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

Jimi X (U53353) and I both thought this subject was wothy of a guide entry... so we both wrote one.
We'd like for them to be combined, please, together they make a good overview of a potentially confusing subject.

Indeed, they do. very well explained, I think.
Considering the complicated subject, it certainly'd be helpful for the reader to divide the whole article with the help of or . Yes, a bit more structure, that would be nice.

p.s. how come you know about this stuff? are you hobby-astronomers? or are you making money out of it?

-oops, no chatting. ts ts ts. (mh)

I'm studying Physics and Astronomy... I have to study these things.

Agreed - combined they would make an excellent piece.

Next the seasoned star traveller would like to see explained:

1) How your navigational computer identifies a star by its absorption spectrum.
2) How it compensates for red shift and what evasive action it takes when blue shift goes into ultra-violet.

Yep, bung 'em together. I like the little intro paragraph from JimiX, although the tables are possily a bit much

I like the tables!

*shrug*

26199

Jimi X and Joanna - I'm pleased to inform you that both of your entries will be edited into one, and eventually included in the Edited Guide. Thank you both for your excellent articles! When it does get into the Edited Guide, you will receive an e-mail letting you know - but it'll take a while!

- Lentilla

Editorial Note: This thread has been moved out of the Peer Review forum because this entry has now been recommended for the Edited Guide.

So thats why I couldn't find it earlier great!

A very nice article -- actually it made me find an error in one of mine. Since you explain both absolute and relative magnitudes, why not add the formula connecting M, m and r? I can't remember it exactly but it wasn't too complicated and one of the most important equations of astronomy.

Do you mean the distance modulus thing? M-m=5logd-5 where d is distance? (or something...)

Well, I don't like this 'log d' thing because log can't cope with distances but only with simple numbers. I looked it up: M-m=-5log(r/10pc). Further advantage: r can have any unit here.

Sorry; my astrophys. course was a year ago (!) I don't really remember the formula properly...
I don't understand about what you mean about the distance, though...

I hope I understand your question correctly. The argument of the logarithm mustn't contain units. log 5pc is merely undefined. But you _can_ say log (5pc/10pc)=log 0.5. Mostly people say log without saying that has to be in parsec and that you have to throw away the parsec itself.

Hmm... okay, I see your point, I think... I also think Im going to go and spend a bit of time with my astrophys. textbook; looks like I need to revise that course some.