I apologize for not posting a version of today's APOD, because it is too large (~700 KB), and I am only allowed to post three attachments here.
Yes, but look at this wide field image of Barnard 150 (the Seahorse) set in perspective...
It looks amazing, isn't it? The Dark Seahorse is dead center, looking like a man running with one short and one extremely long leg, or perhaps like a dancing or stumbling man trailing a very long tail behind him. (Can't see the Seahorse, sorry.)
At far left is bright spiral galaxy NGC 6946 - surely you can find it. To the lower left of it is cluster NGC 6939. You can see both objects together here
. At right is the red emission nebula Sharpless 2–129, also known as the Flying Bat Nebula
, and inside it is the elongated blue nebula known as Ou4, or the Giant Squid Nebula
. Talk about an impressive neighborhood for the Dark Seahorse, right?
Anyway. The Dark Seahorse is an elongated dust lane, a concentration of gas and dust, and these things are so often elongated. A variation of the dark dust lane is the Bok Globule, which is an "island" of gas and dust inside an emission nebula, where it is being pummeled by stellar winds and harsh ultraviolet radiation, so that it - the Bok Globule - is being evaporated. This is my favorite Bok Globule:
Finger of God (or possibly a ruder finger)
in the Carina Nebula. Photo: Hubble.
Finger of God and a man hanging on to it.
Let's return to the more "normal elongated dust lanes. An interesting one is known as the Snake Nebula in Sagittarius (not to be confused with this guy
Note that the long Snake Nebula is only forming stars in a very few places. That is what star formation is like, as far as I can understand: It takes a concentration of gas and dust to form stars, which means that stars form where there is dust (and gas), but dust lanes are "barren" in most places.
To see what that means, take a look at this pair of galaxies:
A very long, curving outer dust lane in the spiral galaxy is seen in silhouette against the background light of the elliptical galaxy. A few blue spots in the dark dust reveals sites of star formation. But as you can see, most of the dark dust is "barren".
Does the Dark Seahorse of Cepheus carry any roe in its depths? Who knows?
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