Totally Off The Wall.

[Hungry4info]

1. I heard doppler used in Astromony? How is it used?

Yes. The Doppler shift of absorption or emission lines in the spectrum of a body can tell you about the body's velocity. See this link.

2. Can it be used to determine the speed of the astral body?

Partially. The velocity of an object toward or away from the observer (that is, the object's radial velocity) can be measured this way. But it cannot detect velocity tangental to the observer. If the object is moving in the sky but not getting any closer or father, then there will be no Doppler shift.

3. If it is used, what is the formula? (I know the one for underwater sound transmission or at least I think I remember it)

4. If 2 or more sensors (i.e. an earth based telescope and a distant satellite) detect a common occurance/evolution, can position of the object be refined using time difference fixing)?

Probably. I don't think it would be much different than your experience with with sonar in water. But it would be very difficult to get a large enough separation between the two sensors to make a difference for astronomical bodies that are light years, or thousands of parsecs away.

If the type of gear/procedure exists, how accurate is the result?

While I think it's probably possible, I do not think this has ever actually been done.

[selden]

Q#4: a comparable sensing method used in both optical and radio astronomy is called interferometry. It's used to get extremely precise position measurements. I'll leave it to you to consult Wikipedia and other resources for more information.