StarDate

The south pole is high, dry, and cold. It sits about two miles high, and it gets only two or three inches of snow per year. The humidity is near zero, and the average temperature is more than 50 below. That makes it a tough place to live — but a great spot for studying the universe. Telescopes work best under high, dry skies, where there’s little air or water vapor to interfere with the view.

In fact, two major observatories operate at the south pole all year long. One of them looks up into the sky, while the other looks down through the solid Earth.

The South Pole Telescope watches the universe at radio wavelengths. Among other projects, it’s looking for evidence of dark energy. Dark energy appears to account for most of the “stuff” that makes up the universe. So far, though, scientists can’t explain it.

An observatory known as IceCube looks for evidence of neutrinos — particles that almost never interact with other forms of matter. They’re of interest because they’re produced by exploding stars and other powerful events.

IceCube consists of thousands of light detectors buried a mile deep in the ice. When a neutrino strikes a particle of other matter, it produces a flash of light. Neutrinos pass all the way through Earth, so IceCube uses the planet to screen out other signals.

Several scientists and engineers spend the long, dark winter at the pole to help keep these special “eyes” focused on the universe.
 

Script by Damond Benningfield

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The Space Age has produced some remarkable images: astronauts walking on the Moon, the rings of Saturn, the surface of Pluto. But few are more impressive than the Pillars of Creation. Snapped in 1995 by Hubble Space Telescope, the picture shows three towers of dark gas against a colorful background. Embedded inside the towers are the glowing “eggs” of newly forming stars.

The pillars are part of the Eagle Nebula — a cloud of gas and dust that’s more than 50 light-years wide. It’s in the south after night falls, above the “teapot” outlined by the stars of Sagittarius. It’s too faint to see with the eye alone.

The nebula is a stellar nursery. Over the last few million years, it’s given birth to hundreds of stars.

Its most massive stars are much bigger, heavier, and hotter than the Sun. They pump out lots of ultraviolet energy. That causes the surrounding gas to glow like a neon bulb, making the nebula look red. Its outline resembles an eagle with wide-spread wings.

The Pillars of Creation account for only a small part of the nebula. The tall pillars contain pockets of dense, cold gas and dust — known as eggs — that are collapsing to form even more stars.

But the hot young stars are blasting away the surrounding gas and dust. That shuts down star formation. In another hundred thousand years or so, all of the raw materials for making new stars may be gone — toppling the remarkable Pillars of Creation.
 

Script by Damond Benningfield

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A star cluster in Serpens, the serpent, blazes with the fires of hundreds of young stars. And it’s not that far away — just 1400 light-years. That should make it an easy target for telescopes. Yet until a few years ago, no one knew it even existed. That’s because the stars are still embedded in their stellar womb — a vast cloud of gas and dust that’s cold and dark. It took an infrared telescope in space to peer through the cloud and reveal the stars.

The cluster is part of a giant complex of young and developing stars that spans hundreds of light-years. Astronomers had already discovered a large cluster near the center of this complex. And in 2008, they found the new cluster in the southern part of the cloud.

Astronomers have seen several hundred “young stellar objects” in Serpens South. Some are stars, but many are proto-stars — collapsing balls of gas that aren’t yet shining as true stars.

The cluster is embedded in long, dark filaments of gas and dust. The filaments appear to be collapsing toward the stars. And gas from the larger cloud is falling onto the filaments. That’s funneling more raw materials toward the cluster, so it’s likely to give birth to more stars in the future.

Although the cluster is too faint to see, its part of the serpent is in the southern sky at nightfall, above the “teapot” outlined by the stars of Sagittarius.

We’ll talk about another stellar nursery in the serpent tomorrow.
 

Script by Damond Benningfield

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Some scientific debates take a long time to resolve. Consider ALH84001. 25 years ago today, NASA announced that the meteorite from Mars contained evidence of ancient microscopic life. The news even brought a comment from President Bill Clinton.

CLINTON: Today, rock 84001 speaks to us across all those billions of years and millions of miles. It speaks of the possibility of life. If this discovery is confirmed, it will surely be one of the most stunning insights into our universe that science has ever uncovered.

Yet there was no confirmation from other scientists. Instead, there was near-universal disagreement.

NASA scientists had spent years examining the meteorite. They found shapes that looked like the fossils of microscopic organisms. They found minerals that formed four billion years ago, when Mars was warm and wet. They found organic compounds — the building blocks of life. And they found tiny magnetic crystals like those produced by life on Earth.

But other scientists disagreed with the conclusion. Their work showed that the possible fossils were too small, the chemistry wasn’t right, and the crystals could have formed when a shockwave rippled through the rock.

Yet the scientists who did the original work still say the rock shows evidence of life. A few other studies say that life is unlikely, but it can’t be ruled out. So the debate about life in this meteorite from Mars continues.
 

Script by Damond Benningfield

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A trio of rovers is looking for evidence of life on the Red Planet — past or present. One of them is even gathering samples that might one day be returned to Earth by a follow-up mission. That would give scientists a chance to study the samples with the most advanced technologies on Earth.

In the 1990s, scientists studied a Mars rock with the most advanced technologies of the time. And 25 years ago this week, they reported finding evidence of life.

The rock was a Mars meteorite. It formed more than four billion years ago, when lava on Mars cooled and solidified. It was blasted into space about 16 million years ago when an asteroid slammed into Mars. The rock fell to Earth in Antarctica 13 thousand years ago. It was discovered in the Allan Hills in 1984, so it was named ALH 84001.

Scientists discovered that it came from Mars by measuring tiny air bubbles in the rock. Gases in the bubbles match those in the Martian atmosphere.

NASA scientists spent years analyzing tiny fragments of the rock. A combination of several findings hinted that the rock held evidence of ancient microscopic life — a stunning discovery.

Soon, though, other scientists looked at pieces of ALH84001 as well. Most of them concluded that the evidence of life had been produced by chemical or geological processes — not by Martian “bugs.” Yet the debate about the meteorite continues; more about that tomorrow.
 

Script by Damond Benningfield

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Titan, the largest moon of Saturn, is a deep freeze. Surface temperatures are close to 300 degrees below zero Fahrenheit. But Titan would be even colder without one of the components of its atmosphere: methane. The gas traps heat from the Sun, making Titan dozens of degrees warmer.

Although it makes up only a small fraction of the dense atmosphere, methane plays a critical role in shaping Titan’s surface. That’s because it acts as water does here on Earth: It forms clouds, falls as rain, and fills lakes.

Scientists aren’t sure where the methane comes from, though. Methane floats to the top of the atmosphere, where it’s destroyed by sunlight. The total supply in the atmosphere today wouldn’t last more than 10 million years. So more methane must somehow be entering the atmosphere.

There are several possible ways that could happen.

There may be deposits of methane-rich ice far below the surface. Some of the ice could make its way to the surface—perhaps through volcanoes—where it would vaporize and climb into the sky. Scientists are using observations by telescopes in space and on the ground to try to pinpoint the source of this key ingredient in Titan’s frigid atmosphere.

Bright golden Saturn is at its best for the entire year this week. It’s low in the southeast at nightfall, and remains in view all night, to the right of brighter Jupiter. Through a telescope, Titan looks like a tiny star close to the giant planet.
 

Script by Damond Benningfield

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An “astonishing” star should be at its best this month. The star puffs in and out like a beating heart, getting brighter and fainter with each beat. It’s in the “contraction” phase now, so it could reach its brightest around the middle of the month.

The star was noted 425 years ago today by David Fabricius. When he looked at it a couple of weeks later, it was noticeably brighter. But by a couple of months after that, the star had vanished.

Later, another astronomer figured out that the star brightens and fades every 11 months. And a third astronomer named it Mira — a Latin word meaning “astonishing” or “wonderful.”

Mira is at the end of its life. It’s a little heavier than the Sun, and much bigger. Its exact size varies by about 20 percent — from more than 300 times the Sun’s diameter to about four hundred.

That’s because the star is making a transition in the way it produces energy. That process is unstable, so the star has gotten a lot bigger. It’s also made the outer layers unstable, causing them to pulse in and out. When Mira is smallest, it’s also hottest, so it shines brightest.

And the star is headed toward that point in its cycle. That should make it an easy target — something we can’t always say about this “astonishing” star.

Mira is in Cetus, the sea monster. It climbs into good view by about 2 a.m., and is high in the sky at first light. It’ll rise earlier over the coming weeks, and stand due south at dawn.
 

Script by Damond Benningfield

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75 years ago today, lunchtime at the Gage Ranch, near Marathon, Texas, was interrupted by a surprising visitor: a space rock. It slammed into a swimming hole with a bang, breaking apart and splashing mud and water up to a hundred feet away. Two dozen people were close enough to see or hear the impact, and one even saw the rock falling through the sky.

It was named the Peña Blanca Spring meteorite. It fractured when it hit, but workers gathered about 155 pounds of it.

The original rock may have been a fragment of an asteroid that passes close to Earth. Sometimes, though, an entire asteroid hits Earth. If the asteroid is big enough, that can be catastrophic. So astronomers are searching for all the asteroids that could pose a threat.

With enough warning time, we might be able to deflect an asteroid. If the warning time is short, though, there might be just one solution: nuke it.

If a bomb exploded near the asteroid, it would vaporize material at the surface. That would create a “jet” of hot gas that could nudge the asteroid. And an explosion inside the asteroid might blow it apart and push the pieces safely away.

To make the bomb work most efficiently, planners would need to know many details about the target asteroid. So astronomers are studying asteroids to learn more about them. Scientists also are studying bits of meteorites in the lab — providing key details to help protect us from falling space rocks.
 

Script by Damond Benningfield

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Saturn is at its best for the entire year right now. The second-largest planet in the solar system rises around sunset and is in view all night. And it shines at its most brilliant. It looks like a bright golden star. It’s low in the southeast as night falls, arcs across the south during the night, and is in the southwest at first light. The brighter planet Jupiter follows well behind it — getting ready to stage its best display in a few weeks.

Saturn is putting on such a good show because it’s at opposition. That means it lines up opposite the Sun in our sky. It can do so because it’s a superior planet. That’s not a judgement of its character or beauty — although its rings do make it a beautiful sight. Instead, it’s an indication of Saturn’s place in the solar system.

Superior planets are farther from the Sun than Earth is — almost 800 million miles farther, in the case of Saturn. So as Saturn and Earth orbit the Sun, we see Saturn at different angles relative to the Sun. It can pass behind the Sun, huddle close to it, or appear as far from the Sun as an object can get — 180 degrees away — all the way across the sky.

It takes about 12 and a half months for Saturn to move from one opposition to the next. So next year’s opposition will be in the middle of August, not at the beginning — when the “superior” planet Saturn will once again appear at its best.

We’ll have more about Saturn later in the week.
 

Script by Damond Benningfield

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One year ago today, the Arecibo radio telescope in Puerto Rico took a close look at a passing asteroid. And it reported some good news: the asteroid isn’t a threat to hit Earth anytime soon.

Asteroid 2020 NK1 had been discovered just weeks before. Early observations indicated it had a small chance of hitting Earth in 2043.

Astronomers have discovered about 25,000 asteroids that routinely pass close to Earth. Some of them come close enough that they’re considered a hazard — they could someday slam into Earth. About 160 of those are at least a kilometer in diameter — big enough to cause destruction across hundreds of thousands of square miles.

Arecibo astronomers had planned to take a look at NK1 on July 30th. But a tropical storm was passing over the island, so they had to wait until the next day. They beamed radio waves at the asteroid, which was five million miles away. Reflected radio waves were captured by the thousand-foot telescope. They revealed that NK1 is about a kilometer long — making it especially deadly if it hit. But Arecibo tracked the asteroid long enough, and with enough accuracy, to nail down its orbit. That showed that NK1 will miss us by a couple of million miles.

Arecibo tracked many other asteroids over the years. But cables that supported the telescope’s receivers broke last fall, forcing a shutdown. And the whole thing collapsed in December — demolishing an astronomical watchdog.
 

Script by Damond Benningfield

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