Question

The nearest star to our planet other than the sun , is 4.4 light year away.One light-year is the distance light travels in a year.
* HOW LONG DOES IT TAKE FOR TO REACH US?
* SUGGEST WHY LIGHT-YEAR IS USED AS THE UNIT FOR MEASURING THE DISTANCE BETWEEN DISTANT STARS AND OUR PLANET, RATHER THAN THE UNIT 'KILOMETER,

Answer 1

Answer:

Given:

The distance of the star is,=4.29 ly

We know that one light year is the distance travelled by light in one year.

1 light year = 3×10

8

×365×24×60×60

=94608×10

11

m

Therefore, the distance in 4.29 ly can be written as:

4.29 ly=405868.32×10

11

m

We know that 1 Parsec is also the unit of distance and its value is:

1 parsec=3.08×10

16

m

Now, to express the distance in terms of parsec.

4.29ly=

3.08×10

16

405868.32×10

11

=1.32 parsec

The diameter of the Earth's orbit is,

d=3×10

11

m

The angle made by the star on the Earth's orbit can be given by:

θ=

405868.32×10

11

3×10

11

=7.39×10

−6

rad

But, the angle covered in 1sec=4.85×10

−6

rad

So, the parallax in viewing the star at two different positions of the Earth's orbit:

for, 7.39×10

−6

rad=

4.85×10

−6

7.39×10

−6

=1.52"