5. Although Joseph Stalin was not primarily interested in defeating Japan, what seemed to
convince him to join the Allies in this venture?

He was 'persuaded' because Hitler invaded Russia in June of 1941 and broke their non-aggression pact. Germany and Russia had signed a pact to split Poland and this started the war when the Allies declared on Germany. But when Hitler double crossed Stalin he threw his lot in with the Allies (such as they were at that point). Russia did not declare war on Japan until after the first atomic bomb was dropped on Hiroshima, and by that time the war was all but over. Stalin also knew that, near the end, he would not have to commit Russian troops to invade Japan

Explanation:

light-year  

the distance that light travels in a vacuum in one year, equal to about 9.46 trillion km (5.88 trillion mi). light-years are used in measuring interstellar and intergalactic distances.  

parsec  

a unit of distance used in astronomy, equal to about 3.25 light years (3.08 × 1016 meters).  

parallax  

the apparent angular displacement of a celestial body due to its being observed from the surface instead of from the center of the earth (diurnal parallax or geocentric parallax) or due to its being observed from the earth instead of from the sun (annual parallax or heliocentric parallax)  

absolute magnitude  

the magnitude (brightness) of a celestial object as it would be seen at a standard distance of 10 parsecs.  

apparent magnitude  

the magnitude of a celestial object as it is actually measured from the earth.  

redshift  

an increase in the wavelength of radiation emitted by a celestial body as a consequence of the doppler effect.  

the great thing about your imagination is that it doesn't have to make sense! if i were you i would be stuck in space, no communication with earth travelling around and around, you can only guess how long its been since your communication broke down. you land on an undiscovered planet, you do a scientific investigation examining the elements and conditions. you come across alien lifeforms.  

best of luck!