StarDate

Muons are handy things. The particles act as cosmic X-ray machines. They’ve allowed scientists to peer into volcanoes, pyramids, and other structures. They’ve also provided views of ocean tides and tsunamis. And in the past few years, scientists have used them to look into typhoons in Japan. The technique could help produce better forecasts for storms around the globe.

Muons are produced when cosmic rays — particles from beyond the galaxy — slam into atoms and molecules in Earth’s upper atmosphere. The collisions generate “showers” of many other particles.

The muons almost never interact with other matter. But the rare interactions they do produce can help scientists map the material they’ve passed through — from ocean water to solid granite.

Researchers set up detectors below typhoons that passed over Japan in 2016, ’19, and ’21. That revealed the three-dimensional structure of the storms. The scientists mapped warm, low-pressure air in the center of the storms, surrounded by colder, high-pressure air.

The observations were provided in real-time, offering views that weren’t available any other way. When combined with other observations, they provided some of the most complete pictures to date of what was going on inside big storms. So these cosmic X-ray machines could help scientists better understand all storms — and perhaps produce better forecasts of what they’ll do.

Script by Damond Benningfield

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The Moon is drifting away from us — at about an inch and a half per year. That’s not much, but it adds up. Billions of years ago, the Moon was much closer than it is now. And because of that, Earth’s days were much shorter.

According to a recent study, for example, two and a half billion years ago the Moon was only about 200,000 miles away — roughly 40,000 miles closer than it is now. And Earth’s day was only about 17 hours long.

The numbers are changing thanks to the tides. As the tides slosh back and forth against the land, they function as a brake, slowing down Earth’s rotation on its axis. Tides in the land contribute to the effect, as do tides in the lunar landscape. That makes the days longer. To keep the total motions of the Earth-Moon system in balance, the Moon has to move farther away.

But it’s not a smooth process — the rate of change varies. That’s caused by changes in the shape of Earth’s orbit, its tilt on its axis, and other factors. Right now, things are happening more quickly than they were a few billion years ago — causing the Moon to slide away faster than it did in the distant past.

The fat crescent Moon is in the south and southwest this evening. And it has a prominent companion — the giant planet Saturn. Saturn stands above the Moon at nightfall, and looks like a bright star. They’ll be a little farther apart tomorrow night, with Saturn to the right of the receding Moon.

Script by Damond Benningfield

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The Martian atmosphere is nothing to sniff at — or to sniff at all. It’s less than one percent as thick as Earth’s atmosphere, and it’s made almost entirely of carbon dioxide. Yet it could be a valuable resource for future explorers. They might be able to extract oxygen from it, and use it to make rocket fuel.

The Perseverance rover has already pulled oxygen from the Martian air. A small generator squeezed and heated carbon dioxide. That split the C-O-2 into carbon monoxide and oxygen atoms. The atoms were than combined to make oxygen molecules — the form we breathe.

The experiment generates as much oxygen as a small tree. The technique would need to be drastically scaled up to produce enough oxygen for several human explorers. But at least we know the technique works.

Scientists also have tested a technique for making methane from the Martian air — but only in the lab here on Earth. The methane could be used as rocket fuel. No rocket engines have yet used methane to send a craft into space. But several companies and agencies in the U.S. and elsewhere are working on them. So human explorers may be able to use the Martian air to send them on their way home.

Look for Mars all night long. The planet is low in the east-northeast as night falls. It looks like a brilliant orange star. In all the night sky right now, only the Moon and Jupiter outshine it. It climbs high overhead later on, so you can’t miss it.

Script by Damond Benningfield

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The landing site of the Perseverance Mars rover could have been quite comfortable about three-and-a-half billion years ago. The rover discovered organic compounds — the chemical building blocks of life — in sediments in an ancient riverbed. The rock layers where the compounds were found suggest the environment would have been favorable for life.

Jezero Crater is 28 miles across. And in the distant past, it was filled with water. Scientists had expected it to be paved with layers of sediment, which form as rocks and grit in the water settle to the bottom and cement together. Instead, the rover’s instruments have found that most of the rock on the crater floor was formed by volcanic processes.

Sedimentary rocks do form the river delta, which was deposited when Mars was warmer and wetter than it is today. Analysis of rocks at a formation named Wildcat Ridge revealed the organic compounds.

Perseverance will spend many months examining the delta. And it’s storing samples of the sediments for return to Earth, where scientists can check more thoroughly for evidence of ancient life.

Mars is a stunner right now. It’s passing especially close to Earth, so it outshines everything that’s currently in the night sky except the Moon and the planet Jupiter. It looks like a brilliant orange star. It’s low in the east-northeast as the sky gets fully dark, and climbs high across the sky later on.

More about Mars tomorrow.

Script by Damond Benningfield

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On Mars, visitors from Earth are like loud neighbors who refuse to settle down. On Mars, though, the noise doesn’t travel far — it fades out in a hurry.

We’re learning a lot more about how sound travels on Mars from one of those noisy visitors, the Perseverance rover. It’s been crawling across Mars for 21 months. It’s looking for evidence that its landing site could have been a comfortable home for life in the distant past.

Perseverance has two microphones — the first on the surface of any other world. And most of the time, they hear almost nothing — only an occasional sigh of wind. ...

Most of what they have heard has been the rover itself. It’s recorded the motions of its robotic arm ... a device that clears off rocks for study ... and the whir of Ingenuity, a small helicopter that hitched a ride with Perseverance. ...

It’s also recorded the clicks of a laser that zaps the rocks. ... The timing of the zaps has helped scientists learn more about how sound travels on Mars. The Martian atmosphere is thin, cold, and made almost entirely of carbon dioxide. In that environment, the speed of sound is only about two-thirds as fast as it is on Earth. High-frequency sound waves travel faster than low frequencies. But the high-end waves fade out much more quickly — letting the bass line rumble a little farther across the quiet landscape.

Script by Damond Benningfield

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The night sky brings Thanksgiving to a beautiful end, highlighted by a couple of bright trios. One is in good view as night falls, while the other is at its best later on.

As twilight fades away, the first trio forms a wide triangle in the southern sky. Its brightest point is Jupiter, about half way up in the southeast. Right now, the solar system’s largest planet is the brightest object in the entire night sky other than the Moon.

The second-brightest member of the triangle is the second-largest planet, Saturn. It’s due south, to the right of Jupiter and a little lower in the sky. It shines with a little bit of a yellowish color, which also helps it stand out.

The final member of the trio is Fomalhaut. The brightest star of Piscis Austrinus, the southern fish, is between and below Jupiter and Saturn.

The other trio climbs into good view not long after full darkness, and forms a wide arc. It’s high in the sky at midnight. Its brightest member is the planet Mars, which looks like a brilliant orange star. Only Jupiter outshines it.

The star Aldebaran is to the right of Mars at midnight, quite high in the south. It marks the bright orange eye of Taurus, the bull. Capella, the brightest star of the charioteer and one of the brighter stars in the whole night sky, is farther to the left of Mars.

These are only a few of the beautiful sights in the sky on what we hope is a beautiful Thanksgiving night for all.

Script by Damond Benningfield

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The Soviet Union’s effort to land cosmonauts on the Moon came to an explosive end 50 years ago today. The country launched its big Moon rocket on its fourth test flight. But like the first three, it ended with a giant boom.

The N-1 rocket was about the same size and weight as America’s Moon rocket, the Saturn V. Its first stage was more powerful, with more than 10 million pounds of thrust. In fact, it’s the most powerful rocket ever launched.

The N-1 also was more complicated than the Saturn. Its first stage had 30 engines. That was a lot of plumbing to go wrong. And unlike the Americans, the Soviets didn’t have the money to work out any problems in ground testing. So they had to do all their testing in flight.

And that just didn’t work out. None of first three test flights lasted for more than three minutes. One blew up just seconds after launch, destroying not only the booster but also its launch pad.

The fourth flight carried a robotic spacecraft that was supposed to fly past the Moon. 90 seconds into the flight, six engines shut down as planned. But that created a shockwave that started a fire. Seconds later, an engine exploded and the rocket broke up.

Another test flight was planned for late 1974. By then, the Americans had long since finished their Apollo missions to the Moon, and the Soviet space program was broke. So the entire lunar-landing program was cancelled — including the N-1.

Script by Damond Benningfield

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Earth will have a close call tonight. An asteroid that’s big enough to cause major damage will pass just 708,000 miles away — about three times the distance from Earth to the Moon.

2005 LW3 is classified as a potentially hazardous asteroid — one of about 2200 that we know of. Such asteroids could hit us. And if they’re big enough, they could inflict major harm.

In 2013, for example, an asteroid just 65 feet in diameter exploded high above the Russian city of Chelyabinsk. The shockwave injured about 1500 people, mostly from flying bits of glass. And in 1908, an asteroid about three times that size exploded above Tunguska, in Siberia. It flattened 500,000 acres of forest, and may have killed three or more residents.

2005 LW3 is much bigger than either of those — about 400 to 900 feet in diameter. At that size, it would either explode high in the air or slam into the ground. Either way, the blast would be the equivalent of thousands of big nuclear bombs — powerful enough to destroy a city.

Close encounters like this one are common. A much smaller asteroid passed much closer just a week ago, for example. And another big one will pass a little closer on Christmas Day.

Most potentially hazardous asteroids are small. And so far, none of them is on a known collision course. But astronomers discover new ones all the time — potentially deadly space rocks.

Script by Damond Benningfield

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A pair of supermassive black holes in the heart of a distant galaxy may be headed for an unfriendly merger. We could see them ram together in as little as three years, producing some big fireworks.

The black holes have a combined mass of roughly 200 million times the mass of the Sun. They’re in a galaxy that’s about a billion light-years from Earth. The galaxy is in the constellation Boötes the herdsman, which is dropping from view in the western sky at sunset.

Astronomers have kept an eye on the galaxy for a few years. Space telescopes found that X-rays from the galaxy’s heart go through an up-and-down cycle. Over a couple of years, the length of that cycle dropped from about a year to just three months.

A team of researchers said the peaks in the cycle could be produced as the black holes approach each other. As they do so, they kick out blobs of hot gas from the disks that encircle the black holes. The change in the timing of those peaks could mean that the black holes are pulling closer together. At the rate they’re approaching each other, they could merge in just three years. That would produce a huge outburst of X-rays and other forms of energy.

The merger also would produce an outburst of gravitational waves, which are faint ripples in space-time. No current instruments can detect the wavelengths the merger would produce, though, so they’ll remain unobserved.

Tomorrow: Lining up some close calls.

Script by Damond Benningfield

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A star that’s about to undergo some big changes highlights the head of Cetus, the whale or sea monster. It probably will become unstable, then blow its outer layers into space to form a colorful bubble.

Menkar — from an Arabic name that means “the nostril” — is low in the east at nightfall and high in the south around midnight. It’s the second-brightest star in the constellation, and the brightest in the character’s head.

Menkar is classified as a red giant. It’s far beyond the prime of life. It’s converted the original material in its core to carbon and oxygen, which are basically just sitting there. All the action is taking place in a couple of shells of material around the core. In the inner shell, helium atoms are fusing together to make more carbon and oxygen. And in the outer layer, hydrogen is fusing to make more helium.

Before long, the star is likely to start puffing in and out like a beating heart. That phase won’t last long. And at its end, the star’s outer layers of gas will slough off into space. They’ll form an expanding shell of gas and dust. It might form a simple bubble, or it might be sculpted into something else — an hourglass, a butterfly, or some other beautiful shape.

The nebula could remain visible for tens of thousands of years. After that, only the star’s dead core will remain: a white dwarf — a dense ball as massive as the Sun but not much bigger than Earth.

Tomorrow: a violent merger.

Script by Damond Benningfield

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