That a velocity exists at all speaks to an object moving relative to another object (or to the space "the moving object" is in); an object that is not stationary has a velocity.
How are light-years measured?
- Thread starter Jacob
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gcthomas
New member
Only the angle is measured, if you know the size of the earth. The distance to the sun is then calculated from the angle.
The orbit must be approx circular because the seasons are about the same length.
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Yes. But remember that velocity is speed and a direction. How fast something is moving and in what direction gives a lot of information about what is going on in the universe.
What was the task? Finding the length of time for the traversal of Venus across the surface of the sun somehow helps us to determine an angle. I do not know the size of the earth or how to determine it. But if the earth is a sphere (it basically is, though maybe not exactly) then there may be a task of determining the angle from more than one point on its surface. So here if we have two locations on the earth from which the observation is made, we have two different angle measurements at least.
Of course this is an assumption.
You are talking about a velocity vector. Is this how you determine the difference between a velocity and a speed?
An orbit (I have heard there is an escape velocity but can't remember how it works) may have a direction or velocity, but in what sense is it a vector? Is it only a vector perpendicular relative to the distance from the earth assuming this remains the same? Or would we say the vector is constantly changing, perhaps in an ideal situation at an even rate relative to some point. I think of the object's orbit path.
Jedidiah
New member
That was the exact question that led Einstein to Relativity because the only thing resembling a static or neutral frame of reference from which to make measurements is the speed of light itself, which is always measured to be the same magnitude in every direction.
So, good question. :thumb:
Caledvwlch
New member
Why are you asking these questions here? I realize there are plenty of smart cookies around here, but why not just Google it?
It has to do with the answer Jedidiah just gave.
I actually don't know what you are talking about. You have a vivid imagination.
Caledvwlch
New member
Okay. Well I hope you are successful in your quest, whatever it may actually be.
OCTOBER23
New member
It is because you use words like assumption and yet you ask a simple question
that you should have Googled long ago.
Would you like to talk to Einstein about the Speed of light or how it bends around a sphere ?
Google it.
Da 12:4 But thou, O Daniel, shut up the words, and seal the book,
even to the time of the end:
many shall run to and fro, and knowledge shall be increased.
that you should have Googled long ago.
Would you like to talk to Einstein about the Speed of light or how it bends around a sphere ?
Google it.
Da 12:4 But thou, O Daniel, shut up the words, and seal the book,
even to the time of the end:
many shall run to and fro, and knowledge shall be increased.
To learn together, first of all. I hope that is evident in the post you responded to.
It's not about a lot of knowledge. It's about following the train of thought and understanding the history of how we have the values (for example, for constants like the speed of light) and how we have chosen to measure distance in terms of light years if that is even possible.
But though I don't see the connection to Daniel, I do believe you put forth an interesting inquiry in line with the types of things we have discussed in this thread so far.
I think your question boils down to: How is the speed of light determined?
There are some old-fashioned methods that could work quite well to look at how fast light travels, but all of them have been set aside in favor of the assumption that lightspeed is a constant (called "c").
This led to the calculation of a light year, which is a useful tool for working within the field of astronomy under the assumption of c.