NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger

Nighttime Sky View of Future Galaxy Merger: Present Day

This is a nighttime view of the current sky, with the bright belt of our Milky Way. The Andromeda galaxy lies 2.5 million light-years away and looks like a faint spindle, several times the diameter of the full Moon.

NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger

Nighttime Sky View of Future Galaxy Merger: 2 Billion Years

The disk of the approaching Andromeda galaxy is noticeably larger.

NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger

Nighttime Sky View of Future Galaxy Merger: 3.75 Billion Years

Andromeda fills the field of view. The Milky Way begins to show distortion due to tidal pull from Andromeda.

NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger

Nighttime Sky View of Future Galaxy Merger: 3.85-3.9 Billion Years

During the first close approach, the sky is ablaze with new star formation, which is evident in a plethora of emission nebulae and open young star clusters.

NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger

Nighttime Sky View of Future Galaxy Merger: 3.85-3.9 Billion Years

During the first close approach, the sky is ablaze with new star formation, which is evident in a plethora of emission nebulae and open young star clusters.

NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger

Nighttime Sky View of Future Galaxy Merger: 4 Billion Years

After its first close pass, Andromeda is tidally stretched out. The Milky Way, too, becomes warped.

NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger

Nighttime Sky View of Future Galaxy Merger: 5.1 Billion Years

During the second close passage, the cores of the Milky Way and Andromeda appear as a pair of bright lobes. Star-forming nebulae are much less prominent because the interstellar gas and dust has been significantly decreased by previous bursts of star formation.

NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger

Nighttime Sky View of Future Galaxy Merger: 7 Billion Years

The merged galaxies form a huge elliptical galaxy, its bright core dominating the nighttime sky. Scoured of dust and gas, the newly merged elliptical galaxy no longer makes stars and no nebulae appear in the sky. The aging starry population is no longer concentrated along a plane, but instead fills an ellipsoidal volume.