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,

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 viwing the star at two different positions of the Eart's orbit:

for, 7.39×10

−6

rad=

4.85×10

−6

7.39×10

−6

=1.52"

2 over 5

step-by-step explanation:

the 2: 3 ratio is the length of the ac segment to the cb segment total length. this implies that the ratio between segment ac length and segment ab length is 2: 5. point c is 2/5 from a to b, so the required fraction is 2/5.