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• More Geminid Meteors

  People collect all kinds of things, from baseball cards to Persian rugs. Over the past 40 years, some NASA aircraft have collected dust – grains of dust from beyond Earth. Many of the collection efforts have taken place during meteor showers. That’s included the Geminid shower, which is at its peak tonight. A meteor shower takes place when Earth flies through a trail of particles that were shed by a comet or asteroid. Many of the particles burn up in the upper atmosphere, creating the streaks of light known as meteors. But many more grains are too small to burn up. They float down through the atmosphere. Some of them stop at a height of about 10 miles. And that’s where the research aircraft head. Once there, they open up small boxes that catch whatever is drifting along – pollen grains, parts of bugs, bits of volcanic ash, and even exhaust from rocket engines. Analysis reveals whether the captured particles are from Earth or from outside. The cosmic particles can then be tied to the meteor shower that was under way. And that can tell scientists about the shower’s parent body – a sample-return mission that never leaves Earth. The Geminids are in good view tonight. The meteors are visible from mid-evening on. At its best, the shower might produce a hundred or so meteors per hour. And you don’t need to look in a particular direction to see them – just look up and wait for the fireworks. Script by Damond Benningfield

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• Geminid Meteors

  A couple of thousand years ago, a large asteroid or comet might have been blasted apart. And we’re still seeing the fireworks from its destruction – as the Geminid meteor shower, which will reach its peak tomorrow night. Most meteor showers flare to life when Earth passes through the orbital path of a comet. The comet sheds bits of rock and dirt, which spread out along its orbit. As Earth flies through this trail of debris, the solid grains ram into the atmosphere, forming the glowing streaks known as meteors. But the Geminids are a bit odd. For one thing, their parent body – 3200 Phaethon – appears to be an asteroid or a “dead” comet, not an active comet. For another, the meteor stream contains way more material than we’d expect to see from a body the size of Phaethon. A couple of years ago, scientists came up with a possible explanation. They used observations by a Sun-orbiting spacecraft that passed through the meteor stream. They then used computer models to calculate a possible cause for the stream. They concluded that a larger body could have been destroyed. That produced Phaethon and a couple of other large remnants. But it also produced a giant cloud of dust and pebbles. So while some of the material that makes up the Geminids comes from Phaethon, a lot of it also comes from that cloud – shrapnel that makes fireworks in Earth’s night sky. More about the Geminids tomorrow. Script by Damond Benningfield

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• Stabilizing Influence

  The Sun isn’t easy to influence. It’s more than a thousand times the mass of Jupiter, the solar system’s largest planet, and more than 330,000 times the mass of Earth. Even so, a recent study says the planets might influence our star’s magnetic cycle – perhaps making conditions more comfortable for life. The Sun goes through many cycles of magnetic activity. The best known lasts an average of 11 years. At the cycle’s peak, the Sun is much more active than average. It pelts Earth and the other planets with higher levels of radiation and charged particles. That can wreak havoc with everything from satellites to blood pressure. Another cycle lasts an average of less than two years. It produces “mini” peaks and valleys in the 11-year cycle. And it lines up well with the longer cycle. In the recent study, researchers from Germany compared these cycles to the orbits of the planets. They found that the peaks and valleys of the shorter cycle correspond to some planetary alignments. One was a lineup of Earth, Jupiter, and Venus. The other was an alignment of Jupiter and Saturn. The researchers said the planets may help control the solar cycles. The planets might even tamp down the Sun’s activity, which is weaker than that of many Sun-like stars. Less activity means that Earth gets bombarded by less of the nasty stuff – making our planet a much more comfortable home for life. Tomorrow: cosmic shrapnel. Script by Damond Benningfield

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• High Blood Pressure

  Storms on the Sun can cause all kinds of problems. They can knock out satellites and black out power grids. They can interfere with GPS and disrupt some radio broadcasts. They can even have an impact on human health. Solar storms happen when the Sun’s magnetic field gets tangled up. Lines of magnetic force can snap, then reconnect. That produces outbursts of radiation and charged particles. When the particles hit Earth, they’re funneled toward the surface by our planet’s own magnetic field. And that’s what causes the problems. Among the health concerns, particles and radiation can penetrate deeper into the atmosphere around the magnetic poles. That zaps anyone who’s flying at high altitudes in those regions. It’s not a fatal dose, but it’s enough to cause concerns. So airlines divert flights to avoid exposing passengers and crew. There’s also evidence that these bouts of “space weather” can boost people’s blood pressure. In one study, researchers in China looked at half a million blood pressure readings taken over six years. And they found a definite jump around the time of solar storms – especially among women and those with hypertension. An American team found similar results among older men. There’s no consensus about how space weather might cause blood pressure to spike. For now, all we know is that stormy skies on the Sun can cause lots of problems for the people on Earth. Script by Damond Benningfield

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• Moon and Regulus

  The Moon and the heart of the lion just miss each other tonight – at least as seen from the United States. As they climb into good view, after midnight, the Moon and the star Regulus will be separated by just a skosh. The farther north and east your location, the closer together they’ll appear. From some spots, they’ll be almost touching. And from much of Canada across to northern Norway they will touch – the Moon will occult the star. It’ll pass directly in front of Regulus, blocking it from view. The Moon can occult Regulus because the star lies almost atop the ecliptic – the Sun’s path across the sky. The Moon stays close to the ecliptic as well, but it does move a few degrees to either side. As a result, occultations of Regulus come in groups. This one is part of a cycle of that began earlier this year and will continue through the end of next year. Each occultation is visible from a different part of Earth. In part, that’s because each one lasts only a few minutes to a few hours, so the Moon and Regulus are below the horizon as seen from much of the world. Also, the Moon is so close to us that there’s a big difference in the viewing angle across the globe – up to two degrees – four times the width of the Moon itself. From any specific location, sometimes the angle is just right, but more often it’s a little off – providing a beautiful close encounter between the Moon and the heart of the lion. Script by Damond Benningfield

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