StarDate

Cygnus X-1 contains the first black hole ever confirmed. And it recently recorded another first. Astronomers measured the details of twin “jets” of particles that shoot into space from its poles. The jets are firing at almost half the speed of light. And they have the power of 10,000 Suns.

The system consists of the black hole and a supergiant star. The black hole, which was discovered in 1964, is 20 times the mass of the Sun. The star is twice that mass.

The star is extremely hot and bright. It blows a thick wind of hot gas into space. The black hole captures some of the gas, which forms a swirling, super-hot disk around it. Magnetic fields grab some of the gas before it falls into the black hole, and fire it back into space through the jets.

Astronomers have seen jets from many black holes. But this is the first time they’ve precisely measured a jet’s power and speed. Those details are important because the jets can have a big influence on the surroundings. They can blow away gas and dust, preventing the birth of more stars. Or they can squeeze clouds of gas and dust, triggering the birth of stars. So the details help us understand the role of black holes in the evolution of entire galaxies.

Cygnus is in the eastern sky at nightfall. Although Cygnus X-1 is too faint to see, it’s about half way between the swan’s bill and the intersection of its body and wings.

Script by Damond Benningfield

Stars follow a life-long weight-loss program. They blow hot gas off their surfaces. Over time, the amount of material in these “winds” can add up. Heavier stars, in fact, can expel enough gas to make several stars as massive as the Sun.

An example is Antares, the leading light of Scorpius. It’s in good view tonight, to the left of the Moon as night falls.

Antares is a supergiant – one of the biggest and brightest stars in the galaxy. It’s more than a dozen times the Sun’s mass. And it’s so big that if you placed it at the center of the solar system, it would extend past the orbit of Mars.

But when Antares was born, about 11 million years ago, it was even heavier. Studies in recent years have placed its initial mass at about 15 to 17 times the Sun’s mass. Most of the difference has been blown into space on the star’s winds.

Antares has lost so much of its original weight because it was heavy to begin with. A massive star “burns” through its nuclear fuel quickly, making its core extremely hot. Radiation from the core causes the star’s outer layers to puff outward. That far from the core, the surface gravity is fairly low, so it’s easy for radiation to push gas out into space.

Antares is fated to expel even more of its mass. At the end of its life, its core will collapse, causing its outer layers to explode as a supernova – blasting most of its remaining gas out into the galaxy.

Script by Damond Benningfield

A new era in the exploration of Mars opened 50 years ago this week, when the first of two Viking landers touched down there. The probes measured the weather and the composition of the Martian rocks and dirt. They looked for evidence of life. And they gazed into the sky, showing a reddish tint for most of the day, but blue at sunrise and sunset.

That color is caused by dust in the atmosphere. The tiny dust grains are reddish brown. They scatter some of the sunlight – mostly red light, which makes the sky glow in shades of red. Depending on the time of day, the amount of dust, and other factors, the sky can range from butterscotch to apricot to bright pink.

But as the Sun rises and sets, its light passes through a much thicker layer of the atmosphere. That filters out most of the red light, making the Sun and the sky look blue.

There’s a lot of dust in the sky, and much of it floats quite high above the surface. So sunlight reflecting from the high-altitude dust extends the twilight, making the sky bright even when the Sun is well out of view.

Mars is inching higher into our morning sky. It looks like a fairly bright orange star. It’s in the east at dawn. The star Elnath – the tip of one of the horns of Taurus – stands to the left of Mars. The bull’s eye, Aldebaran, is to the right of Mars. It’s a little brighter than Mars, but about the same color – the color of the Red Planet.

Script by Damond Benningfield

One of the main goals of the twin Viking landers, which touched down on Mars 50 years ago, was to search for life. They found it. But then they didn’t. But maybe they really did.

If that sounds confusing – well, it is. Scientists have been debating the findings since the beginning – and the debate is still going on.

Viking 1 landed on July 20th, 1976, in a smooth plain north of the equator. It was the first fully successful landing. Viking 2 touched down six weeks later and 4,000 miles away.

Both landers conducted several experiments to look for life. They scooped up some of the powdery dust and dumped it into chemical laboratories for analysis.

In one experiment, they added water, nutrients, and a radioactive form of carbon. Any microbes in the samples should gobble up the nutrients and “exhale” the carbon. And that’s what appeared to happen – a sign of life.

But other experiments came up empty. They looked for organic compounds – the building blocks of life. And they found nothing. According to most scientists at the time, that ruled out the possibility of life. Instead, the positive results were interpreted as complex chemical reactions.

But many scientists continue to say the landers did find life. And over the past decade, there’s been a lively conversation about the results. So life at the Viking landing sites remains an open question.

Script by Damond Benningfield

In a field of volcanic rocks and red dunes on the planet Mars, an emissary from Earth sits quietly. Powdery dust may coat its white surface, possibly hiding the American flag and Bicentennial logo from view. Extreme cold might have cracked some of its lenses and other components. But if humans ever colonize Mars, they’ll certainly visit this relic – the first craft to successfully land on the Red Planet.

The Viking 1 lander touched down 50 years ago today. It was one of four craft in the Viking project – two landers and two orbiters. Viking 1 wasn’t the first probe to touch down on Mars. The Soviet Union’s Mars 3 had landed in 1971. But it died less than two minutes later, so it didn’t return any information about Mars.

The Viking 1 and 2 landers snapped thousands of pictures. They monitored the weather and measured the composition of the soil and atmosphere.

The landers also looked for signs of life. Their cameras saw no moving objects on the surface, and no growing plants. Chemical laboratories found no organic molecules in the soil. They did find chemical reactions like those produced by microorganisms on Earth. But scientists at the time decided the reactions were produced by the soil, not life; more about that tomorrow.

The Viking 1 lander operated for three Mars years – more than six Earth years. Scientists continue to study its findings to learn more about the intriguing Red Planet.

Script by Damond Benningfield