08/25/2020 – Ephemeris – The Great Andromeda Galaxy will collide with the Milky Way someday

This is Ephemeris for Tuesday, August 25th. Today the Sun will be up for 13 hours and 33 minutes, setting at 8:30, and it will rise tomorrow at 6:58. The Moon, at first quarter today, will set at 12:26 tomorrow morning.

Stars are at extreme distances compared to their sizes, even if one includes their planetary systems. Galaxies in a galaxy cluster are much closer with respect to their size. Astronomers have determined that our Milky Way galaxy will collide with the Great Andromeda galaxy, some two and a half million light years away, in about four and a half billion years. Don’t worry, it is very unlikely that any stars will collide during the event, though the solar system may be in for a wild ride. As the galaxies approach each other their beautiful spiral structures will begin to distort into tidal tails. Multiple passes of the two will occur before they will coalesce into one large elliptical galaxy. Other galaxies of the Local Group will join in over time.

The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Colliding galaxies. Note the tidal tails. Credit: Hubble Legacy Archive, ESA, NASA.

Original caption: This illustration shows a stage in the predicted merger between our Milky Way galaxy and the neighboring Andromeda galaxy, as it will unfold over the next several billion years. In this image, representing Earth’s night sky in 3.75 billion years, Andromeda (left) fills the field of view and begins to distort the Milky Way with tidal pull. (Credit: NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger)