StarDate

With a waiting list of more than 90,000 customers, Pan American World Airways might have needed a name change — to Pan American Out-of-this-World Airways. That’s because the waiting list was for flights to the Moon.

The list began in 1964, when a man in Austria called a travel agency and asked to book a trip. The agency referred him to Pan Am, one of the world’s leading airlines. Pan Am politely put him on a waiting list.

When word about the list got out, a few hundred others added their names to it over the next few years. But the list took off in late 1968, when Apollo 8 put the first astronauts in lunar orbit. And it got even bigger a few months later, when Neil Armstrong and Buzz Aldrin became the first to land on the Moon.

Pan Am never took money or issued reservations. Instead, those on the list became members of the First Moon Flights Club, and received a numbered membership card. The club was so popular that Stanley Kubrick featured Pan Am space shuttles in the movie 2001: A Space Odyssey. And Pan Am even promoted the club in its advertising.

The list grew so long that the airline closed it 50 years ago today. But it told those already on the list that it was still planning to send them to the Moon as soon as possible.

It was not to be, though. Pan Am went bankrupt in 1991. Members of the First Moon Flights Club were left with their membership cards — and thoughts of what might have been.

Script by Damond Benningfield

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Two planets that are a study in contrasts will cross paths in the dawn twilight the next few days. They’re fairly easy to spot from some locations, but not from others.

Mercury and Jupiter are at opposite ends of the planetary scale in just about every aspect. Mercury is the smallest planet in the solar system, while Jupiter is the largest. Mercury is a ball of rock, while Jupiter is a ball of gas. Mercury is roasted by the heat of the nearby Sun, while Jupiter gets more warmth from its own interior than from the Sun.

Much of that is a reflection of where they were born. Mercury formed close to the Sun. The Sun’s radiation and winds blew lightweight materials away from that region. That left only heavy grains of solid material to come together to make planets.

Jupiter was born much farther out, where it was colder and calmer. Solid grains came together to form the planet’s core. As the core grew, it swept up the lighter elements around it — especially hydrogen and helium, the lightest of all.

So Mercury and Jupiter became quite different worlds — a study in contrasts.

Look for them low in the east-southeast in the dawn twilight. Jupiter is the brighter of the two. Tomorrow, Mercury will stand close above it. Mercury and Jupiter will appear to almost touch each other on Friday. Mercury will move away from Jupiter after that. The planets are much easier to see from more southerly latitudes, where they rise at a better angle.

 
Script by Damond Benningfield

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Vesta is the second-largest member of the asteroid belt, but it may be the best understood. A spacecraft orbited the little world for more than a year. And pieces of it have been found here on Earth — more than 1200 of them.

On average, Vesta is about 330 miles in diameter — about half the size of Ceres, the giant of the asteroid belt. But it passes closer to Earth, and its surface is brighter, so it’s easier to see and study.

The Dawn spacecraft arrived at Vesta in 2011. It found that Vesta consists of layers of rock and metal, like a planet. It also found that liquid water once flowed across the surface, and that frozen water may lurk below the surface even today.

Dawn also discovered a giant crater at the south pole. It’s hundreds of miles across and about eight miles deep. It probably was gouged by a collision with another asteroid less than a billion years ago. Chunks of debris from the impact form a family of small asteroids.

Even smaller bits from the impact may have made it all the way to Earth. They form a class of meteorites that match Vesta’s composition. They reveal details about Vesta’s early history — helping make it the best-known asteroid in the solar system.

This is a good time to study Vesta because it’s lining up opposite the Sun. It’s in view all night, and is brightest for the year. It’s just below naked-eye visibility. Through binoculars, it looks like a faint star near the back leg of Leo, the lion.

Script by Damond Benningfield

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Until the last century, few women earned a living in astronomy. The first one to get paid for her work, in fact, didn’t receive a regular salary until 1740. And she received that only because her brother had passed away.

Christine Kirch was born in Germany around 1696 — 325 years ago. She was a member of an entire family of astronomers. Her father was the first astronomer at the Berlin Observatory. And her mother helped him make observations and create calendars — an important line of work for observatories at the time.

Christine joined the family enterprise when she was still a child, helping keep time for observations. When her father died, her brother took his post, and Christine and her mother and sister aided him. Christine, in fact, became a skilled calendar maker, and received occasional payments from the Berlin Academy of Science.

When the brother died, Christine took over his job as calendar maker, and received her first regular salary. She was especially responsible for making calendars for Silesia, a province that Prussia had just conquered. The academy had a monopoly on calendar making, so it earned a tidy income from Kirch’s work.

Kirch continued to draw a salary even after she retired at age 77. She trained her successor, Johann Bode, who would become one of the most famous astronomers in the world. Kirch died in 1782 — after 42 years as the world’s first paid female astronomer.

Script by Damond Benningfield

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Hydra, the water snake, goes on and on and on. It’s the longest of the 88 constellations. At midnight tonight, in fact, its head stands halfway up the southwestern sky, while its tail is just clearing the horizon in the southeast.

Yet the snake is hard to follow, because most of its stars are faint. The brightest one is only second magnitude. That puts it well down the list of the night sky’s leading lights.

Alphard looks so faint because it’s about 180 light-years away. In reality, it’s pretty impressive. The star is about four times the mass of the Sun, and about 50 times the Sun’s diameter. And it shines almost a thousand times brighter.

Alphard is more than 400 million years old — roughly one-tenth the age of the Sun. Because of its greater mass, though, it’s already nearing the end of its life. It’s “fused” the original hydrogen fuel in its core to make helium. Now, it’s fusing the helium to make oxygen and carbon.

Fairly soon, its core will shut down, and it will cast its outer layers into space. That will create a colorful bubble around the star’s core. The bubble will quickly dissipate, though, leaving only the now-dead core — and depriving the water snake of its brightest star.

Alphard is low in the east-southeast at nightfall, far to the upper right of the Moon. It’s a long way from the next bright star. That isolation earned the star its name: Alphard is an Arabic name that means “the solitary one.”

Script by Damond Benningfield

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About 85 percent of all the matter in the universe appears to be dark matter. Yet scientists haven’t been able to find it. But a recent study suggests a new way to look for it: by taking the temperature of many planets in other star systems.

Dark matter almost never interacts with everyday matter — the stuff that makes up stars, planets, and people. But astronomers know it’s there because it exerts a gravitational pull on the stars and galaxies around it.

Dark matter is thought to be made of subatomic particles. But every effort to find them has come up empty. So astronomers recently said that we might see them indirectly in planets near the center of the galaxy.

There should be more dark matter concentrated there than in the galactic suburbs, where we are. Some of the dark matter should interact with matter in the centers of planets. If the planets are comparable to Jupiter, the giant of our own solar system, then there could be enough interactions to make the planets hotter. So taking the temperature of giant planets across the galaxy could tell us whether dark matter really does consist of tiny particles — and what those particles are like.

Such a project would need to study more planets than we know about. But future ground- and space-based telescopes should find many more. They should also be able to measure the temperatures of those planets — perhaps helping to solve the mystery of dark matter.

Script by Damond Benningfield

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A bright star follows the bright Moon across the sky tonight: Regulus, the heart of the lion. It’s below the Moon as night falls, and closer to the left of the Moon at first light.

If the weather conditions are just right, you might see another bright companion for the Moon: a ring of light. If it’s there, it’ll be huge — it’ll extend well beyond Regulus.

Such a ring is known as a Moon ring or a winter halo. It’s caused by moonlight passing through cirrus clouds. Such clouds are thin, so you can see right through them. And they’re high — at least four miles up. They can produce halos around the Sun as well.

Cirrus clouds are made of ice crystals. The crystals are flat hexagons. They act as tiny prisms, bending the moonlight. It’s bent at a 22-degree angle, so the light forms a halo that spans 44 degrees — more than four times the width of your fist held at arm’s length.

But the crystals bend different colors of light at different angles, just as water droplets bend light to create a rainbow. So a halo sometimes shows a faint palette of colors — red on the inside of the halo, and blue on the outside.

Cirrus clouds often precede cold fronts, so a Moon ring has long been considered a sign of bad weather. There’s even a saying about it:

A ring around the Sun or Moon
Means rain or snow is coming soon.

Even if you don’t see a Moon ring, enjoy the Moon and the star Regulus as they arc across the winter night.

Script by Damond Benningfield

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Some stars just don’t know how to stay dead. Consider Sakurai’s Object. It had already “died.” But 25 years ago this week, an amateur astronomer in Japan reported that the star had flared back to life. This “rebirth” won’t last long, though — the star is already back on its earlier track.

Originally, Sakurai’s star probably was several times the mass of the Sun. It aged quickly, and puffed up to form a giant. About 8,000 years ago, it expelled its outer layers into space. Today, those layers form a faint red bubble around the star.

The expulsion left only the star’s core — a dense ball of carbon and oxygen topped by a thin layer of hydrogen and helium. It no longer produced nuclear reactions. But it was extremely hot, and a hundred times brighter than the Sun.

The core was cooling and fading, so it was on track to become a white dwarf — the final phase of life for many stars. But a quarter of a century ago, it flared up. The helium at its surface basically caught fire — nuclear fire. The helium fused to make heavier elements, causing the “dead” star to briefly flare back to life.

The outburst expelled a lot of gas into space. Some of the gas cooled and condensed to form grains of dust. For a while, the dust was so thick that it completely hid the star. But it’s thinned out, allowing astronomers to watch Sakurai’s Object settle down once more, probably for good — and complete its evolution into a white dwarf.

Script by Damond Benningfield

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Sextuplets are rare — only a couple of hundred sets have been recorded. And they’re rare among stars as well — astronomers have recorded only about a dozen of them.

The most famous is Castor, one of the twins of Gemini. It’s one of the two dozen brightest star systems in the night sky, so it’s easy to pick out.

The system consists of three sets of twins. The stars in each set are so close together that we can’t see them as individual stars, even through the largest telescopes.

Astronomers know they’re twins, though, because they see the “fingerprints” of two stars in their spectra — the breakdown of their individual wavelengths of light. As the stars orbit each other, the imprints of the two stars shift back and forth a bit.

Two of the sets of twins are almost identical to each other. Each one consists of a star that’s bigger, heavier, and hotter than the Sun, plus a star that’s smaller, lighter, and cooler than the Sun. The two systems orbit each other once every 450 years or so.

The third set of twins consists of nearly identical stars. Both are about the same as the fainter stars in the other two sets. And this pair is so far from the others that it takes at least 14,000 years for them to make a single orbit.

Castor and Gemini’s other “twin” star, Pollux, line up to the upper left of the Moon at nightfall. Pollux is closer to the Moon, and is brighter than Castor — the best-known sextuplet in the night sky.

Script by Damond Benningfield

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Like waves rippling across the ocean, the aftermath of a stellar explosion is rippling across our region of the galaxy. It forms a thin arc that runs between the big and little dippers.

Astronomers first saw evidence of the ripples in 2006. A space telescope detected a thin, straight line produced by X-rays. It was a couple of degrees long — the width of your finger held at arm’s length.

A few years ago, other astronomers followed up on the discovery. And they found that the line kept on going. It forms an arc that’s 30 degrees long — three times the width of your fist. It extends from near the outer edge of the bowl of the Big Dipper to the handle of the Little Dipper.

X-rays indicate that the arc is a shock wave — something that’s plowing through the gas and dust between the stars. It appears to be the aftermath of a supernova — an exploding star.

The explosion took place perhaps 100,000 years ago, about 600 light-years from Earth. Debris from the star’s outer layers was blasted into space at up to a few percent of the speed of light. That bubble of gas and dust continues to expand, getting thinner, cooler, and fainter. So today, all that’s visible is a long, thin strand at the edge of that expanding bubble — an arc between the dippers.

The Big Dipper is in the northeast at nightfall, standing on its handle. The Little Dipper is to the left. Its bowl hangs below the handle, which ends at Polaris, the North Star.

Script by Damond Benningfield

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