(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)

(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: NASAESAHubble Heritage Team (STScI/AURA)

(via APOD: 2012 May 12 - The Hydra Cluster of Galaxies)
Two very important things about this picture:
1) Only those two really big, bright, spiky things in the foreground are individual stars. Everything else in this picture is another galaxy.
2) Those two big elliptical galaxies (NGC 3311 and NGC 3309) and the blue close-to-edge-on spiral galaxy (NGC 3312) sitting between the foreground stars are the dominant galaxies in this cluster, the Hydra Cluster.
Of additional interest might be the overlapping pair of galaxies slightly above and a bit to the left of the main spiral. They’re cataloged as NGC 3314, and the whole cluster is in Abell as 1060. Hydra is one of the larger galaxy clusters nearby (within 200 million light-years of the Milky Way) and, I’m guessing, part of the Virgo Supercluster. (The Local Group, our galaxy cluster, along with Andromeda and some others, is part of the Virgo Supercluster as well. The supercluster is named for the dominant galaxy cluster, in this case the Virgo Cluster is much, much more massive than the Local Group or the Hydra Cluster.)
Image Credit & Copyright: Angus Lau

(via APOD: 2012 May 12 - The Hydra Cluster of Galaxies)

Two very important things about this picture:

1) Only those two really big, bright, spiky things in the foreground are individual stars. Everything else in this picture is another galaxy.

2) Those two big elliptical galaxies (NGC 3311 and NGC 3309) and the blue close-to-edge-on spiral galaxy (NGC 3312) sitting between the foreground stars are the dominant galaxies in this cluster, the Hydra Cluster.

Of additional interest might be the overlapping pair of galaxies slightly above and a bit to the left of the main spiral. They’re cataloged as NGC 3314, and the whole cluster is in Abell as 1060. Hydra is one of the larger galaxy clusters nearby (within 200 million light-years of the Milky Way) and, I’m guessing, part of the Virgo Supercluster. (The Local Group, our galaxy cluster, along with Andromeda and some others, is part of the Virgo Supercluster as well. The supercluster is named for the dominant galaxy cluster, in this case the Virgo Cluster is much, much more massive than the Local Group or the Hydra Cluster.)

Image Credit & Copyright: Angus Lau