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Molly Cule
153412.  Sun Mar 04, 2007 5:47 am Reply with quote

Life lived at The Equator is a life lived to its fullest.
Apparently. Have a look at what you're missing...

Molly Cule
154327.  Tue Mar 06, 2007 4:28 pm Reply with quote

Space ports and space elevators will be built on the equator as land on the equator is moving faster than any other point on earth. The velocity means less fuel will be needed to lift off.

Molly Cule
154329.  Tue Mar 06, 2007 4:32 pm Reply with quote

When a sailor first crosses the equator he can expect an ‘Equatorial baptism‘ or a ‘crossing the line’ initiation. In the British and U.S navies seasoned sailors are called shellbacks whilst the uninitiated are called Pollywogs. The can be quite brutal with sailors being whipped, having to kiss the feet of shellbacks and having to perform all sorts of stuff. A tape of the ceremony in the Australian navy was shown in 1995 to public outcry as sailors had their trousers pulled down, stuff poured all over their bums and then had poles pushed up them. !

Ceremonies also happen for crossing other lines, there is the
Order of the Blue Nose for sailors who have crossed the Arctic Circle.
The Order of the Red Nose for sailors who have crossed the Antarctic Circle.
The Order of the Golden Dragon for sailors who have crossed the International Date Line.
The Order of the Ditch for sailors who have passed through the Panama Canal.

Molly Cule
154330.  Tue Mar 06, 2007 4:34 pm Reply with quote

Geostationary satellites orbit the earth once a day directly above the equator, their orbital speed exactly matches the rate at which the earth rotates so they seem to continuously hover over one position on the earth’s surface. They stay at 22,300 miles above earth. They don’t need to be tracked so are cheaper to use than other satellites.

They were thought up by Arthur C. Clarke.

These satellites are used for global communications, weather forecasting and television broadcasting. So this programme will be sent to the equator and back before you watch it.

The first geostationary satellite was called Syncom 3 and was used to transmit the Summer Olympic Games in Tokyo in 1964 to the U.S. These Olympics were the first tv programme to cross the Pacific Ocean.

154416.  Wed Mar 07, 2007 3:51 am Reply with quote

Presumably we only realised the equator existed fairly late in the day, I think someone said that it was Mercator who named it.

Is there any evidence of ancient cultures realising the line's significance?

Frederick The Monk
154420.  Wed Mar 07, 2007 4:05 am Reply with quote

c.1391, from M.L. æquator diei et noctis "equalizer of day and night" (when the sun is on the celestial equator, twice annually, day and night are of equal length), from L. æquare "make equal, equate." Sense of "celestial equator" is earliest, extension to "terrestrial line midway between the poles" first recorded in Eng. 1612.

According to the very reliable Lacus Curtius , Claudius Ptolemy, the 2nd century AD astronomer and geographer, measured his co-ordinates for the Geographia from the Equator:

Ptolemy's coördinates are in degrees and minutes (360 degrees to a circle, 60 minutes to a degree), just like our own. His North-South coördinates (latitudes) are measured like our own from the Equator. His East-West coördinates (longitudes) are measured eastward from a point somewhere W of the westernmost point he catalogues in the Geography, traditionally read as "east of the Blessed Isles": for that reason, in this Web edition I've indicated latitudes with the familiar degree sign (e.g., 5°00N), but his longitudes with an asterisk instead (e.g., 25*00).

154423.  Wed Mar 07, 2007 4:14 am Reply with quote

So Ptolemy knew where the equator was? Presumably by finding the point where the length of a day never changed?

Thinking about it, I would have thought that cultures in equatorial countries would have easily found such places and that they would have been venerated.

Frederick The Monk
154428.  Wed Mar 07, 2007 4:44 am Reply with quote

Ptolemy knew there must be such a line because he knew the earth was a sphere (ish) as Eratosthenes proved that in the 3rd century BC using a stick and hole in the ground.

154439.  Wed Mar 07, 2007 5:11 am Reply with quote

Molly Cule wrote:
They were thought up by Arthur C. Clarke.

Oh no they weren't!

(Is it panto season already?)

Geostationary orbits were originally proposed by the great Russian scientist Konstantin Tsiolkovsky at the beginning of the 20th century. Later, in the 1920s, Herman Potočnik wrote "Das Problem der Befahrung des Weltraums - der Raketen-motor" (The Problem of Space Travel - The Rocket Motor) in which he proposed putting a space station in a geosynchronous orbit and wrote about radio communications between the station and Earth.

What Arthur C. Clarke did, in his article in the October 1945 edition of Wireless World, was to propose the idea of using communication satellites as relays for messages. In this way, he proposed that a system of only three satellites in geosynchronous orbits would be able to allow instantaneous communication across the entire world (although the north and south poles might not be so well served).


Molly Cule wrote:
These satellites are used for global communications, weather forecasting and television broadcasting. So this programme will be sent to the equator and back before you watch it.

Whilst it's certainly true that satellite TV gets bounced off satellites, is it true that terrestrial broadcasts go via the equator too? Or do they just get transmitted by wires or microwaves to the transmitting stations?

154441.  Wed Mar 07, 2007 5:15 am Reply with quote

...and as soon as you have a sphere 'in your mind', it's straightforward to realise that there must be a line that wraps around it, taking the longest path, and equidistant from the poles...

Amusingly, Uranus's equator is sideways on (because the whole planet is tipped up on its side - it has an 'axial tilt' of about 100 degrees). This means that as it travels around the Sun, one pole will have about 40 years of darkness, while the other has about 40 (Earth) years of light. Then for the other half of the Uranus year, the poles reverse their weather. If there's life on it, it'll be migratory...

It's not fully understood why Uranus is on its side, but judging by one of its moons, it's been hit by some fairly large chunks of rock in the past:

154442.  Wed Mar 07, 2007 5:16 am Reply with quote

We could probably ask the panel what they think the Tropics of Capricorn/Cancer really signify, because not a lot of people know that...

154448.  Wed Mar 07, 2007 5:32 am Reply with quote

Gray wrote:
We could probably ask the panel what they think the Tropics of Capricorn/Cancer really signify, because not a lot of people know that...

As far as I can remember, Cancer was filthier than Capricorn, but "Quiet Days in Clichy" was filthier than both of them put together.

154465.  Wed Mar 07, 2007 6:00 am Reply with quote

There's no way that 'terrestrial' TV will use satellites for home broadcast, as the airtime would be insanely expensive. And anyway, why would they, if it's only going 'down the road'.

They use microwave relays like this one:

or, if they can't 'see' one of their towers, they occasionally use a satellite (e.g. the King's Christmas Eve broadcast), but more commonly a leased line or optical fibre, which have plenty of bandwidth and no lag.

Molly Cule
154471.  Wed Mar 07, 2007 6:15 am Reply with quote

Oh well, it was a nice, not very well thought out thought!

Another thing you can clear up for my Mum ! - if that diameter of the earth is 26 or so miles greater at the equator than at the poles and we are all hurtling around space at 66,000 miles an hour and people on the equator are hurtling even faster.... could someone who lives at the equator, then moves to live at the south pole - unlikely i know - feel the difference? People who live at low altitude feel it when they get high and vice versa, i know it is totally different but still....

154481.  Wed Mar 07, 2007 6:35 am Reply with quote

The difference in the apparent gravity (i.e taking into account the speed you travel) at the equator compared to the poles is proportional to the square of the speed divided by the radius (distance from the centre of the Earth).

Acceleration in a circular orbit, IIRC, is given a = m(v^2)/r

At the equator, your speed is about 450m/s (roughly 1,000mph), and the radius of curvature is about 6,378,000m, giving you a per-kg acceleration of about 0.03m/s2 upwards.

This equates (ha ha) to about 0.3% of 'normal' gravity (9.8m/s2), so wouldn't be noticeable for a person jumping up and down. If you building some huge structure, though, I imagine it would be significant...


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