(via APOD: 2012 September 14 - Elliptical M60, Spiral NGC 4647)
The Virgo Cluster has a lot of galaxies. A lot.
No, I don’t think you understand. The Milky Way is part of the Local Group. Our cluster contains us, Andromeda, and M33 as the major galaxies, all three spirals, and then about 40-some dwarf ellipticals and irregulars all gravitationally bound.
The Virgo Cluster has 3,500 galaxies. Are we in any way surprised that the local supercluster of which we are a part is known as the Virgo Supercluster? No. So, with that many galaxies, we probably shouldn’t be too surprised to see massive M60, a 120,000 light-year diameter elliptical galaxy, and NGC 4647, a 90,000 light-year diameter spiral much like our own galaxy, moving around the near edge of the Virgo Cluster on a bit of a collision course.
Should be interesting, as there’s not much more than old stars in an elliptical galaxy, but a spiral has a bunch of gas and dust that can be warped around by a gravitational encounter. That can sometimes set off a bunch of star formation (remember what we keep seeing inside of dense nebulae).
Credit: NASA, ESA, Hubble Heritage Team (STScI/AURA)