The Early Universe

The following sequence of images from the Hubble Space Telescope looks progressively back in time to trace the evolution of elliptical and spiral galaxies in the early Universe.

The images are labeled with the approximate time after the formation of the Universe, with the top row corresponding to elliptical type galaxies and the bottom two rows corresponding to spiral type galaxies.

Today (Universe 14 Billion Years Old): [far left column] These are traditional spiral and elliptical galaxies that make up the two basic classes of galaxies in the current epoch, about 14 billion years after the birth of the Universe. Both galaxies in this column are a few tens of millions of light-years away and represent the current stage of the Universe's evolution.

Universe 9 Billion Years Old: [center left column] These galaxies existed in a rich cluster when the Universe was approximately two-thirds its present age. Elliptical galaxies (top) appear fully evolved but some spirals have a frothier appearance, with loosely shaped arms of young star formation. The spiral population appears more disrupted because of dynamical interactions in the dense cluster.

Universe 5 Billion Years Old: [center right column] Spiral structure appears vague and disrupted when the Universe was nearly one-third its present age. However, the elliptical galaxy (top) is still clearly recognizable.

Universe 2 Billion Years Old: [far right column] These extremely distant objects existed with the Universe was one-tenth its current age. The distinction between spiral and elliptical galaxies may well disappear at this early epoch, but the object in the top frame has the light profile of a mature elliptical galaxy. This implies that ellipticals formed remarkably early in the Universe while spiral galaxies took much longer to form.

The overall suggestion of these snapshots in time is that elliptical galaxies formed very early in the history of the Universe, perhaps growing by absorbing their neighbors and using up their gas and dust in bursts of star formation triggered by the mergers. In contrast, spiral galaxies went through a much longer period of formation, modification, and possible reformation as they were influenced by interactions with other galaxies in dense clusters.