StarDate

The Moon will be full early tomorrow, so for the next couple of nights it rises around sunset and soars high overhead during the night. Tonight, it’s in the southeastern corner of Aries, near the border with the adjoining constellation Cetus.

The silvery lunar glow looks especially cold at this time of year, as the warmth of early autumn begins to give way to the chill of winter. In fact, the full Moon of November is known as the Frost Moon.

Thanks to the Apollo missions and other observations, we know today that the Moon is a dead ball of rock. The lighter portions of its surface are ancient highlands, while the dark features of the “Man in the Moon” are smooth plains of younger volcanic rock.

That’s hardly a romantic image for our satellite world. In ages past, though, the Moon was perhaps the most romantic figure in the sky. Almost every culture developed fanciful stories to explain its creation, appearance, and cycle of phases. In many of those stories, the Moon was a goddess.

In ancient Babylon, for example, the Moon was worshipped as the queen of heaven. In other cultures, it was even more important. In parts of Scandinavia, for example, the Moon goddess gave birth to the entire universe. The Moon played a similar role in the cosmology of the Iroquois.

It’s easy to envision the Moon’s power in these and many other cultures on long, chilly nights, when the full Moon casts its “frosty” light on the landscape — all night long.

Script by Damond Benningfield

When the Juno spacecraft made its first pass above the south pole of Jupiter this summer, it took pictures of the brilliant aurora — the giant planet’s own “southern lights.” But it also listened to the lights. Its instruments detected radio waves produced by the charged particles that create the aurora. Scientists sped up those observations, and converted them to sound. [SFX: Jupiter aurora]

The aurora is produced by the interaction between Jupiter’s atmosphere and the solar wind — a steady stream of charged particles from the Sun. The particles are funneled toward the poles by Jupiter’s powerful magnetic field. They knock electrons off atoms in the upper atmosphere. When the electrons stick to other atoms, they emit light.

Some of the electrons spiral through the magnetic field, producing radio waves — the waves detected by Juno.

Earth produces its own aurorae, although you have to be in the right place to see them. From the United States, the best views generally come from Alaska and places like Maine and Minnesota.

But you can see Jupiter from just about any place on the planet. It stands low in the east-southeast at first light, and looks like a brilliant star. In fact, it’s the brightest object in the sky at that hour other than the Moon, so it’s hard to miss.

Script by Damond Benningfield

The first starship won’t look anything like the U.S.S. Enterprise. In fact, you might need a magnifying glass just to see it. But if a new project pans out, it might be possible to launch such a tiny probe to a nearby star system within decades.

Breakthrough Starshot is a 100-million-dollar project funded by Yuri Milner, a Russian billionaire named for Yuri Gagarin, the first man in space. It’s the second big space project funded by Milner; the first, which began early this year, is a search for extraterrestrial intelligence.

Breakthrough Starshot is looking at ways to launch a probe that would weigh no more than a few grams. Advances in microelectronics might make it possible to make a starship-on-a-chip — a combination of camera, power supply, and communications all on a small semiconductor.

The probe would be propelled to the stars not by its own engines, but by a giant array of lasers on or near Earth. The lasers would aim at a small, thin sail attached to the probe. Within minutes, the lasers could accelerate the craft to perhaps 20 percent of the speed of light. At that speed, the probe could reach the nearest exoplanet, Proxima Centauri b, in just a couple of decades.

None of this will be easy to develop, though. Among many other challenges, it requires big advances in electronics, lasers, and interstellar communications. But it may represent our best chance to reach the stars anytime soon.

Script by Damond Benningfield

15 years ago, an astronomer used a radio telescope in Ukraine to beam a concert to a star near the Big Dipper. The music included works by Vivaldi and Gershwin, as well as the Russian folk song Kalinka-Malinka — all played on the Theremin, an instrument best known for its role in spooky movies. It’ll take another 30 years for the concert to reach its target.

The message is one of several beamed to other star systems over the past four decades. The first was aimed at M13, a star cluster about 25,000 light-years away. And one of the most recent included hundreds of text messages from people across the planet.

The messages are part of a field known as METI — messaging extraterrestrial intelligence. Most efforts to make contact have been small and quick, and they have little chance of actually being picked up by other civilizations.

Scientists and others are debating the wisdom of announcing our presence to the universe at all. Some, including Stephen Hawking, warn that drawing attention to ourselves could lead to an alien invasion. Others argue that we already send out so many powerful radio signals that we can’t hide our presence, so we might as well try to talk to anyone who’s out there.

The debate also touches on questions of who should do the talking, and what any messages should say. For now, though, it’s mostly academic — there are no big plans to speak to the rest of the galaxy.

We’ll talk about plans to visit the galaxy tomorrow.

Script by Damond Benningfield

Kepler space telescope has revealed an amazing array of planets in other star systems. But what may be its most intriguing discovery isn’t a planet at all. In fact, scientists still aren’t certain just what it is.

It’s in a star system known as Tabby’s Star, after the leader of the team that studied it, Tabetha Boyajian.

Kepler discovers a planet by watching it “transit” in front of its star, blocking a small fraction of the star’s light — usually no more than one percent. But the light from Tabby’s Star dipped by as much as 22 percent. And there were many other drops that weren’t as deep, but that lasted for days instead of the hours required for most planet transits. Boyajian’s team wrote that the dips could be produced by a swarm of dusty comets in a lopsided orbit around the star.

One other possible explanation, though, is massive structures built by a super-civilization. Such structures could be designed to capture the star’s light to power the civilization.

Follow-up observations by other telescopes haven’t found anything to support that idea. There’s no infrared glow, which would be generated as the structures heated up. And there’s no evidence of radio transmissions from the system.

But the comet idea doesn’t work especially well, either — there’s no evidence of such swarms in any other star systems, for example. So the nature of Tabby’s Star is still a mystery.

More about the search for other civilizations tomorrow.

Script by Damond Benningfield

Using two of the world’s largest radio telescopes, plus a planet-hunting optical telescope, a team of astronomers is trying to eavesdrop on conversations between planets in other star systems, or catch the broadcasts of a “Galaxy Wide Web” that links multiple stars. The team also is listening for possible greetings transmitted our way by some of those neighbors: extraterrestrial civilizations at least as advanced as our own.

Breakthrough Listen is a 10-year, 100-million dollar project funded by Yuri Milner, a Russian billionaire.

The project will receive 20 percent of the observing time on giant radio telescopes in West Virginia and Australia, providing a view of the entire universe.

Breakthrough Listen is 50 times more sensitive than earlier programs. It’s listening for signals from the nearest million stars. Many of the stars are close enough to allow the telescopes to detect not just the greetings that other civilizations might beam our way, but the whine of military radar, communications between star systems, and even tightly beamed signals between planets within a single system.

The telescopes also monitor the densely packed center of the Milky Way galaxy, as well as a hundred other galaxies.

In addition to its “ears,” the project also has an “eye” on the universe: an optical telescope in California, which will search for interstellar lasers — one more way to track down ET.

More about the search for ET tomorrow.

Script by Damond Benningfield

The recent announcement that our closest neighboring star has a planet set off a lot of speculation about life. Proxima Centauri b is a bit bigger than Earth. Most important, it lies inside the habitable zone — the distance from the star where temperatures are just right for liquid water. That means conditions could be comfortable for Earth-like life.

So far, though, we have no evidence of any life on Proxima Centauri b or anywhere else beyond Earth. But that hasn’t stopped astronomers from looking. In fact, they’ve been hunting for signals from other civilizations for more than half a century.

The hunt is known as SETI — the search for extraterrestrial intelligence. It mainly uses radio telescopes to listen for messages beamed into space by other civilizations, or for the high-powered signals of military radar or similar technology.

Most of the searches done so far have listened to a limited number of radio frequencies, or they’ve operated for a fairly short amount of time. But a new search will examine a wide range of frequencies for several years; more about that tomorrow.

Other SETI techniques are also coming online. Some are looking for high-powered lasers, for example. Others are looking for odd dips in a star’s light that might be caused by artificial structures passing in front of it.

These and other techniques may help us find if we have neighbors elsewhere in the galaxy — or if we travel through the vast Milky Way alone.

Script by Damond Benningfield

Although the Sun is a star, it differs from most of the other stars in the galaxy in two key respects. First, it supports the only known civilization in the universe: us. And second, it’s bigger and brighter than most other stars — only a few percent of stars have about the same color, temperature, and luminosity as the Sun. But based on our example, Sun-like stars may be the best places to find planets that host intelligent life.

Two such stars orbit each other in Cygnus, the swan, which looks like a giant cross. This double star, 16 Cygni, is just 70 light-years away — quite close as stars go — but it’s just barely visible to the unaided eye. One of the stars even has a planet, although it’s much larger than Earth.

Kepler Space Telescope measured each star’s brightness every minute for two and a half years. It detected small oscillations similar to those in the Sun. These oscillations change as stars age, so the observations reveal 16 Cygni’s age: seven billion years — about half-again the age of the Sun.

At that age, if either star has an Earth-like planet, there’s probably been enough to time for it to develop advanced life.

No one has ever detected radio signals from any residents of 16 Cygni, though, so its planets may have no life at all. Or perhaps, given how old the star is, life there may be so advanced that it regards us Earthlings as primitive — and not worth talking to.

More about the search for other civilizations tomorrow.

Script by Ken Croswell

For the last couple of decades, NASA’s mantra for exploring Mars has been “follow the water.” Since water is a critical ingredient for life, one of the main goals for most Mars missions has been to find evidence of water, past or present. The water can then tell us where conditions are comfortable for life today, or where they might have been comfortable in the past

But following the water can be a lot easier said than done. Consider small “gullies” found on the slopes of craters and other features.

Early studies suggested these features were formed by flowing water. The idea was that water in underground chambers might gush to the surface during spring and summer, when conditions are warm, and rush downhill, carving the gullies. The water wouldn’t stick around, though; in the thin Martian atmosphere, it would quickly boil away.

But more recent studies suggest otherwise. They found that the gullies probably are formed not by flowing water, but by carbon dioxide frost. The C-O-2 freezes on the surface when conditions are cold, and vaporizes when it warms up.

There’s still plenty of evidence of water in other places on Mars — frozen in the polar ice caps and beneath the surface, for example. Yet the Martian gullies appear to have come up dry.

Look for Mars in the evening sky right now. The planet looks like a fairly bright orange star. It’s especially easy to find tonight, because it stands close to the left of the crescent Moon.

Script by Damond Benningfield

A galaxy that’s 13 billion light-years away is helping us understand when the lights in the universe were switched back on. And that can help reveal when the first stars and galaxies were born.

A team of astronomers used one of the giant Keck telescopes in Hawaii to study some galaxies that appeared to be young, bright, and far away. Even with this large telescope, though, they were able to measure the distance to only one galaxy. It’s so far away that we see it when the universe was only about 700 million years old. That makes it one of the earliest galaxies in the universe.

Such galaxies formed as the gravity of clumps of dark matter pulled in gas. The gas then clumped together to make stars and galaxies.

Before these objects were born, the universe was dark. A few hundred thousand years after the Big Bang, the “soup” of energy and particles had cooled enough to form hydrogen atoms, which have no electric charge. The atoms emitted no radiation, and they had not yet come together to make stars, so there was nothing to emit light.

By the time the distant galaxy had formed, though, that was changing. Not only did the early galaxies shine brightly, but their light split the electrons from the hydrogen gas between galaxies — a process known as reionization.

It took a few hundred million years to complete that process. So the 13-billion-year-old galaxy was one of the earliest around — one of the first bright lights in the universe.

Script by Damond Benningfield