Factoid of the day

Mark your calendars for the collision of the Milky Way and Andromeda galaxies! It is our closest neighboring galaxy at only 2.5 million light years away. It is the farthest away light that you can see with a naked eye from Earth (binoculars or home telescope).

Image of Andromeda Galaxy (M31) taken by Spitzer in infrared

The Andromeda Galaxy and the Milky Way are approaching one another at a speed of 100 to 140 kilometers per second (223,200–313,200mph). The collision is predicted to occur in about 2.5 billion years. In that case the two galaxies will likely merge to form a giant elliptical galaxy. Such events are frequent among the galaxies in galaxy groups. At least one scientist believes the collision could destroy the earth or hurl the Solar System out into inter galactic space.

For a general sense of the time involved, it is believed that Earth and the sun are around 4 billion years old and that the measurable universe is around 13 billion years old.