StarDate

In their quest to deliver packages almost before you order them, some companies are looking at using drones — small aircraft that could buzz right up to your front door. But those aren’t the first efforts to speed the delivery process with small flying machines. In the 1930s, for example, several engineers in Europe worked on delivering mail with rockets.

One of them was Reinhold Tiling, who was born in Bavaria 125 years ago today. He studied engineering, then became a pilot in the German army during World War I. After the war, he heard a lecture by Hermann Oberth, a leading expert in rockets and space travel. Inspired by the talk, Tiling soon began his own experiments.

By 1931, he’d launched several rockets, with the most successful climbing to more than a mile in altitude. And that April, he launched a rocket for the post office.

The rocket was only a few feet long. It took off from an island off the coast of Germany. When its engine shut down, a pair of wings unfolded, allowing it to glide to the mainland. Its payload of 188 postcards arrived safely. Tiling predicted that rockets would carry mail all the way across Germany, and even across the Atlantic to the United States.

That and other experiments made Tiling a bit of a celebrity. But in 1933, he and two colleagues were working on a batch of rocket fuel in his lab when the fuel exploded. All three of them were killed — ending one of the decade’s efforts to deliver mail by rockets.

Script by Damond Benningfield

Dark matter just keeps getting darker. Although we see evidence of it throughout the universe, scientists have not yet figured out what it is. So they’re expanding their searches — and their ideas.

Dark matter appears to make up about 85 percent of all the matter in the universe. It produces no detectable energy. But it reveals itself by exerting a gravitational pull on the visible matter around it. In particular, we see its influence on most galaxies and clusters of galaxies. The dark matter acts as a sort of cosmic “glue” — its gravity holds the galaxies and clusters together.

For a long time, the leading idea has been that dark matter consists of WIMPs — particles that are many times heavier than a proton. These particles would seldom interact with any form of matter, including other WIMPs. Yet despite years of searching, with ever-increasing sensitivity, scientists haven’t found a single one. They’re still looking, but they’re also thinking about other possibilities.

One is called SIMPs — particles that are less massive than a proton. They’d be an unusual form of matter, and they would interact with each other more often than WIMPs would. Scientists are trying to produce them with the Large Hadron Collider and other particle accelerators.

They’re also looking for particles called axions — particles that are even lighter than SIMPs.

So far, though, dark matter remains elusive — it’s still a dark mystery.

Script by Damond Benningfield

The surface of the planet Venus may move. It’s not like the surface of Earth, where the crust is made of thin “plates” that slide past and over each other. But there’s evidence that big chunks of Venus’s crust are moving.

Until recently, the consensus has been that Venus has a solid crust — a single structure that wraps around the planet like the skin of an apple.

But a team of geologists recently took a closer look at Venus’s surface. The team used maps compiled from observations made by an orbiting spacecraft, which peered through Venus’s unbroken cloud cover with radar.

The scientists found that blocks of the crust appear to have moved — they’ve slipped sideways, twisted to the side, or even turned around. These blocks are typically bounded by ridges or canyons that can be tens of miles wide and hundreds of miles long.

The researchers suggested that parts of the crust might be pushed and turned by motions in the layer of molten rock below the crust. That makes Venus’s surface a lot more active than scientists had thought — a surface that’s on the move.

And Venus itself is on the move, too. Our closest planetary neighbor is climbing a little higher into the evening sky each night. Tonight, the brilliant “evening star” lines up with the twins of Gemini. The stars are to the right of Venus. The brighter star, Pollux, is closer to Venus, with Castor farther along the same line.

Tomorrow: What’s the matter with dark matter?

Script by Damond Benningfield

Any residents of a galaxy in the constellation Serpens have a big problem: They’re being blasted by a death ray from a black hole.

The galaxy is a companion to a larger galaxy, known as 3C321. They’re more than a billion light-years away.

A supermassive black hole inhabits the heart of the larger galaxy. It’s surrounded by a large disk of gas that’s heated to millions or billions of degrees. Powerful magnetic fields funnel charged particles from the disk into jets. They fire away from the poles of the black hole at almost the speed of light.

One of those jets is firing toward the companion galaxy, which is just 20,000 light-years away. Observations by telescopes on the ground and in space show that the jet is hitting the edge of the companion, creating a hotspot. The encounter deflects the beam off its original course, but it continues for hundreds of thousands of light-years.

The particles and radiation in the beam could destroy the ozone layer of any planet the beam hits. That would leave the planet exposed to radiation from the beam itself, and from other cosmic sources. So anything living on the planet would be in extreme danger.

And the situation is getting even worse. The smaller galaxy appears to be just entering the black-hole jet. Over time, more of the galaxy will pass across the jet — possibly exposing even more planets to the death ray from another galaxy.

Script by Damond Benningfield

The sky is divided into 88 constellations. Actually, though, it’s more like 88 and a half. That’s because the constellation Serpens consists of two disconnected parts — a head and a tail. They’re separated by the serpent bearer as they wrap behind his body.

Serpens is in full view in the east and southeast by a couple of hours after sunset. The half that represents the head is highest, above Ophiuchus, with the tail below the serpent bearer.

The front half of the snake, Serpens Caput, is the more prominent one. It has several stars that are fairly easy to see. The brightest is Alpha Serpentis, also known as Unukalhai — “the serpent’s neck.” It’s a red giant — an old, bloated star that’s much bigger and brighter than the Sun. Its surface is much cooler than the Sun’s, so the star looks yellow-orange.

The back half of the snake, Serpens Cauda, is tougher to spot. Its brightest star, Eta Serpentis, is actually the second-brightest star in the whole constellation. It’s about half as bright as Alpha. But the two stars are quite similar. Eta is also a giant — a puffed-up star that’s nearing the end of its life. It’s not as far along as Alpha, though, so it’s not quite as big or as bright. But as it evolves, it’ll get much bigger and brighter than Alpha.

And the stars will end their lives in the same way. Each will cast its outer layers into space, leaving behind a hot but tiny corpse known as a white dwarf.

More about the serpent tomorrow.

Script by Damond Benningfield

A star cluster that was “discovered” several times climbs the eastern sky this evening. IC 4665 is a quarter of the way up the sky as it gets good and dark. It’s to the lower right of the brightest star of Ophiuchus the serpent-bearer.

Under really dark skies, the cluster is just visible to the unaided eye. It looks like a hazy patch of light a bit bigger than the full Moon. So people had actually seen it since they first looked into the night sky.

What astronomers discovered was the nature of this hazy object: a cluster of stars.

It was first recorded by Philippe Loys de Chéseaux, around 1745. There were no scientific journals in which to publish discoveries, though. Instead, astronomers let others know about them at meetings of scientific societies, or in letters. Chéseaux didn’t do that, though, so his discovery wasn’t known until much later.

By then, the cluster had been discovered twice more. Johann Bode found it in 1782, but he didn’t share the discovery, either. And the next year, it was discovered by Caroline Herschel. But she didn’t record it in her catalog of star clusters, so it still wasn’t publicized.

In fact, it wasn’t listed in any catalog until the early 1900s, when it was recorded by Harvard College Observatory.

Today, we know that IC 4665 contains a hundred or so stars. It’s at least 1200 light-years away. And it’s no more than 40 million years old — a young family of stars that kept getting discovered.

Script by Damond Benningfield

Barnard 68 is one of the darkest objects in our region of the galaxy. It’s a small cloud that absorbs the light of the stars behind it, so it looks like a dark “hole” in the Milky Way. In a couple of hundred thousand years, though, that void may shine with the warmth of newly forming stars.

Barnard 68 is a Bok globule — a small, dark sphere of gas and dust. It’s about 500 light-years away, half a light-year wide, and about three times the mass of the Sun. It’s part of a complex of dark clouds that stands in front of the glowing band of the Milky Way.

Because Barnard 68 is so dark, it’s also quite cold — temperatures at its center are not far above absolute zero. But that may be about to change.

The globule has been stable for millions of years. But there’s evidence that it’s recently been hit by a cosmic “bullet” — a smaller clump of gas and dust. That appears to be causing Barnard 68 to collapse.

As it collapses, the cloud will get denser and hotter, and perhaps split into several smaller clumps. Within a couple of hundred thousand years, the clumps could be well on their way to becoming new stars — glowing balls of gas born from a dark “hole” in the Milky Way.

Barnard 68 is in Ophiuchus, the serpent bearer, which is in the east and southeast this evening. The Milky Way runs through a corner of the constellation. Several clouds darken the Milky Way — the birthplaces of future stars.

More about Ophiuchus tomorrow.

Script by Damond Benningfield

Some of the most interesting objects in the constellation Ophiuchus look like dark holes in the sky. But they’re not holes at all. Instead, they’re immense clouds of cold gas and dust. They absorb the visible light of the stars that line up behind them, so they look almost black.

Several of these clouds group together to form the Pipe Nebula, which resembles a pipe. It has a “bowl” on the left, complete with curls of smoke, and a “stem” on the right.

Like most dark nebulae, the pipe appears to be giving birth to new stars — but not many. The only confirmed stellar embryos are found along a filament of gas in the stem. That suggests that the nebula is quite young, so it hasn’t had time to make many stars. That gives astronomers a chance to observe the very first steps in the birth of stars.

The little star formation that is going on may be triggered by a nearby group of young, massive stars. They blow strong winds that compress one of the clouds that make up the nebula. As the gas and dust smash closer together, they form clumps that collapse to make stars — bright offspring of a dark cloud.

And under especially dark skies, the Pipe Nebula is visible to the unaided eye. It climbs into good view in late evening, surrounded by the subtle band of the Milky Way. The nebula is between the bright planet Saturn, to its lower left, and the orange star Antares, a little closer in the opposite direction.

We’ll talk about another cloud tomorrow.

Script by Damond Benningfield

 

A star system in the constellation Ophiuchus, which is in the east on June evenings, can’t keep quiet. It pops off every decade or two. In just a day, it grows tens of thousands of times brighter. But those outbursts may be only the prelude to a bigger one: The star may blast itself to bits as a supernova.

RS Ophiuchi is a binary — two stars locked in a mutual orbit. One of the stars is a white dwarf — the corpse of a star that was once like the Sun. The other star is a red giant — a star near the end of its own lifetime. It’s puffed itself up so that it’s much bigger and brighter than the Sun.

The stars are so close together that the white dwarf “steals” gas from the red giant. The gas forms a disk around the white dwarf before it spirals onto the dead star. The white dwarf’s gravity squeezes this new layer of gas. Material at the bottom of that layer gets so hot that it triggers a nuclear explosion. That blows some of the top layer into space, causing the system to flare up. The last outburst appeared in 2006, with RS Ophiuchi getting bright enough to see with the unaided eye.

Not all of the gas is blown away — some of it builds up. But if the white dwarf reaches about 1.4 times the mass of the Sun, a chain reaction will blow it apart. And RS Ophiuchi is nearing that limit. So someday, it probably will destroy itself as a supernova — the final outburst of a star that can’t keep quiet.

More about Ophiuchus tomorrow.

Script by Damond Benningfield

 

The gods of ancient Greece had complex and volatile relationships. As an example, there’s the story of Ophiuchus, a constellation that’s low in the eastern sky on June evenings.

In ancient Greece, Ophiuchus represented Asclepius, the god of medicine and the son of the god Apollo.

In one version of this story, Asclepius killed a snake with his staff. But another snake dropped some herbs on the dead one, bringing it back to life. Asclepius then used those herbs to resurrect the son of King Minos.

Business was so good for Asclepius that fewer people were entering the underworld. So Hades, the god of the underworld, complained to Zeus, the king of the gods. Zeus then killed Asclepius with a lightning bolt.

But that didn’t sit well with Apollo. To appease him, Zeus placed Asclepius in the sky. Today, those stars are known as Ophiuchus, the serpent bearer. He’s depicted with a snake wrapped around his waist. And that’s why the symbol for modern medicine is a pair of snakes wrapped around a staff — it’s a representation of the story of Ophiuchus.

Look for the serpent bearer low in the east and southeast as darkness falls. Its stars are faint. Under a dark sky, though, they form a pattern that resembles an old coffee pot, which is on its side in early evening, and upright later on.

The constellation’s brightest star is at the top of the coffee pot — Rasalhague, the “head of the serpent bearer.”

We’ll have more about Ophiuchus tomorrow.

Script by Damond Benningfield