StarDate

Mars has many ways to “get” a visiting probe. It’s cold, it’s dry, and its air is thin, for example. But the biggest threat is dust storms. In fact, a giant storm may have doomed the first object to hit the Martian surface.

Mars 2 was dispatched by the Soviet Union in May of 1971. It consisted of an orbiter and a lander. They arrived at Mars 50 years ago today.

But a massive dust storm was under way. It covered the entire planet. Only the tops of a few tall mountains peeked above it.

An American spacecraft, Mariner 9, had entered orbit around Mars a couple of weeks earlier. It was designed to be flexible. So when scientists saw that Mars was hidden from view, they waited a couple of months to begin its work.

Mars 2 and a sister mission, Mars 3, didn’t have that flexibility. They were programmed to dispatch their landers shortly before they arrived at Mars, and those instructions couldn’t be changed. So the Mars 2 lander dropped into that massive dust storm on November 27th, 1971.

And things didn’t go well. The landing system malfunctioned, and the parachute didn’t open — perhaps influenced by the dust storm. So the Mars 2 lander crashed — the first human artifact on the surface of Mars.

The orbiter continued its mission, but it didn’t see much through the dust. It did obtain important readings on the Martian atmosphere and magnetic and gravitational fields — adding to our then-meager knowledge of the Red Planet.
 

Script by Damond Benningfield

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The constellation named for the giraffe is tall, as you might expect. But it isn’t bright. None of its stars is brighter than fourth magnitude. That means you need dark skies to see them — away from the glare of city lights.

Camelopardalis wraps around Polaris, the north star. Its main outline is in the north-northeast at nightfall. It stands high above Polaris around midnight, and whirls to the north-northwest at first light.

The constellation was created by Petrus Plancius, a Dutch astronomer and priest. He drew it on a celestial globe in the early 17th century. He linked up some stars in a dark region of the sky, where no one had bothered to create a constellation before.

The fact that we see some of the giraffe’s brighter stars at all is a testament to the stars themselves. The brightest star, Beta Camelopardalis, is more than 850 light-years away. The star is a yellow supergiant. It’s about the same temperature as the Sun, but much bigger and heavier, and thousands of times brighter.

The third-brightest star, known as Alpha, is even more impressive. It’s a blue supergiant. It’s not only bigger and brighter than the Sun, it’s thousands of degrees hotter as well. And it’s visible from a distance of 6,000light-years — one of the most-distant stars that’s visible to the unaided eye.

So if you have a clear, dark sky, look toward the north for Camelopardalis — a big, faint constellation with some impressive stars.
 

Script by Damond Benningfield

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Regulus, the star at the heart of the lion, has a small, faint companion. Astronomers have known about it for a while, but they’ve never seen it. In fact, they’ve had a hard time figuring out its details.

That’s because the two stars are quite close together, and because Regulus itself is far brighter than the companion. So trying to see the other star is like trying to pick out a flashlight right next to a searchlight.

Astronomers discovered the companion by breaking the light from Regulus into its individual wavelengths or colors. Patterns in that rainbow of colors reveal details about Regulus. Detailed observations reveal a second pattern mingling with the first — the imprint of the companion.

A study last year got the best look yet at that second imprint, allowing astronomers to nail down some of the companion’s details. It’s about a third the mass of the Sun, compared to almost four times the Sun’s mass for Regulus. Its surface is thousands of degrees hotter than the Sun’s. And it’s about six percent the Sun’s diameter.

The star is becoming a white dwarf — the final stage of life for a Sun-like star. Eventually, the star will get even smaller, and a bit cooler. That’ll make it even harder to see through the glare of brilliant Regulus.

Look for Regulus near the Moon the next couple of nights. It rises below the Moon late tonight, and stands to the lower left of the Moon at first light. It’ll be even closer to the Moon tomorrow night.
 

Script by Damond Benningfield

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The asteroid that wiped out the dinosaurs was like a cosmic reset button. It killed off most of the life on Earth, which made it possible for modern life to take control.

The asteroid was a few miles in diameter. It hit off the coast of Mexico 66 million years ago. It caused a massive tsunami, plus a firestorm that blacked out the Sun and created acid rains across the entire planet. About three-quarters of all the plant and animal species died off — in both land and sea.

On land, dinosaurs and other big animals died off quickly. That let small mammals begin to dominate the landscape.

A couple of recent studies have found other changes that followed the mass extinction. One study says it destroyed almost half the vegetation in the Amazon rainforest. It took millions of years to redevelop. Trees with thin canopies, which allow dense vegetation to grow at the surface, were replaced by flowering trees with much thicker canopies. That transformed the rainforest’s appearance.

A study in September said that snakes profited from the changes as well. Many of them were able to remain underground, without food, for up to a year at a time. As conditions improved, they returned to the surface. With most life eradicated, there was less competition for limited food supplies. So snakes multiplied, evolved, and spread out across the planet — beneficiaries of a global catastrophe.

Tomorrow: Looking into the details of a tiny companion.
 

Script by Damond Benningfield

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A NASA spacecraft whose launch window opens tomorrow is being sent on a suicide mission. It will destroy itself by slamming into a small asteroid. By doing so, it may help save lives by keeping future asteroids from slamming into Earth.

DART — the Double Asteroid Redirection Test — will arrive at a binary asteroid in about 10 months. The larger member of the system, Didymos, is a half-mile in diameter. Its companion, Dimorphos, is only about a tenth of a mile across.

DART will hit Dimorphos head on, at a speed of about 15,000 miles per hour. The impact should change the smaller space rock’s orbit. Astronomers will use several telescopes to track the impact and its aftermath to see how much the orbit changes.

The goal is to help determine if we could deflect an asteroid on a collision course with Earth. An asteroid the size of Dimorphos could cause a lot of damage. And a larger asteroid could cause a global catastrophe. If we know about the impact far enough in advance, though, we might be able to push the asteroid onto a safe path.

One way is by slamming stuff into it, and this is the first test to see how well that might work. DART is expected to shorten the length of Dimorphos’s orbit by several minutes. Astronomers will precisely measure the orbit to see if that’s the case — telling us if we’re on the right track in the effort to save Earth from killer asteroids.

Tomorrow: Hitting a cosmic reset button.
 

Script by Damond Benningfield

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A new project says it’s time for ET to come in from the cold. It plans to look for evidence of alien civilizations not in other star systems, but right here in our own.

Astronomers have been searching for extraterrestrial intelligence for decades. They’ve used radio telescopes to hunt for signals from other star systems. More recently, they’ve also been hunting for high-powered lasers. So far, they haven’t found a thing.

Project Galileo will look for evidence that other civilizations are poking around the solar system. The project is headed by Avi Loeb, a scientist at Harvard.

The project was motivated by several developments. In 2017, the first known interstellar object, ‘Oumuamua, passed through the solar system. It moved in odd ways. It might have been a comet. But Loeb suggested it could have been a probe from another civilization.

And this June, the military released a report on UFOs seen in the last decade by military pilots. The report said many of the sightings couldn’t be explained — but it didn’t say they were extraterrestrial.

The plan calls for Galileo to scan the skies for evidence of UFOs with a network of small telescopes. It’ll also look for more interstellar visitors like ‘Oumuamua. It’ll even scan for alien satellites in orbit. The project will use AI to sift through all the data. And it’ll make its findings public — letting the rest of us know if it sees any evidence of alien technology close to home.
 

Script by Damond Benningfield

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If you draw Earth’s orbit around the Sun, it looks like a circle, with the Sun right in the middle. But that picture is a bit misleading. Earth and the Sun actually orbit a common point — the center of mass for the system. Since the Sun is about 330,000 times heavier than Earth, that center is deep within the Sun itself. So the conventional picture of Earth’s orbit is just fine for everyday uses.

For objects of similar masses, though, it’s a different story. Consider Capella, the brightest star of Auriga the charioteer. It consists of two pairs of stars, although only one pair is bright enough to see without a good telescope.

The stars in the bright pair are almost equal — about two-and-a-half times the mass of the Sun — so the center of mass is half-way between them. So when you trace out their orbits, it looks like a pair of toy trains going around and around on the same circular track.

Because the stars are the same mass, they also have the same life history. They’re both puffing up to become giants. And they face the same fate — both will blow off their outer layers and end their lives as the faint cinders known as white dwarfs. That won’t happen for tens of millions of years, though, so Capella will continue to shine brightly for a long time to come.

Right now, look for it low in the northeast at nightfall, and high in the northwest at first light. It’s one of the brighter stars in the night sky, so you can’t miss it.
 

Script by Damond Benningfield

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The gibbous Moon lines up between two bright stars tonight, with an even brighter star not far away. The Moon will move toward the faintest of the three stars during the night.

As night falls, Aldebaran will stand to the right of the Moon. El Nath — the “butting one” — will be closer to the left of the Moon. And brilliant Capella will be well to the upper left of the Moon.

The closer stars both belong to the classic outline of Taurus, the bull. Aldebaran is the bull’s orange eye, while El Nath marks the tip of one of its horns.

But El Nath also belongs to the outline of Auriga the charioteer. Officially, it’s a member of that constellation, and not Taurus. In fact, it’s the second-brightest star in the whole constellation, after Capella.

When the constellations were first drawn, thousands of years ago, it really didn’t make much difference if one star had a dual identity. But about a century ago, astronomers created precise boundaries for each constellation. So while a star could remain part of two star pictures — the outlines of two different figures in the sky — it was given just one official residence. In the case of El Nath, it’s Auriga.

Although El Nath is fainter than the other two stars, the Moon will scoot closer to it during the night. They’ll be pretty close together at first light — making the star with two constellations even easier to pick out.

We’ll talk about Capella tomorrow.
 

Script by Damond Benningfield

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Astronomers spent decades hunting for planets around the star Aldebaran, the bright orange “eye” of the bull. And they found one. But their work also revealed details about Aldebaran itself.

The astronomers looked at Aldebaran hundreds of times with telescopes at McDonald Observatory and elsewhere. They measured a small shift in its light caused by the gravitational tug of the planet.

A few years ago, other astronomers combined those observations with some made by a space telescope. They found changes on the surface of Aldebaran caused by sound waves rippling through its interior. How the waves move through the star reveals important details about how the star is put together, just as sound waves moving through Earth reveal details about how it’s put together.

Those details helped revise much of our knowledge of Aldebaran. They showed that it’s only about 16 percent heavier than the Sun — a good bit less massive than earlier estimates. They also showed that it’s about six-and-a-half billion years old — a couple of billion years older than the Sun.

So the hunt for planets around other stars is also helping us learn about the stars themselves.

Aldebaran is especially easy to find the next couple of nights because it’s close to the Moon. It rises a little below the Moon early this evening, and about the same distance to the right of the Moon tomorrow night. The two bodies will stay close together throughout both nights.
 

Script by Damond Benningfield

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The second lunar eclipse of the year takes place late tonight. Although it’s not a total eclipse, it’ll be hard to tell the difference. The whole thing will be visible from all of the United States, except for a sliver of the East Coast, where the Moon will set shortly before the eclipse ends.

A lunar eclipse occurs when the full Moon passes through the dark central portion of Earth’s long shadow, known as the umbra. The Moon’s orbit is tilted a bit, so most months the Moon passes a little above or below the shadow. An eclipse occurs only when the geometry is just right.

On average, that happens two or three times per year. Some eclipses are total, so the Moon is completely immersed in the shadow. Others are less complete, so they’re known as partial eclipses. Any spot on Earth will see an average of about one lunar eclipse a year, and all or part of a total eclipse about once every other year.

Tonight’s eclipse gets started at 1:18 a.m. Central Time, when the umbra first touches the lunar disk. At the eclipse’s peak, less than two hours later, the umbra will cover 97 percent of the Moon’s diameter. The remaining sliver will be in Earth’s faint outer shadow, so the entire lunar disk will be at least partially shaded. It’ll look orange or red — the result of sunlight filtering through Earth’s atmosphere. The partial eclipse ends at 4:47, when the Moon leaves the umbra behind — and returns to the sunlight.
 

Script by Damond Benningfield

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