StarDate

The heart of the galaxy Messier 87 is a cosmic maelstrom. A disk of super-heated gas that’s hundreds of times the size of our solar system encircles a monster black hole. Gas at the inner edge of the disk spirals into the black hole, producing huge amounts of X-rays. Enormous magnetic fields channel some of the gas into powerful “jets.” It’s not a place you’d ever want to visit. But it’s a fascinating region to study from far away.

M87 is a giant elliptical galaxy. It looks like a fat, fuzzy rugby ball. It’s bigger than our home galaxy, the Milky Way. It has many more stars, and could be up to 200 times as massive as the Milky Way.

The black hole at its heart is impressive, too. It’s roughly 1400 times the mass of the black hole at the center of the Milky Way. It’s pulling in gas, dust, and other debris. That material forms a disk that’s hundreds of times wider than the orbit of Neptune, the Sun’s most-distant planet.

A recent study found that material in the disk is falling into the black hole at a quarter of the speed of light. And the black hole itself is rotating at 80 percent of lightspeed or faster. That rotation generates a powerful magnetic field. The field catches some of the infalling material and shoots it back into space. That creates a “jet” of charged particles that’s thousands of light-years long – a beam of deadly radiation from the heart of Messier 87.

Script by Damond Benningfield

A galaxy cluster is like a cosmic blender. It stirs up the galaxies and the space between them. Nothing is left undisturbed.

A perfect example is the Virgo Cluster. It consists of more than 1500 individual galaxies, centered about 55 million light-years away. Most of them are fairly small and faint. But a few are monsters – many times the size and mass of our home galaxy, the Milky Way.

The cluster’s galaxies are packed fairly close together. So the gravity of each galaxy pulls at its neighbors. That distorts the shape of some of the neighbors, making them lopsided. It also causes big clouds of gas to collapse and give birth to new stars. And it pulls many stars out of the galaxies, into the space between them. In fact, up to one-tenth of the stars in the cluster may be roaming through intergalactic space.

The cluster’s brightest galaxy is Messier 49. It was the first to be discovered, in 1771. It’s a giant elliptical, so it looks like a fat, fuzzy rugby ball. It’s much bigger than the Milky Way, and many times its mass. And a supermassive black hole inhabits its heart.

The biggest and heaviest member of the cluster is Messier 87, and we’ll talk about it tomorrow.

The Virgo Cluster is centered along the border between Virgo and Leo. That spot is low in the east at nightfall and climbs high across the sky later on. Many of the galaxies are easy targets for small telescopes.

Script by Damond Benningfield

Snow blanketed the launch pad, and the rocketeers sipped hot malted milk to ward off the chill. But the launch they conducted a century ago today turned the idea of space travel from fantasy to possibility – and provided the first small step toward the Moon.

The rocket was designed by Robert Goddard, a physics professor at Clark University in Massachusetts. Goddard was brilliant but secretive. He refused to collaborate with other scientists, and seldom even talked about his research. Instead, he
spent his time building, testing, and flying rockets.

At the time he started, all rockets were powered by solid fuels, such as gunpowder. But solid fuels are inefficient and hard to control. So Goddard built a rocket powered by liquid fuels – gasoline and liquid oxygen. It was a potent mixture that provided far more energy per pound than solids.

Goddard and his wife and assistants launched the first liquid-fueled rocket in history on March 16th, 1926. It was airborne for just two and a half seconds, and climbed just 41 feet. But it proved that liquid fuels could propel a rocket skyward.

Goddard spent two more decades experimenting with rockets. German engineers used many of his innovations in the V-2, which bombarded England during World War II. Transplanted to the United States after the war, many of these engineers developed the rockets that boosted satellites into space – and sent astronauts to the Moon.

Script by Damond Benningfield

A three-way tug-of-war isn’t a common sight – unless you look toward the constellation Leo. Three galaxies there are tugging at one another, producing some spectacular results.

The galaxies are M65, M66, and NGC 3628 – the Leo Triplet. All three galaxies are about the same size as our home galaxy, the Milky Way. And each may resemble the Milky Way – a beautiful spiral with a long “bar” of stars across its middle.

The triplets are close enough together that the gravity of each galaxy exerts a strong pull on the others.

That’s given M66 a slightly “wonky” look. The galaxy’s core is a little off-center. Its spiral arms are loosely wound, and they aren’t symmetrical. And the arms are lined with knots of starbirth. Some of the stars in these regions are huge. Such a star burns out quickly, then explodes as a supernova. And since 1973, we’ve seen five supernovas in M66 – compared to zero in the Milky Way.

We see NGC 3628 edge-on, so it’s hard to know its exact shape. What we do see is a lane of dark dust sandwiched between brighter layers. We also see a “tail” that’s 300,000 light-years long – three times the size of the galaxy itself. It’s a ribbon of stars pulled out by the other galaxies in their ongoing “tug-of-war.”

Leo is in the east at nightfall. The triplet is to the upper right of Denebola, the star at the lion’s tail. It’s an easy target for a small telescope.

Script by Damond Benningfield

It sounds like a toddler’s attempt to say “Friday” or, even better, a day to gorge on apple crumb or coconut cream. Alas, “Pi Day” is something completely different. It’s a commemoration of a mathematical constant that’s represented by the Greek letter pi – one of the most important quantities in science.

Pi is the ratio of a circle’s diameter to its circumference. When it’s rounded off to two digits, it’s 3.14 – the numerical equivalent of March 14th.

Astronomers use pi to calculate the volume and density of a star or planet, the details of an orbit, and much more. Other scientists use it as well.

But pi is an “irrational” number. That means that no matter how long you calculate its exact value, you never reach the end – whether you go to a thousand decimal places, a million, or rbrm eleventy-jillion. There’s never a conclusion, and no group of numbers ever repeats. Mathematicians have used various techniques to try to calculate the exact value, without success. The record so far is more than a hundred trillion places to the right of the decimal.

Trying to calculate an exact value has been an important plot point in science fiction. Any time a computer is getting too uppity, it’s commanded to calculate pi to the last digit. That impossible task overloads the computer, allowing the heroes to regain control. Whether we’ll need it to rein in A-I – well, have a slice of pie – the tasty variety – while you ponder it.

Script by Damond Benningfield