These two stars whirl around one another in only a little more than four days, in contrast to Earth's orbit around the sun of 365 days!
(These two stars; whirl; around one another in only a little more than four days, in contrast to Earth's orbit around the sun of 365 days)
These two stars
whirl
around one another in only a little more than four days, in contrast to Earth's orbit around the sun of 365 days