Matthew

2003-Dec-19, 12:44 AM

What is the purpose of a Parsec, who named a parsec a parsec. And why is it 3.26 ly?

Thankyou.

Thankyou.

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Matthew

2003-Dec-19, 12:44 AM

What is the purpose of a Parsec, who named a parsec a parsec. And why is it 3.26 ly?

Thankyou.

Thankyou.

Littlemews

2003-Dec-19, 12:58 AM

"a non-metric unit of distance used in astronomy. As the Earth makes

its orbit around the Sun, nearby stars appear to shift their

positions in relation to the background of distant stars. The

shift, called the parallax of the star, is very small, less than

one arcsecond even for the nearest stars. If it can be measured,

however, then simple trigonometry can be used to find the distance

from the Earth to the star. One parsec is the distance at which a

star appears to shift its position by one arcsecond over the course

the time (about 3 months) in which the Earth moves a distance of

one astronomical unit (au) in the direction perpendicular to the

direction to the star. Using this unit makes it easy to compute

distances: the distance to a star, in parsecs, is simply one

divided by the amount of the parallax. If the parallax is 0.01

seconds, the distance is 100 parsecs. The length of

a parsec, divided by one astronomical unit (the radius of the

Earth's orbit) is the trigonometric function of the parallax called

the cotangent; from this relation we can compute that one parsec

equals 206 264.8 au. This is the same as 3.261 631 light years,

30.856 78 petameters (30.856 78 x 1012 kilometers), or about

19 173 510 000 000 miles."

too lazy to talk about it :P

its orbit around the Sun, nearby stars appear to shift their

positions in relation to the background of distant stars. The

shift, called the parallax of the star, is very small, less than

one arcsecond even for the nearest stars. If it can be measured,

however, then simple trigonometry can be used to find the distance

from the Earth to the star. One parsec is the distance at which a

star appears to shift its position by one arcsecond over the course

the time (about 3 months) in which the Earth moves a distance of

one astronomical unit (au) in the direction perpendicular to the

direction to the star. Using this unit makes it easy to compute

distances: the distance to a star, in parsecs, is simply one

divided by the amount of the parallax. If the parallax is 0.01

seconds, the distance is 100 parsecs. The length of

a parsec, divided by one astronomical unit (the radius of the

Earth's orbit) is the trigonometric function of the parallax called

the cotangent; from this relation we can compute that one parsec

equals 206 264.8 au. This is the same as 3.261 631 light years,

30.856 78 petameters (30.856 78 x 1012 kilometers), or about

19 173 510 000 000 miles."

too lazy to talk about it :P

Matthew

2003-Dec-19, 01:48 AM

Thankyou for clearing that up. :D

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