StarDate

Anything that’s in Earth orbit faces the constant threat of radiation – energy and charged particles from the Sun and beyond. It can cause instruments to glitch or fail, and even destroy a satellite. And it poses a health risk for astronauts.

The threat is greatest in a zone in the southern hemisphere – the South Atlantic Anomaly. It covers several million square miles above South America and South Atlantic Ocean. It’s a weak spot in Earth’s magnetic field that allows intense radiation to penetrate closer to the surface. And it’s getting bigger.

The magnetic field can deflect many of the charged particles that bombard our planet. That protects orbiting satellites and astronauts. It also protects the surface from power blackouts and other effects.

But the field is offset a bit from the center of the planet. It extends a little farther into space in some regions, but dips closer to the surface in others. And the South Atlantic Anomaly is the biggest dip of all. Spacecraft that are passing through the region often have to switch off some of their instruments to protect them from the harsh radiation.

A recent study found that the anomaly has gotten bigger over the past decade – by about half the area of continental Europe. So the space above that part of Earth is getting nastier – a bigger “danger zone” in the southern hemisphere.

We’ll have more about radiation hazards tomorrow.

Script by Damond Benningfield

To the eye alone, the Pleiades cluster looks like a small dipper of about seven stars – a few more if you have nice, dark skies. But when Galileo Galilei looked at it with his first small telescope, he saw a few dozen stars. It was one of the first indications that there’s far more to the universe than meets the eye.

You can share Galileo’s view with a basic pair of binoculars – no telescope required. They’re especially helpful tonight because of the Moon. It passes through the outskirts of the cluster, so it points the way. But the moonlight makes it tougher to see the stars.

The Pleiades is a family of perhaps a couple of thousand stars. The stars were all born together, from the same cloud of gas and dust. That makes the cluster a good laboratory. Since the stars all started with the same mix of elements, any differences among them are the result of their evolution – changes within the stars themselves. That helps astronomers understand how all stars change over the eons.

The cluster probably is a little more than a hundred million years old. That means it’s completed only about half an orbit around the center of the galaxy. During that time, it’s lost many of its original stars. And before it can complete one full orbit from its current location, it’s likely to evaporate – pulled apart by the gravitational tug of the rest of the galaxy.

Tomorrow: a growing “danger zone.”

Script by Damond Benningfield

Stars aren’t always nice to their offspring – especially at the end. As a star dies, it expands. It can get big enough to engulf some of its planets. The Sun, for example, is likely to swallow Mercury and Venus, and might get Earth as well.

A star in Cygnus might have engulfed one of its planets fairly recently. Two others might be doomed as well.

Kepler-56 isa red giant – a dying star that’s much bigger than the Sun. It has three known giant planets. Two of them are quite close in, so they may not survive the star’s final act.

Kepler-56 is rotating much faster than most red giants. And vibrations at the surface reveal that its core and its outer layers are spinning at different rates and angles. There are several possible reasons for this odd behavior. One is the gravitational influence of the close-in planets. Another is that the star might have swallowed a planet early on.

A recent study suggested something else: The star might have swallowed a planet fairly recently. The planet would have been about as massive as Jupiter, the giant of our own solar system. As it plunged in, its orbital momentum spun the star up. So Kepler-56 isn’t being kind to its offspring as its own life comes to an end.

Kepler-56 is in the east-northeast at dawn. It’s half way between Deneb, Cygnus’s brightest star, and even brighter Vega. But Kepler-56 is too faint to see without a telescope.

Script by Damond Benningfield

Things sometimes flash in the night sky. That includes some weird and wonderful astronomical objects. Some of them shine for a few minutes or even seconds, then vanish. So it can be tough to understand just what caused them.

Thousands of these “transients” showed up in a decade-long look at the night sky. And a recent study found a statistical link between some of those transients and both nuclear weapons tests and reports of UFOs.

The study analyzed thousands of nights of observations by the Palomar Sky Survey. From 1949 to 1958, astronomers repeatedly photographed the night sky on glass plates, looking to compile the best map of the heavens to date. Many of the plates revealed transients that were star-like pinpoints of light.

They appeared out of nowhere, then disappeared just as quickly.

The study found that, on average, the number of transients was greater on nights just after above-ground nuclear explosions. And there were more reports of UFOs on nights with more transients.

There are many possible explanations. There could be problems with the original plates, for example. The nukes could’ve created some previously unknown effects in the atmosphere. The study also says the flashes could have been metallic objects far above our planet – perhaps even visitors from other worlds.

But many scientists say we need a much more thorough look at the pictures before we’ll know what caused these flashes in the night sky.

Script by Damond Benningfield

Long-term missions to the Moon and Mars will need a good understanding of the machines, the environment – and the people. Friction among crew members could make a mission much less productive – or even endanger lives.

To minimize the risk, scientists are trying to understand how people get along during long periods of isolation. They’ve conducted test runs in laboratories. They’ve set up habitats on volcanoes and remote islands. They’ve studied research bases in Antarctica. And they’ve sent volunteers into the oceans.

As with space travel, an undersea habitat is isolated and cramped, and the environment can be deadly. So it’s important for the crew to get along.

NASA has conducted quite a few underwater expeditions. For many of them, astronauts spent a few days or weeks in a habitat off the coast of Florida. They conducted experiments both inside and outside the lab. They tested equipment and techniques that might be used in space. And scientists checked out how well they worked as a team.

Recently, the European Space Agency sent 25 volunteers on a two-month trip aboard a submarine. Scientists used questionnaires to check on the volunteers. They also took samples of hair and saliva. The results helped track stress markers, changes in the immune system, and other reactions – better understanding the human factor in long-term missions to other worlds.

Script by Damond Benningfield