The Virgo Cluster is the nearest galaxy cluster to us; it consists of well over a thousand galaxies, many like our Milky Way, all orbiting each other due to their mutual gravity. Our Local Group, the small clump of galaxies including us, Andromeda, and a few dozen others, is actually in the suburbs of the Virgo Cluster. The center is roughly 55 million light-years away.

Messier 90 (or just M90) is a spiral galaxy that we see near the cluster center. It’s a spectacular beauty, as this Hubble Space Telescope image makes clear:

I was struck by several things looking at this image, which covers only the inner region of this galaxy. The center seems to have a lot of star-forming activity, which is given away by the clumps of blue and red regions, especially on one arm. That red is preferentially emitted by hydrogen gas in nebulae that are actively forming stars. Also, massive stars tend to be very luminous and blue, so they dominate the light of the stars actually forming.

Most spirals have dull yellow-orange centers, because star formation ceased there long ago. The blue stars don’t live long, so have died off, leaving redder stars behind. So it’s unusual to see star formation at this scale going on this close to the center.

Also, very close to the center on the left is an arc of darker material curving up and to the left. There’s a hint of material doing the same thing on the other side. My first thought was “blow out”; those massive stars blow very powerful winds of subatomic particles, like the solar wind on steroids. Also, when they die they explode as supernova, which also expels a lot of material at very high speeds. That stuff expands away and can burst through the material between the stars, creating a “popped bubble” effect because, really, that’s what they are.

But that may not be what’s happening here. M90 is moving very rapidly through the cluster, having just whipped past the center in its orbit, and is now moving away from the core. It’s moving at high velocity, and when galaxies do that through a cluster the gas and dust inside them can get stripped away by the pressure from gas between the galaxies (as I always say, it’s like opening a window in your car after your dog farts so you can clear the air). So it’s possible those arcs are actually material blown upward, out of the galaxy disk, and then is being swept back by that wind.

Also, by happenstance it’s headed in our direction. Most of the galaxies in the Virgo Cluster are moving away from us as the Universe expands; they’re undergoing a redshift. But M90 is moving toward us so rapidly it’s actually blueshifted! Not many galaxies have a blueshift; Andromeda is one. From what I’ve read, M90 is actually moving rapidly enough to escape the gravity of the cluster completely, and will eventually wander intergalactic space on its own.

If enough of its gas is stripped away it’ll stop making stars, too. Eventually it will grow redder and fainter as the luminous stars die, and only the red ones remain. That won’t be for a long time; millions of years at least, but that’s short compared to the 13 billion-year age of the galaxy. But then, that’s the fate of all galaxies as they eventually run out of gas. For the Milky Way it’ll be billions of years, but that’s still coming eventually. Some stars like red dwarfs can fuse hydrogen into helium and generate energy for trillions of years, so they’ll still be around a long time, but This Too Shall Pass. The Universe is old, but it’ll get far older, and it’s patient. What will it look like in a quadrillion years? A quadrillion quadrillion years?

Actually, I wrote a book about that.

But anyway, until then, we still have this gorgeous photo to remind us that for now, and a long long time yet to be in human terms, galaxies like M90 remain a feast for our eyes.

Those of you who have been around a while may know that I sometimes use the phrase “Holy Haleakala” as a way of showing astonishment. I don’t use it often, but back in 2010 or so Discovery Channel greenlit a limited run three-episode series called “Phil Plait’s Bad Universe”, based on my book Death from the Skies! While we were recording the show I saw something cool so I used the phrase, and my director liked it. He asked me to say it a lot, assuring me he would cut them all out except one or two. 

That director — Jay Bluemke — lied to me. OK, fine, we’re actually friends and in fact he misled me a little bit in order to tease me by putting it in the show a whole bunch of times, making me look a bit goofy. I never got back at him, but Discovery Channel canceled the show so I guess in the end the joke’s on both of us.

Anyway, the origin of my exclamatory phrase is weird: it’s from L. A. Law. Anyone remember that show? One of the characters, Douglas Brackman, has (IIRC) an on-again off-again relationship with his estranged wife, and at one point they met up in Hawai’i for a tryst. He opens the hotel door and sees her naked (off-screen). In utter awe, he mutters, “Holy Haleakala”, which made me laugh very hard (plus there was a really funny sight gag right after he said it, but I’ll let hardcore fans find what that was without detailing it here).

I don’t use the phrase much anymore, but I do say it every now and again. Why mention all this now? Because the actor who played Brackman, Alan Rachins, recently died. I don’t know anything about him, except that he seemed a good actor; Brackman was the guy you loved to hate, but Rachins also made him weirdly likable in some circumstances, and that’s not an easy thing to do.

So that prompted me to reminisce a bit. I hope you don’t mind indulging me. And if there’s a lesson to this, make it this one: You never know how or when or why you’ll affect someone, and in a way that it becomes a lifelong influence. So make it a good one.

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