Our Milky Way galaxy of stars is so huge that
even at the speed of light it would take 100,000 years to travel
The further a star, the fainter it looks.
Astronomers use this clue to figure out the distance to very
distant stars. But there’s
a big challenge to this method: You need to know the star’s
bright it really is - to begin with.
Henrietta Leavitt discovers a way to tell the "wattage" of
certain pulsating stars by observing how long it takes them to
brighten and dim. The method opens the way to measuring distances
all the way across the Milky Way galaxy.
ABOVE: This view toward the center of our galaxy
shows the Milky Way as an immense city of stars. Our Sun and
all the stars in the night sky are its residents.