NASA's Hubble Space Telescope captured this image of the lenticular galaxy NGC 3489. Lenticular galaxies aren't quite spiral galaxies or elliptical galaxies. They lie somewhere in between, exhibiting traits of both. Lenticular galaxies have a central bulge of tightly packed stars and a thin, circular disk of stars, gas, and dust, like spiral galaxies, but they lack arms. And like elliptical galaxies, lenticular galaxies have older stellar populations and little ongoing star formation.