why dosen't the earth slow down?

[redhate]

I don't know all the facts, my figures were probably far beyond abscure . According to Kent Hovind (whom I believe fully) there is no way to measure the size of the stars. The scientist who say they know the size of our stars are based on the coloration they leave or something, just listen to his radio seminar on the stars. You can visit his site at www.drdino.com. Enjoy.

 

[cquark]

Originally posted by: redhate
I don't know all the facts, my figures were probably far beyond abscure . According to Kent Hovind (whom I believe fully) there is no way to measure the size of the stars. The scientist who say they know the size of our stars are based on the coloration they leave or something, just listen to his radio seminar on the stars. You can visit his site at www.drdino.com. Enjoy.

While telescopes didn't have sufficient resolution to make such measurements in the past, with Hubble, we can measure the diameter of close red giant stars like Betelguese (see here too.)

 

[unipidity]

If you know the luminosity of the star, you asume it is a black body (or use empirical data to produce a better spectrum), get its temperature, and 'pow'... you have a 'size' measurement. So yes, indirectly measured but I would imagine more accurate than Hubble.

 

[Jeff7]

Originally posted by: unipidity
Disagree about the satellite- NASA was invstigating it as a possible propulsion source- get a satellite into low orbit and use this to boost it to geostationary, for example.

*Thinks*

We have a moving wire in a magnetic field. Thus a current. And a force acting against the movement. Hmmm. And your not going to be extracting more electrical energy than is required to boost the orbit, so your correct.

Damn.
Im sure popular science outlets were going on about the economic consequences of this.

This was in Scientific American's latest issue - electrodynamic tethers. I shall summarize the article.
A satellite in higher orbit than another station, either in lower orbit, or on the ground, and both connected by a conductive line. While it orbits, the line passes through the magnetic field of the body it is orbiting. This induces current, but also drag, so the orbit of the satellite in high orbit gradually declines. If the current flow through the wire is reversed, which can be solar generated, the force reverses, to boost the satellite's orbit. It seems like just a more efficient way of transporting energy - one advantage that this system has over conventional fuel systems used to maintain orbit, is that the satellite gains energy from its declining orbit; a regular satellite does not.
Also, a tether can be used as a way of de-orbiting dying satellites. A tether can be built into satellites before launch (or attached later, in space, but this is less feasible). When the satellite is at the end of its life, it simply deploys the tether. Drag is induced into the tether, which lowers the orbit of the satellite far more rapidly than what it would otherwise take.

Originally posted by: redhate
I've heard that something like every 10 years the earth slows down by 2 seconds (in complete rotation I guess). Whats funny is... according to the evolutionary theory... if the earth really was 4.7 billion years old. It would have been spinning so fast it would have never been able to support life. And if the earth was 4.7 billion years old the sun would have touched the earth after like 10 million years (according to scientist the sun shrinks some figure a day.

Your statement assumes that the rate of deceleration is completely linear on a graph - speed vs time. I doubt this would be the case.
And of course the sun is shrinking - it loses millions of tons of material every second, released as energy, and the solar wind. In about 5 billion years, the fusion within will no longer be able to oppose the force of gravity - the core will collapse, while the outer layers expand; the core will become a dense white dwarf star.

According to Kent Hovind

Oh no. Oh god no. I advise you find another source, maybe someone who actually has researched more materials than the Bible and supermarket tabloids.

 

[Armitage]

Yea, electrodynamic tethers are interesting. Gives the space surveilance guys fits whenever they are brought up though because they are exceedingly hard to track and the overall dynamics isn't well understood. There is currently about a 6KM piece of a tether up there that I always have to drop from collision avoidance runs because nobody knows its orientation. That's another downside to using them to assist in deorbiting spacecraft. Alot of people aren't keen on having a few KM (or even a few hundred meters) of tether dragging through their orbital space at 7 km/s due to the collision risk and the dificulty of tracking it if it breaks.

On the subject of the magnetic field and satellites ... many satellites use magnetic torquers as part of their attitude control system. It's basically an electromagnet in the spacecraft. You power it up, and it creates a reaction against the earths magnetic field to dump momentum & help maintain a given attitude