Astronomy Picture of the Day

Explanation: Why are huge clouds of gas billowing from spiral galaxy NGC 4388? The extent of the gas clouds, over 100,000 light-years, was unexpected before the Subaru Telescope took the above image. NGC 4388 has a bright energetic nucleus and so is classified as an active galaxy. The spiral, relatively close by at 60 million light years, is a member of the nearest major cluster of galaxies: the Virgo Cluster. One hypothesis holds that the gas was stripped away as NGC 4388 made its way through the intergalactic medium of the Virgo Cluster. A competing hypothesis holds that the gas is all that remains of a smaller galaxy that was gravitationally deconstructed by the larger NGC 4388. Further observations may better determine NGC 4388's past and likely contribute to a better understanding of how galaxies evolve inside massive clusters.