The astronomical object known as Crab Nebula is thhe remnant of an exploded star. The explosion was seen by the Chinese in 1054 C.E. However, the Crab Nebula is about 3500 LY distance from the Earth In what year did the star actually explode.

Question

unklerhaukus · Answer

http://apod.nasa.gov/apod/image/0802/crabmosaic_hst_big.jpg

anonymous · Answer

i dont understand why are we including the current year when it was viewed in 1054

unklerhaukus · Answer

hmm,

unklerhaukus · Answer

if the crab nebula is 3500 [lyr] away, then light traveling from the crab nebula will take 3500 [yr] to reach earth 

so to find the year that the light left the crab nebula just take away the travel time from the  year it arrived at earth 1054 CE

1054-3500=

anonymous · Answer

im here

anonymous · Answer

2466

unklerhaukus · Answer

btw, im not sure where you got the distance to the crab nebula from because i thought it was 6500 lyr    (not 3500 lyr)

anonymous · Answer

my textbook says its about 3500 LY away

unklerhaukus · Answer

dont for get that the year will be before 0 CE    so it will be  ... BCE

unklerhaukus · Answer

(well i guess you can use that value if its in your book)

anonymous · Answer

so what was the first answer you gave because that seemed to make a lot of sense if the speed of light is pretty fast

unklerhaukus · Answer

$$s=\frac{d}{t}\qquad\implies t=\frac ds$$

$$d=3500 [\text{ly}]=3500\times c\times[\text {yr}]$$$$s=c$$
$$t=\frac ds=\frac{3500\times c\times[\text {yr}]}{c}=3500 [\text {yr}]$$


$$1054[\text{yr}]~C.E.-3500[\text{yr}]=-2446~C.E.=2446~B.C.E$$

anonymous · Answer

Ok thank you for your time and explanation.

unklerhaukus · Answer

sorry about my first post[now deleted] ( i only just woke up)

anonymous · Answer

its fine you've helped me understand with the formulas you've provided