Tag: light year

Andromeda galaxy is the nearest galaxy to our Milky Way. It is about 2.537 million light-years away.

The velocity of the light is precisely 299792458 metres per second or 3 x 10$^8$ m/s.

Heavenly bodies are very far away from each other. It is impossible to measure their distances by using conventional units like miles and kilometres. Hence light year is used to measure the distance of heavenly bodies from each other.

Our Sun is the nearest star to the Earth. After the Sun, the next nearest star is 4.3 light years away. A light year is the distance light travels in one year. One light year is 10 trillion kilometers. Hence, all the stars are not the same distance from our Earth. They are at different distances. Hence, given statement is false.

$\dfrac{\triangle v}{v}=\dfrac{V _{radiant}}{C}$
$v=\dfrac{C}{\lambda}$
$d.v=\dfrac{C}{\lambda^2}.dv=\dfrac{\dfrac{x}{\lambda^2}}{\dfrac{C}{\lambda}}=\dfrac{d\lambda}{\lambda}$
$\dfrac{d\lambda}{\lambda }=\dfrac{V _{radial }}{C}$
$\dfrac{5 \times 10^{-10}}{6563 \times 10^{-10}}=\dfrac{C _{radial}}{3\times 10^8}$
Calculate $V _radial=\dfrac{5}{6563}\times 3\times 10^8$
$=\dfrac{15}{6563}\times 10^8$
$\dfrac{15}{6.56}\times 10^5$
$2.29\times 10^5m/s$

One light year is the distance travelled by the light in one year. So,

The diameter of milky way is about ${ 10 }^{ 5 }$ light years