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Today's Deep-Sky Objects: Markarian's Chain

If you're a Northern Hemisphere observer, you'll notice that at this time of year, the Milky Way isn't visible. In fact, during late-spring evenings the Milky Way roughly circles the horizon -- almost impossible to see even on a dark night -- which means the sky overhead, or close to it, is as far from the Milky Way as possible.

You may remember that the Milky Way Galaxy roughly resembles a flattened disk, much thinner than it is broad. Like most stars, the Sun stays within this disk. When you look in or near the plane of the disk, you see enormous numbers of stars, but when you look straight out of the disk -- towards the "galactic poles" -- the sky looks relatively empty.

The view there may be empty of nearby stars and nebulas, but not of objects outside the Milky Way. With fewer stars, nebulas, and other galactic material to interfere, external galaxies are much easier to see. By a curious coincidence, a very rich collection of galaxies -- the Virgo Cluster, named after the constellation most of them appear in -- exists right near the north galactic pole. More below...

The Virgo Cluster is gigantic. While the Milky Way exists within a group of about 35 nearby galaxies, the Virgo Cluster contains over a thousand. Of these, dozens are visible in a typical amateur telescope. Of the 110 Messier objects, 16 -- almost a sixth -- are in the Virgo Cluster, and several more are nearby.

The visual centerpiece of the cluster is a group of galaxies sometimes called "Markarian's Chain". This group contains 2 of the 16 Messier objects in the Virgo Cluster (M84 and M86), along with many other fainter galaxies. Markarian's Chain is easily the densest grouping of relatively bright galaxies in the sky. There are richer (more galaxies per unit sky area) groups, but they can't be seen without either very large telescopes or very dark skies.

Near Markarian's Chain is M 87, one of the largest galaxies known. It is about twice as massive as the Milky Way, which is itself a very large galaxy. In the small to medium-sized telescope, M 87 is fairly featureless, but significantly brighter and easier to see than any of the members of Markarian's Chain.

I recently observed the richest part of Markarian's Chain with a 12.5" telescope, from my suburban home location. At one point, at low power (55x), there were 4 bright galaxies and 3 faint ones visible in the same field of view. I once observed the same field with a 10" telescope from darker skies and found 8 without any real effort; I probably could have seen a few additional ones with some extra work.

For observing galaxies like this, use as much aperture as you can get, especially from the city. Even in my medium-large scope (the 12.5"), the galaxies seemed very washed-out compared to a view in an 8" or 10" telescope under dark skies. If you don't have aperture to burn, now's a good time to drive just a few miles out of town, if you can, and check out one of the largest collections of galaxies known.


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