A week or so ago I sent a brief letter to mister Phil Plait, aka the Bad Astronomer. I read his blog about every day and it’s almost always got something of interest to me. The letter was:
I keep thinking about something you said on Bad Astronomy. You were talking about the Orion Nebula, saying how it’s so large and vibrant that it would stand out to observers from another galaxy who were looking at the Milky Way. That got me thinking: are there large nebulae in other galaxies that we can see, as ‘standout’ features? The biggest picture I’ve ever seen of another galaxy was Andromeda, and I looked for an equivalent of M42 in M31, but I didn’t spot much. Are there any well known examples of large beautiful nebulas in other galaxies?
And he replied:
Actually, yes. Look online for image of the Large Magellanic Cloud, which is lousy with nebulae. Also NGC 604 in the Triangulum Galaxy. One of my favorites!
So let’s look at those things he recommended! We’ll start with NCG 604. Since this one is actually located inside of a distant galaxy, I think it qualifies best as what I was originally thinking of. First off, check out this sweet 25 hour “amateur” capture of the whole Triangulum Galaxy:
If you didn’t spot NGC 604 already, it’s the large pinkish area straight below the two large yellow stars at the top of the picture. The appearance of NGC 604 seems to vary a lot depending on what wavelengths you look at. This one from Hubble is my favorite:
I did a little reading based off Phil’s suggestions and found out that all the Nebulae I’ve been digging are called H II regions, for those who are ‘in the know’. As you might guess, this name refers to a concentration of ionized hydrogen gas, H2. Get the full lowdown on wikipedia, it’s a good read. But back to the gawking. Checking out the Large Magellanic Cloud, the biggest standout Nebula is the Tarantula, which is actually the most active starburst region in our local group of galaxies. Accordingly, it’s mondo-luminous. If the Tarantula Nebula were as close to Earth as the Orion Nebula, it would shine as bright as the full moon in the night sky. Think about that! It would cast shadows; you could possibly read by that light at night. Jeez.
Also really sweet in the LMC is LH 95, another incredible-looking nebula where stars are being born.
Just for a little perspective, here are some distances:
Large Magellanic Cloud: 160 thousand light years (w/ Tarantula Nebula NGC 2070)
Andromeda Galaxy (M31): 2.6 million light years
Triangulum Galaxy (M33): 3 million light years (w/ NGC 604)
Far out, maaaan. It’s cool to check out those starburst regions as parts of other galaxies. A brief blurb from wikipedia worth repeating:
From a viewpoint in the LMC, the Milky Way would be a spectacular sight. The galaxy’s total apparent magnitude would be -2.0—over 14 times brighter than the LMC appears to us on Earth—and it would span about 36° across the sky, which is the width of over 70 full moons. Furthermore, because of the LMC’s high galactic latitude, an observer there would get an oblique view of the entire galaxy, free from the interference of interstellar dust which makes studying in the Milky Way’s plane difficult from Earth. The Small Magellanic Cloud would be about magnitude 0.6, substantially brighter than the LMC appears to us.
One more to leave you with, N90, in the Small Magellanic Cloud:
If you dig this, then check out what else awaits under the cosmology tag.