Astronomy Picture of the Day – Spiral Galaxy in Collision

Astronomy Picture of the Day

Discover the cosmos!Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2012 August 12

Spiral Galaxy NGC 4038 in Collision I

mage Credit: Data Collection: Hubble Legacy Archive;

Processing: Danny Lee Russell


Explanation: This galaxy is having a bad millennium.  In fact, the past 100 million years haven’t been so good,  and probably the next billion or so will be quite tumultuous.  Visible on the upper left, NGC 4038 used to be a normal spiral galaxy, minding its own business, until NGC 4039, toward its right,  crashed into it.  The evolving wreckage, known famously as  the Antennae, is pictured above.  As gravity  restructures each galaxy, clouds of gas slam into each other,  bright blue knots of stars form, massive stars form and  explode,  and brown filaments of dust are strewn about.  Eventually the  two galaxies will converge into one larger spiral galaxy. Such collisions are not unusual, and even our own  Milky Way Galaxy has undergone several in the past and is  predicted to collide with our neighboring  Andromeda Galaxy in a few billion years. The  frames that compose this image were taken by the orbiting Hubble Space Telescope by professional astronomers to  better understand galaxy collisions. These frames — and many other deep space images from  Hubble — have since been  made public,  allowing an interested amateur to download and  process them into this visually stunning composite.