Trying to understand nulling interferometry.

First of all I have gotten answers to this question from Google
Answers and HowStuffWorks and I am still confused about it.

My question is; how can you nullify the waveform from a star and be
left with the light of an orbiting planet? Now please read the
following paragraph explaining why I don't understand before you
answer.

I work with sound a lot. Take for instance a song from your favorite
band. In that sound you have the separate sounds of the Vocalist,
guitarist, drummer, and bassist. Once the sounds are mixed together
it becomes one waveform. Although your ears can pick up the
difference between the vocalist and guitarist, it is impossible to
separate those two sounds into their pure individual waveforms without
having on hand at least one of the original individual waveforms.

In the same respect when you look at the light from a star with a
planet orbiting around it that light is the combined light from both
the star and the planet. Without having at least one of the pure
waveforms of light from the star or the planet, how can you only
cancel out one? Are you assuming that all stars have the same
waveforms and just canceling the stars light with a generic star
waveform? Otherwise wouldn't canceling the stars light also cancel
the planets light?

Thanks for the help.


-Al

Albion wrote:
First of all I have gotten answers to this question from Google
Answers and HowStuffWorks and I am still confused about it.

My question is; how can you nullify the waveform from a star and be
left with the light of an orbiting planet? Now please read the
following paragraph explaining why I don't understand before you
answer.

I work with sound a lot. Take for instance a song from your favorite
band. In that sound you have the separate sounds of the Vocalist,
guitarist, drummer, and bassist. Once the sounds are mixed together
it becomes one waveform. Although your ears can pick up the
difference between the vocalist and guitarist, it is impossible to
separate those two sounds into their pure individual waveforms without
having on hand at least one of the original individual waveforms.

In the same respect when you look at the light from a star with a
planet orbiting around it that light is the combined light from both
the star and the planet. Without having at least one of the pure
waveforms of light from the star or the planet, how can you only
cancel out one? Are you assuming that all stars have the same
waveforms and just canceling the stars light with a generic star
waveform? Otherwise wouldn't canceling the stars light also cancel
the planets light?

The difference can also be understood for sound waves. The nulling
interferometer is designed to null all waveforms originating
in one particular _direction_, so we can see weaker waveforms
from slightly different directions. The equivalent for sound
would be measuring the total waveform from several different
places and cancelling only that portion which has the right
relative time delays to originate (say) from the monitor speaker
that has way too much synthetic drum mixed into it.

The key is that the planet's light comes from a slightly different
direction than the starlight, and one designs the nulling setup to
cancel only light from a very small region (setting the size of
the baselines) around the star, not including the search region
for planets.

Bill Keel

"William C. Keel" wrote in message ...
Albion wrote:
First of all I have gotten answers to this question from Google
Answers and HowStuffWorks and I am still confused about it.

My question is; how can you nullify the waveform from a star and be
left with the light of an orbiting planet? Now please read the
following paragraph explaining why I don't understand before you
answer.

I work with sound a lot. Take for instance a song from your favorite
band. In that sound you have the separate sounds of the Vocalist,
guitarist, drummer, and bassist. Once the sounds are mixed together
it becomes one waveform. Although your ears can pick up the
difference between the vocalist and guitarist, it is impossible to
separate those two sounds into their pure individual waveforms without
having on hand at least one of the original individual waveforms.

In the same respect when you look at the light from a star with a
planet orbiting around it that light is the combined light from both
the star and the planet. Without having at least one of the pure
waveforms of light from the star or the planet, how can you only
cancel out one? Are you assuming that all stars have the same
waveforms and just canceling the stars light with a generic star
waveform? Otherwise wouldn't canceling the stars light also cancel
the planets light?

The difference can also be understood for sound waves. The nulling
interferometer is designed to null all waveforms originating
in one particular _direction_, so we can see weaker waveforms
from slightly different directions. The equivalent for sound
would be measuring the total waveform from several different
places and cancelling only that portion which has the right
relative time delays to originate (say) from the monitor speaker
that has way too much synthetic drum mixed into it.

The key is that the planet's light comes from a slightly different
direction than the starlight, and one designs the nulling setup to
cancel only light from a very small region (setting the size of
the baselines) around the star, not including the search region
for planets.

Bill Keel

Thank you VERY much, that explains it perfectly.

-Al