effictive.

Have you considered adding a one line rebuttal of NEOs shown in recent films?

My proposed changes to the table are shown in A1082017 (GuideML at <./>test1082017</.&gt.

I'm afraid that tags aren't allowed in Edited Entries.

RhoMuNuQ

an error in the article.

you say "we would have 2 to 20 years warning", and it should be "we would need".

also, you say that the approach would be head on, but actually, you want to sneak up behind it. this is one of the mistakes made in just about every recent film (the other is the one about blowing it to bits, changing a cannon ball into a shotgun blast).

current evidence says that at the moment, the ikeliest scenario is that we will spot the dangerous asteriod or comet as it is entering the atmosphere. in fact, most of the recent near misses have not been seen until days after the closest approach.

O.k, I've changed the warning bit.

The other two bits you mentioned are already in there, just written differently. However, as you're the second person to claim that they are not there, I've put extra bits in to explain these more explicitly. Seems a little ott to me, but I guess some people find the concepts harder to take in than others- I know that if I was reading an entry on football, there would be bits I didn't have a clue about that most people would just take for granted as gospel knowledge.

TK

I think the reason people claim that they are not in there has something to do with you saying "the rocket will have to be fired when the NEO is very close to Earth (for fuel and accurate aiming purposes)", and treating the head-on impact as practical.

it is no currently within forseeable technology to detonate a head on impact due to the triggering constraints.

to do so, you have to detonate your warhead sufficiently in advance that it blows up just ahead of the neo. if it is too far away, it does nothing. if it is too close, it breaks up before it can explode.

the problem is that the time between too far away and too close is rediculously small in a head on trajectory.

it's like deliberately flying 2 concorde aircraft head on into each other, the closing speed is just too fast (by orders of magnitude). this is why you need the long warning. it allows you to do things like slingshoting your warhead around another planet, so it come up from behind, and the closing spead is managable.

ps you mention nearearth and their website, but despite mentioning the domain name, you have not made it into a link.

Great article!

However, I have something you might want to mention in it. Apparently, in September, there was another atmospheric explotion of an impactor in Siberia, the biggest since 1908. I got the story from Space.com astronotes. I can give you a link if you want.

Yeah, post that here if you could- I hadn't heard about that one.

TK

Updates:

- Added a bit more on the rocket thing (no one seems to be happy with that yet. It seems to be difficult to please everyone whilst keeping with the NEO theme and not turning it into an entry on ballistics. It might be that that section deserves an entry to itself) and a couple of footnotes.

- changes the nearearthobjects reference into a link- thanks for that, I'd missed it.

TK