Galaxies

A galaxy is a vast island of stars in the Universe, containing millions or billions of stars together with gas, dust and dark matter. Galaxies come in different shapes and are classified by their morphology, mainly as spiral, barred spiral, elliptical, lenticular or irregular galaxies. Their appearance reflects their structure and, to some extent, their evolutionary history. Located far beyond the Milky Way, their light may travel for millions or even billions of yearsbefore reaching us.