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

As to the origin of the moons, I think I would end up doing exactly what Isaac Newton counseled not to do: putting in conjecture about all things. There are varying hypothesis as to why satellites are in the orbits they occupy. I would rather mention the moons and what we know of them.

In response to Gnomons assertion that debis and remains of an unformed planet are the same I give this from dictionary.com
Debris (n)
the remains of anything broken down or destroyed.
since the planet had not yet formed it is not broken down.
I will change the word remains to left overs to clarify.

The start of this Entry is a bit abrupt:

'From the time of the ancient Babylonians and Greeks observers have wonderded what these 'wandering stars' are and how they are related.'

i.e. I think you should've explained what 'wandering stars' are first.

P'haps s'thing like:

The solar system is a family of 8 (or 9) planets orbiting 'our star' the Sun. To the ancient Babylonians and Greeks they were known as 'wandering stars' because they appeared to move against the background of 'fixed stars'

The bit about Proxima Centauri is supeffluous IMO, as it has nothing to do with our Solar System'.

However, you could perhaps include it into the para on the Sun by saying s'thing like:

The Sun (Sol)

The centre of our Solar System is the Sun, a rather ordinary star...
After the Sun our nearest star is Proxima Centauri at a distance of ...

Within this para on the Sun you could perhaps say that the Sun rotates once in 24.5 days, althougfh its rotation at the equator is rather slower at 34 days (Average = 29.25 days). Everything pertaining to life on Earth is linked to this rotational period e.g. human biological cycle, female fertility...


Some extra info about the planets:

Mercury: The side facing thew Sun is very hot (about 430 deg C - hot enough to melt lead - MPt = 327 Deg C)

Venus: Atmosphere is mainly carbon dioxide. This traps the Sun's heat by the 'Greenhouse Effect, so that Venus is even hotter than Mercury - which is closer to the Sun.

Mars: Has a thin atmosphere of carbon dioxide. It was the first of the planets to be visited by one of our spacecraft. A huge amount of water was discovered to be present just below the surface in 2002, and this is of interest to scientists looking for signs of life on other planets. The length of the Martian day, at 25 hours, is similar to that on Earth, a total coincidence, but a happy one for future colonists!

Jupiter: Giant Red Spot is 3 x the size of Earth. Jupiter is a key factor in preserving life on Earh as its enormous gravity act as a cosmic vacuum cleaner ( or shield) protecting Earth from cometary impacts. It is a 'failed star'

Venus: The largest moon, Titan, is larger that either Mercury or Pluto.

Uranus: Discovered in 1781 by William Herschel, who built a mirror in his kitchen...

Neptune: The Great Dark Spot is a storm the size of Earth.

Pluto: Discovered in 1930. Has a very thin atmosphere of methane. Some think it's just a giant Kuiper Belt Object.
































.

Oops, had a little info about the Kuiper Belt and Oort Cloud as well.

Asteroid Belt contains approx 300,000 asteroids.

Kuiper Belt contains ca 70,000 objects.

As you've mentioned atmosphere for most planets, Jupiter's is mainly liquid hydrogemn and helium. It has no solid surface.

I wouldn't say that about cycles of life on the earth being linked to the average rotational period of the sun, as it's highly suspect. It's much more likely that these cycles are linked to the length of a month, which happens to be the same value.

Well, see this brief from NASA whih says that virtually every physical and biological cycle on Earth is driven by energy from the Sun:

http://edmall.gsfc.nasa.gov/inv99Project.Site/Pages/science-briefs/ed-stickler/ed-irradiance.html

Hmm. Maybe one should just say that 'energy from the Sun drives virtually all the cycles of life on Earth', i.e. not link it to rotational period

I have used that phrase.
I am not using everything from post#23 as I think some things are better left to the individual article to tell.

I don't understand this in post 23, <>

could you clarify what you meant, please BigAl?

GB

perhaps he meant Saturn's moon
Here are equatorial radii
Titan 2,575 km
Mercury 2,439 km
Pluto 1,151 km

Yes I did mean Saturn's moon

Observers have wonderded > wondered



The Sun (Sol)

A great star....

Well, as I said in Post 23, it's really just a very ordinary star . Might be worth emphasising that it's a 'main sequence' star on the Hertzsprung-Russell Diagram...

The sun is not really an average star. It is a lot bigger, brighter and hotter than average. Most stars are red dwarfs. These are so dim that we can't see any of them from here, even though one of them is the closest star in the sky to us. Of the stars in the sky that we can see, though, the sun is a fairly average specimen.

I think that's all I am going to do with that round of changes.

Is everyone OK with this update now?

or do we need another round of changes?

Entry: Update A79508 Our Solar System-an overview - A32537720
Author: Shagbark - U170775

Content:

I don't see the relevance of your quote at the top. It's a good quote about science in general but doesn't seem to have much to do with the solar system.

You still have:

"Whether they are left overs from some unformed planet, an exploded planet, or just the remains of something broken down by collision or impact is not known." -- is there _anybody_ who thinks it is an exploded planet? They did a hundred years ago, but not anymore!

to the plane of the ecliptic -- since you don't explain ecliptic, you'd be better saying "to the plane of the solar system"

Why do you list Orcus before Pluto?

Typos, grammar, formatting etc:

Could you match the link list at the top to the ones on the other solar system entries? It should start with:

Solar System

rather than:

(vertical line) System Overview

Footnote 1: remove the space before the

Gravity may made part --> Gravity made part

just the right size for carbon-based life --> and is just the right size for carbon-based life

464 C --> 464&deg;C

Giovanni Schiapirelli --> Giovanni Schiaparelli

rich in Carbon Dioxide --> rich in carbon dioxide

Neptune, the farthest planet in the system. --> Neptune is the outermost planet in the system.

They had this chunk --> they had this chunk

Can you add an explanation of what an Astronomical Unit is to your footnote?

G

thanks for the input, I will get to these later tonight.

post#21 is a good example of how that quote applies. Also the matter of how asteroids came into being. So in line with the opening quote I am eliminating that conjecture.
I have eliminated the patently absurd idea of man made satellites expending fuel to "hop over" the asteroids and then more fuel to return to the ecliptic where their destination would lie.
I have also reordered the table of trans-neptunian objects so the smallest was last.

done,I think except I searched and searched and never found the phrase 'had this chunk'