Life-changing look at Virgo Cluster of galaxies


By Tom Burns - Stargazing



My life changed forever on a starry, moonless night, on a lonely hilltop deep in Hocking Hills.

My observing partner, diehard amateur astronomer Biff Smooter, and I had decided to observe the galaxies in the Virgo Cluster that night.

I have written frequently about Biff over the years. Now, a confession. Biff is a composite of two people, Observer Biff and Astronerd Biff.

They were constant companions. They both worked in the same lab at Ohio State. I never saw one without the other nearby. Therefore, it was easy to think of them as one person.

Yet, they were as different as two people could be. Astronerd Biff was a theoretician and mathematician. His mind soared on the abstract level of theoretical physics.

He was a master telescope-mirror maker because his mind seemed to calculate the mirror’s precise surface with every stroke of the polishing tool.

Observer Biff was no slouch on the abstract level, but his mind centered on more practical concerns. Astronerd Biff made the telescope mirrors. Observer Biff used the telescopes Biff designed. In all my years of stargazing, I have never met anyone who knew the sky and all its intricate patterns with Observer Biff’s proficiency.

The duo became a trio because I was willing to do the telescope-building grunt work.

We needed a dark, dark, rural sky to view galaxies. So we loaded my newly minted telescope into my aging, rusty VW Microbus.

The telescope still gave off the faint whiff of the leftover house paint I had used to finish it, but my inexpert craftsmanship was of little importance.

I had saved a year to purchase its light-gathering mirror, the heart and soul of any telescope. The mirror was 17.5 inches in diameter, making it the largest in central Ohio for a year or two.

I had gained a new circle of friends when I set it out for the first time a couple of weeks before. Everyone wanted a look.

The Vee-dub, as I lovingly referred to it, was another matter.

It was rusted to the windows, but it still ran — barely. Problems with the steering mechanism and suspension made it an adventure to drive.

The Vee-dub abruptly died as we neared our observing site in hilly southern Ohio. (They don’t call them the Hocking Hills for nothing.)

Unfortunately, we had been climbing one of those hocking hills. More unfortunately, the emergency brake was one of the many Vee-dub elements that did not work to its optimum specifications.

The Biffs were not, shall we say, athletically inclined. Yet they gamely held the Vee-dub in place while I desperately searched the car for something to put under the wheels.

“Vapor lock,” Astronerd Biff intoned. It had been a warm spring, and the VW Microbus was prone to vapor lock. A wood block under the tire did no good. We opened the side doors and set ourselves the task of holding the car on the hill until its difficulty passed.

Four or five hours later (or so it seemed), the cursed thing finally started.

We arrived in deep twilight and immediately began the task of carrying the telescope parts up a small hill and assembling it.

Stars filled the night. In those days, no city lights polluted the southern sky where the galaxies of the Virgo cluster reside. The sky was black and full of stars. Neither tree nor building blocked the southern horizon. Perfect!

A galaxy is a collection of hundreds of billions of stars, an island universe separated from other galaxies by trillions of miles.

Galaxies typically are grouped into herds of hundreds or even thousands.

Our own Milky Way galaxy has 300 billion stars. Our sun is one of them. It is part of our Local Group, a cluster of 20 galaxies trillions of miles across.

We were out to look at another cluster of galaxies — the one found by looking in the direction of the constellation Virgo. Far beyond the stars in the constellation Virgo. Far beyond the galaxies in our local group.

I got out my star map and proposed to go to work. “No need,” said Observer Biff as he effortlessly swung the telescope toward Virgo.

Virgo is almost directly south in the early evening. If you look at a star map, you’ll see that the right section of the constellation is cup-shaped. The galaxies are found in the cup and overflowing from it.

The heart of the Virgo Cluster is called the Scorpion’s tail. It is a long stream of galaxies in the shape of a Scorpion’s stinger — dozens of galaxies in a long curved line.

You can look at perhaps 150 of the Virgo Cluster’s 2,000 galaxies by moving your medium-sized telescope a few inches. The entire cluster is stretched out in a three-dimensional space 15 million light-years wide.

The jewel in the Virgo Cluster’s crown is M87, a dim, ovoid lump of light. At a distance of 54.5 million light-years, enormousness fades to faint fuzziness.

How big is big when even the most diminutive galaxy is mind-meltingly large? Our rather average Milky Way has 300 billion stars. M87 easily tops a trillion.

Our galaxy has an inescapable artifact of its formation at its center — a gigantic black hole. It has 3.6 million solar masses squeezed down to such density that even light cannot escape its gravitational ferocity.

M87’s black hole weighs in at three billion solar masses. Counting everything — its central black hole, stars, and every stray molecule of dust and gas — M87 has enough material to make 2.7 trillion suns.

Our Milky Way is no pipsqueak at 100,000 light-years wide. M87 is 980,000 light-years wide at its longest diameter.

The Milky Way is a typical flattened spiral, like two plates put together at their rims. M87 looks more like an egg. Its stars are spread out much more evenly into a much larger volume of space.

How did M87 get its size and shape?

Nobody knows for sure, but a good bet is that M87 started as an average-size spiral. In the universe’s early days, galaxies were much closer together than they are now.

As the galaxies moved around, they often passed near or through each other. M87 may have stripped a considerable amount of material from smaller galaxies as they passed by or through M87. Sometimes it swallowed weaker galaxies whole.

Those mergers squeezed the galaxies’ gas clouds together, sparking magnificent bursts of star formation. A flurry of early star births helps to account for M87’s large number of stars. It also explains why M87 is now almost entirely bereft of star-forming clouds of dust and gas.

We saw perhaps 150 galaxies that night. I lost count at about 3 a.m.

The individual galaxies are no big deal. Each one looks like a little fuzzy patch—some round, some oval, some thin splinters of light, some even showing a hint of the spiral structure in my large ‘scope. Remember, they are just under 55 million light-years away, and a single light-year is about six trillion miles.

The effect — and it is a genuinely profound one — is in seeing them all, scores of them, in a single night. Suddenly a realization dawns. This then is the proper unit of measure, the basic structure, of the Universe: not the atom, or the star, or the galaxy composed of countless stars, but the cluster of galaxies.

On the drive home, the Biffs talked about this or that galaxy and its various characteristics. But I was uncharacteristically silent.

I thought about the vastness of the cosmos. Was it created by some immense intelligence that some of us call God? It must have taken a powerful intellect indeed to create a universe so vast and complex.

For a few hours that night, I had experienced the texture of the cosmos. In that moment of silent contemplation on the long drive home, I felt for one mind-melting moment that I had gotten a brief glimpse into the mind of God.

Who wouldn’t be changed by that?

Planet extravaganza

Get up an hour before sunrise to see a pretty lineup of four naked-eye planets. Start by looking ESE for ever-brilliant Venus, the brightest of all the planets.

Orange-colored Mars is up and to the right. Up and to the right of Mars in the southeastern sky is yellowish Saturn.

Below and to the left of Venus is Jupiter. You’ll need an unobstructed eastern horizon to see Jupiter, which is only five degrees above the horizon at about 5 a.m..

Jupiter will rise higher as twilight brightens the sky, but Mars and Saturn will fade from view. Venus will remain visible as dusk turns to day.

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By Tom Burns

Stargazing

Tom Burns is the former director of the Perkins Observatory in Delaware.

Tom Burns is the former director of the Perkins Observatory in Delaware.