Is Our Galaxy One of the Oldest?

[Gold Barz]

To form, is it one of the oldest?

 

[Vast]

Yes, it appears it is.

The currently best estimate of the age of the Universe, as deduced, e.g., from measurements of the Cosmic Microwave Background, is 13,700 million years. The new observations thus indicate that the first generation of stars in the Milky Way galaxy formed soon after the end of the ~200 million-year long "Dark Ages" that succeeded the Big Bang.

http://www.eso.org/outreach/press-rel/pr-2004/pr-20-04.html

 

[Chronos]

Good link, Vast. And that should not be surprising. Large spiral galaxies like ours appear to be quite mature.

 

[Nereid]

Also note that today's MW galaxy is likely a very different critter than the one which formed soon after the Dark Ages ended. For starters, most of the stars which make us look like a spiral are very young; for seconds, we've been snacking on small fry galaxies from Day One, and we're still eating!

 

[Gold Barz]

Are "Milky-way" type of galaxies common?

 

[Astronuc]

According to http://www.astro.umd.edu/education/astro/gal/spiral.html - Spirals are not the most common type of galaxy.

Most of the galaxies we know are elliptical in shape. The largest of these elliptical galaxies may contain as many as 10 trillion stars (10 trillion solar masses) and may be as large as 100,000 parsecs in diameter. (This is comparable to the size of our galaxy - including the entire disk of our galaxy - but with about 100 times more stars. No wonder they are so bright!) Such huge galaxies are called Giant Ellipticals (an example is shown above). They are rare but spectacular. Most of the ellipticals are Dwarf Ellipticals, which have approximately a few million solar masses and diameters of about 2000 parsecs. They are low surface brightness objects. Dwarf Ellipticals generally are found in galaxy clusters or near large galaxies. from the Department of Astronomy, University of Maryland

Our neighboring Galaxy, M31 or Andromeda, is also a spiral galaxy. Both are in the Local Cluster.

Milky Way Galaxy Wikipedia

http://www.seds.org/messier/more/mw_arms.html

The Milky Way Galaxy - A Grand Design U. of Oregon

http://www.absoluteastronomy.com/encyclopedia/S/Sp/Spiral_galaxy.htm

http://www.seds.org/messier/objects.html#galaxy

also on Wikipedia -

Galaxy
List of Galaxies
Groups or clusters of Galaxies

 

[Phobos]

Spirals are not the most common type of galaxy.

Just wanted to note for clarity that, even though they're not the most common type of galaxy, spirals are not unusual. (i.e., not a rare type)