StarDate

CLARKE: The next stage in evolution may be electronic or, if you like, mechanical, and the organic entities such as us represent an intermediate stage. And we may be superseded by the ultraintelligent machines, and they, in turn, may be superseded by perhaps pure energy, or spirit.

Although it sounds like something someone might say today, that prediction is from a radio interview in 1968. But then, Arthur C. Clarke always was a bit ahead of his time. He wrote about geosynchronous satellites two decades before they flew, and smartphones two decades before they were invented. And he penned some of the most scientifically valid science fiction ever written.

Clarke was born 100 years ago today, in England. As a boy, he built his own telescope, and was mesmerized by an early sci-fi magazine.

During World War II, he served as a radar technician. After the war, he was a writer — first of science fact, then science fiction. A 1945 article outlined a network of geosynchronous satellites. And his first sci-fi short story was published the following year, in the same magazine that had captivated him as a youngster.

Clarke’s popularity soared when he co-wrote the screenplay for 2001: A Space Odyssey, for which he earned an Oscar nomination. Clarke based that and his other stories on solid science and a sense that everything would work out in the end.

And when Clarke died, in 2008, at the age of 90, he was working on yet one more story of science and adventure.

Script by Damond Benningfield

The interview clip is from Pacifica Radio in 1968. Listen to the full interview.

Some of the earliest galaxies were small, faint “puffballs” that nonetheless contained many hot, bright stars. And astronomers at the University of Texas at Austin are using light from those galaxies to learn about a key era in the universe’s evolution.

A few hundred thousand years after the Big Bang, protons and electrons began linking up to make hydrogen atoms. The atoms had no electric charge, so they emitted no energy. The first stars and galaxies began to form then, but they were embedded within this “fog” of neutral gas — an epoch known as the Dark Ages.

By a billion years after the Big Bang, though, the gas in the early galaxies had been “reionized” — the atoms were split apart by light from hot stars inside the galaxies.

One tool for studying this process is the galaxies themselves. After the hydrogen atoms were split apart, some of them linked back up. When they did, they emitted a wavelength of light known as lyman alpha. It can be very bright, but it’s easily blocked by neutral hydrogen.

Because they’re from the early universe, the galaxies are billions of light-years away. That means their light has to pass through a lot of hydrogen on its way to Earth. If the hydrogen has been ionized, the lyman alpha passes through easily. If not, then the light is blocked. So by measuring light from galaxies at different distances, the Texas astronomers hope to find out when the universe became reionized — ending the cosmic dark ages.

Script by Damond Benningfield

A bright arrow lines up in the south and southeast at dawn tomorrow. The crescent Moon forms the arrow’s feathers, with the shaft outlined by the equally spaced planets Jupiter and Mars, to the upper right of the Moon. The star Spica forms the arrow’s tip.

Spacecraft have successfully visited the Moon and the two planets — dozens to the Moon, a couple of dozen to Mars, and almost 10 to Jupiter.

Spica, on the other hand, is a different story. It’s about 250 light-years away — millions of times farther than Mars and Jupiter. At that distance, it would take millions of years for a conventional spacecraft to reach Spica. In fact, it would take hundreds of thousands of years to reach even the closest star system.

That doesn’t mean that no one is trying to get there, though. A project called Breakthrough Starshot is working on plans to send a postage-stamp-sized craft to the Alpha Centauri system, our closest stellar neighbors. Although tiny, the craft would carry a camera, a radio transmitter, and other key equipment.

The project launched some test probes in July. They remained in Earth orbit, attached to larger satellites. They consisted of single circuit boards that measured about an inch-and-a-half on each side. They carried their own power systems, transmitters, solar panels, and sensors.

Known as Sprites, they mark a beginning in the effort to leave our own solar system — and take the first big step toward the stars.

Script by Damond Benningfield

A beautiful lineup stretches across the southeastern quadrant of the sky at first light tomorrow. It’s anchored by the crescent Moon and the nearby planet Jupiter, which looks like a brilliant star. The much-fainter planet Mars stands to their upper right, with the star Spica farther along the same line.

The Moon today is an airless world. Its only atmosphere is a few atoms, most of which were captured from the solar wind. In the distant past, though, it might have had a much thicker atmosphere — one that came from inside the Moon.

Recent research says the atmosphere was generated more than three billion years ago, when giant asteroids pummeled the lunar surface. They punched holes in the lunar crust. Molten rock oozed to the surface, creating dark volcanic plains.

This process also released a lot of gas, including water vapor. The study says these gases formed an atmosphere that was at its densest about three and a half billion years ago. At that time, it was about half again as thick as the atmosphere of present-day Mars.

Because the Moon’s gravity is weak, though, most of the air leaked out into space. But some of the water might have made its way to the Moon’s poles, where it froze inside deep craters. Those deposits could still be there, forming the layers of ice detected by orbiting spacecraft. One day, they might provide drinking water and rocket fuel for colonists — sustaining human explorers with wisps of an ancient atmosphere.

Script by Damond Benningfield

Mars and the Moon are both quite dry. But they do contain sources of water. And some recent studies have found evidence of even more water.

Scientists studied volcanic deposits on the lunar surface that contain tiny glass beads. Similar beads were brought to Earth by Apollo astronauts. Analysis showed that the beads contained high concentrations of water.

And using observations made by a satellite from India, the researchers found evidence of water in volcanic deposits scattered across the Moon. The materials probably came from the Moon’s mantle — the layer below its crust. That suggests that the mantle could hold a lot of water.

Other researchers recently found evidence for more water on Mars in observations made a decade ago. The scientists developed a technique that improved the quality of those observations. The new analysis revealed a lot of hydrogen wafting above large areas around the equator. The hydrogen could be an indication that large amounts of water ice are buried beneath the surface.

Ice had already been found beneath the surface at high latitudes. But water at the equator wasn’t expected. The scientists still have a lot of work to do, though, to confirm the new analysis.

Mars and the Moon are part of a beautiful quartet in tomorrow’s pre-dawn sky. Mars stands close below the Moon, with the star Spica to the right of the Moon. The brilliant planet Jupiter perches to the lower left. More about this lineup tomorrow.

Script by Damond Benningfield

One of the strongest meteor showers of the year, the Geminids, will be at its best on Wednesday night. The shower should sprinkle dozens of meteors into the sky per hour. And the Moon won’t interfere with the fireworks, so it should be a pretty good show.

Most meteor showers form when Earth sweeps up streams of particles shed by an icy comet. But the Geminids were the first meteor shower known to be spawned instead by a rocky asteroid.

Skywatchers have seen the Geminids for more than a century. But the shower’s source wasn’t discovered until 1983, by a small space telescope. The asteroid’s orbit around the Sun matches that of the Geminid meteor stream.

The three-mile-long asteroid leads a rough life. It orbits the Sun once every 17 months. It follows a highly elliptical path, so it both freezes and fries. At its farthest from the Sun, it’s outside the chilly orbit of Mars. When it’s closest to the Sun, though, the asteroid skirts well inside the orbit of Mercury. At that range, its surface temperature soars to more than a thousand degrees Fahrenheit. Because of that Sun-skimming flight, the asteroid was named Phaethon, after a son of the Greek Sun god Helios.

Phaethon may be a former comet that has exhausted its supply of ice. Or it could be a chip off a bigger asteroid.

Phaethon passed just 6.4 million miles from Earth on Saturday. Up next, the asteroid’s offspring will reach its peak — the beautiful Geminid meteor shower.

Script by Ken Croswell

The most visually impressive constellation in all the night sky climbs to prominence on December nights. It’s a sight you don’t want to miss.

Orion the hunter clears the eastern horizon by about 8 p.m. And it’s easy to find. Look for its “belt” of three moderately bright stars, which aims straight up into the sky as the constellation rises. It’s flanked by Orion’s brightest stars — orange Betelgeuse to the left, and blue-white Rigel to the right. And two other bright stars team up with them to complete a rectangle around the belt.

All seven of the stars that mark the rectangle and the belt look bright because they really are bright. They’re all supergiants — stars that are much bigger and heavier than the Sun, and tens of thousands of times brighter.

Such stars blaze through their nuclear fuel in a hurry, so they live short lives — tens of millions of years, compared to billions of years for a star like the Sun. And when such a star expires, it blasts itself to bits as a supernova.

Even more giants are being born in the Orion Nebula. It’s in Orion’s sword, which extends to the lower right of the belt. The nebula looks like a faint, fuzzy star. But it’s really a stellar nursery that’s given birth to thousands of stars, with many more still being incubated. That includes several supergiants, which light up the surrounding gas and dust. They, too, will blast themselves apart — briefly adding to the luster of this amazing constellation.

Script by Damond Benningfield

With winter approaching, the Sun can seem small and remote for those at far-northern latitudes. Its feeble light doesn’t do much to warm up the shorter days.

In the distant future, though, that won’t be a problem. The Sun will be much brighter than it is now, so it’ll keep Earth toasty warm all the time. In fact, within a billion years or so, the Sun will get so warm that it’ll boil away Earth’s oceans and air, turning our planet into a cosmic cinder.

The Sun is constantly evolving. It’s “fusing” the hydrogen in its core to make helium. That process converts about four million tons of matter to energy every second, which is what makes the Sun shine.

As more hydrogen is fused to make helium, the core gets smaller and hotter. Radiation from the hotter core pushes on the Sun’s outer layers, causing them to puff up, making our star even brighter. Astronomers estimate that it’s about 30 percent brighter today than when it was born four and a half billion years ago. And every hundred million years, it gets another one percent brighter still. So in a billion years, Earth will get so much solar energy that it won’t be habitable.

In about five billion years, the Sun will enter the next phase of life. It’ll puff up to giant proportions. Then it’ll start burning the helium in its core to make carbon and oxygen, and get bigger still. Finally, it will expel its outer layers, leaving only its hot but dead core, shining feebly through the cosmic night.

Script by Damond Benningfield

A giant planet that’s orbiting a Sun-like star appears to be in its final days. A recent study says the planet could disintegrate and fall into its sun in about three million years.

The system is known as WASP-12. It’s about 870 light-years away. The star is a bit bigger, hotter, and heavier than the Sun. And the planet, WASP-12b, is similar to Jupiter, the giant of our own solar system — a big ball of gas, perhaps wrapped around a solid core.

The planet and star are quite close together — just a quarter of the distance between Earth and the Sun. At that range, the side of the planet that faces the star sizzles at thousands of degrees. Some of the planet’s atmosphere is being blown out into space by the star’s wind and radiation. And the planet is warped by the star’s gravitational pull, so it’s shaped a bit like an egg, with the tapered end facing the star.

The study says the planet appears to be spiraling closer to the star. The star’s gravity could soon rip the planet apart. And the remains could fall onto the star in about 3.2 million years — ending the life of a planetary giant.

WASP-12 is too faint to see with the eye alone. But its constellation, Auriga the charioteer, is in good view on December nights. Right now, it’s low in the east-northeast at nightfall. It’s easy to find because its leading light, yellow-orange Capella, is one of the brightest stars in all the night sky.

Script by Damond Benningfield

Most of the stars that fill the Milky Way galaxy are in the prime of life. They are steadily “fusing” together hydrogen atoms in their cores to make helium, the next-heaviest element. In astronomical jargon, stars in that phase of life are on the main sequence — a description that comes from a simple plot of a star’s brightness and temperature.

When you plot a lot of stars, most of them lie along the same diagonal line — the main sequence. Hot, bright stars are at one corner of the plot, with cool, faint stars at the opposite corner.

One prominent star that’s on the main sequence is Regulus, the brightest star of Leo, the lion. It follows the Moon across the sky after they rise late this evening.

Regulus actually consists of two stars that are locked in a tight orbit around each other. One of the stars is well past the prime of life. But the other — the one that’s visible to the eye alone — is in its prime.

Regulus is on the bright, hot side of the sequence — it’s hundreds of times brighter than the Sun, and thousands of degrees hotter. And that tells astronomers a lot about the star. It’s several times the Sun’s mass, for example. And since heavier stars consume their hydrogen at a rapid rate, Regulus will spend a much shorter time on the main sequence than the Sun will.

So astronomers can learn a lot about what’s going on inside a star, how long it will live, and more — just by plotting the star’s place on the main sequence.

Script by Damond Benningfield