Charting
Remote Space
The
arrows in this image of a distant galaxy are pointing to
cepheids
,
stars that dim and brighten over a period of a few days. The
length of a cepheid’s blinking cycle can tell us the distance
to the cepheid--and therefore, to its home galaxy. As a result,
astronomers rely on cepheids as important distance yardsticks
in remote areas of the universe where measuring distance is
not otherwise possible. By viewing cepheids far more remote
than ground telescopes can, Hubble is helping scientists measure
the distance to increasingly remote galaxies, like the one pictured
here, 108 million light years away. Such long-distance measurements
are critical to determining the
age
and expansion rate of the universe.
