Directional Coordinates

I live in Western Washington State where over half of the year is
cloudy and rainy. Clear skies are rare most of the year. In which
case, I've never found it practical to own a good telescope and don't
have much experience with one.

However, I have read about the complex system that the astronomy
community uses, which is necessary to figure directional reference in
the universe. Like others, I have a very general idea of how it works,
but still lack much in the way of being able to think of it in a
practical manner.

It would seem that in some way a method could be devised so that any of
these coordinates might be better visualized. For us laymen, one of
many confusing things about the universe is there is no up or down --
north, east, south or west.

Knowing where the HST is located in relation to the earth at the time a
particular image is taken along with the direction the telescope is
aimed, would be very interesting for me. Earth based telescopes would
be equally as important. Still there are others who would say, "The
pictures are coming from somewhere out there and that's all I care
about."

Computer software may have already been created to show what direction
each of the various telescope images are coming from ..... ?

I've often thought that 3 dimensional software models might be designed
with the ability to show the actual aim trajectory and in some cases,
even the target of most telescopes. I'd think that this software could
be designed, so that by entering the HST and any earth based telescope
coordinates into the software program, you'd have the desired results
for that particular day.

Needless to say, a 3D model of the Solar System in combination with the
Milky Way Galaxy, the Local Group and so on would certainly help to
better envision the BIG picture of at least a very small part of the
universe.

"C" == Chuck writes:

C However, I have read about the complex system that the astronomy
C community uses, which is necessary to figure directional reference
C in the universe. Like others, I have a very general idea of how it
C works, but still lack much in the way of being able to think of it
C in a practical manner.

The most common one is right ascension and declination. The essential
element of it is not all that complicated. The sky looks like the
inside of a sphere. Imagine that the Earth were made of glass, with
the latitude and longitude lines painted on it and that there is a
powerful lamp at the center of the Earth. Then the shadows of the
longitude and latitude lines would form the lines of right ascension
and declination, respectively.

The complex part comes from the Earth's rotation, revolution, and
precession. The right ascension and declination of a star does not
change (ignoring precession, which is a slow effect), even though it
rises at different times during the year.

C It would seem that in some way a method could be devised so that
C any of these coordinates might be better visualized. For us
C laymen, one of many confusing things about the universe is there is
C no up or down -- north, east, south or west.

I think there is a constellation site that has a Java applet with the
right ascension-declination lines overlaid.

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Joseph Lazio wrote:
"C" == Chuck writes:


C However, I have read about the complex system that the astronomy
C community uses, which is necessary to figure directional reference
C in the universe. Like others, I have a very general idea of how it
C works, but still lack much in the way of being able to think of it
C in a practical manner.

The most common one is right ascension and declination. The essential
element of it is not all that complicated. The sky looks like the
inside of a sphere. Imagine that the Earth were made of glass, with
the latitude and longitude lines painted on it and that there is a
powerful lamp at the center of the Earth. Then the shadows of the
longitude and latitude lines would form the lines of right ascension
and declination, respectively.

The complex part comes from the Earth's rotation, revolution, and
precession. The right ascension and declination of a star does not
change (ignoring precession, which is a slow effect), even though it
rises at different times during the year.

Well, to be even more exact, they do change because of the stars proper
motion ... that is why we have B1950 and J2000 references ... about
every 50 years or so one needs to update the RA/DEC of local stars to
account for changes in proper motion ...


C It would seem that in some way a method could be devised so that
C any of these coordinates might be better visualized. For us
C laymen, one of many confusing things about the universe is there is
C no up or down -- north, east, south or west.

I think there is a constellation site that has a Java applet with the
right ascension-declination lines overlaid.