and we'd have to travel over 40 trillion kilometers to get to the next star system alpha centauri but is that a distance anyone can imagine. light means over 4 years to travel that far because light always moves at the same constant speed throughout the universe astronomers can use it to define distances. they can determine how far away a star is using the stellar power locks method it involves measuring a given star's position in the night sky 6 months later they measure it again they can then calculate the star's distance to us using trigonometry but this method only works for objects relatively close to us up to a distance of about 150 light years if astronomers want to find out the dimensions of the milky way or the distance to our neighboring galaxies they have to use another measuring stick. sci fi of variables sci fi heads are thinking stars that at certain periods have a known luminosity that's why they're also known as standard candles astronomers can calculate the distance using the amount of light that reaches their telescope at specific times during a c 3 it's pulsation. s