StarDate

If planets had feelings, then Saturn might have an inferiority complex. Although it’s a giant, it ranks second to Jupiter in just about every category. Jupiter is about 10 percent wider than Saturn, and about three times as heavy.

And as seen from Earth, Jupiter is much brighter. Right now, in fact, it’s easy to see that difference for yourself. The planets are close together, and they’re shining at or near their best for the whole year. They’re in the southeast as night falls. Jupiter is far brighter than any other planet or star in the sky for most of the night. Saturn is to its lower left. Although it pales in comparison to Jupiter, it’s quite bright on its own.

The one area where Saturn doesn’t lag behind Jupiter is rings. Jupiter is encircled by several rings. But they’re dark and thin, so they weren’t discovered until late in the last century.

Saturn’s rings, on the other hand, are wide and beautiful. They were visible from the first time anyone looked at the planet through a telescope. They span almost the distance between Earth and the Moon.

As Saturn orbits the Sun, we see the rings at different angles. Right now, they’re tilted at close to their best possible angle. That means they’re especially beautiful when seen through a telescope. And even without a telescope, they contribute a great deal to Saturn’s brightness — one way in which Saturn doesn’t have to feel inferior to any other planet.

More about Saturn tomorrow.

Script by Damond Benningfield

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Perhaps the most famous star in the night sky is Polaris. It’s not especially bright or close by. Instead, it’s famous for its location. It marks the north celestial pole, so it’s also known as the North Star or Pole Star. Today, it’s about two-thirds of a degree from the true celestial pole. But over the next century, it’ll snuggle even closer.

The change is caused by a slow “wobble” in Earth’s rotation. Over a period of 26,000 years, that causes our planet’s axis to draw a big circle on the northern sky. So while Polaris itself will still be around, it won’t keep its position as the North Star.

The axis is moving counterclockwise. So the next moderately bright star it’ll point to is Gamma Cephei. It’s to the right or lower right of Polaris as darkness falls this month. It’ll take over as the North Star in about a thousand years.

After moving past another star of Cepheus, the pole will take aim at Deneb, the “tail” of Cygnus, the swan, around the year 10,000. And 3500 years after that we’ll have the brightest pole star of all, Vega. Neither Deneb nor Vega will be all that close to the true celestial pole, but their brilliance will make up for the gap.

And in about 20,000 years, the pole will come around to Thuban. It marked the pole about 4500 years ago, when it helped architects align the pyramids of Giza. Finally, around the year 28,000, the pole will return to Polaris — closing its great circle on the sky.

Script by Damond Benningfield

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Mars is getting crowded. As of late May, eight probes were operating on the surface or in orbit around the Red Planet. As many as three more missions have been scheduled for launch this month. And as many as five are on the books for the next few years.

The last of this year’s launches is Tianwen-1. The Chinese mission will consist of an orbiter, a lander, and a rover. The orbiter will map the surface and the planet’s magnetic field. It’ll also use radar to peek below the surface.

The lander will touch down in Utopia Planitia — a volcanic plain with a lot of water ice just below the surface. The lander will include a weather station. It’ll also carry the rover, which will look for evidence of microscopic life.

A fourth mission scheduled for this month had to be put off until the next launch window, in 2022. Europe’s Rosalind Franklin rover also will hunt for evidence of life. And it’ll carry a radar that will probe deep below the surface.

NASA’s considering sending a pair of small satellites to Mars in 2022 as well. The Escapade mission would study the atmosphere and how it interacts with the solar wind. And a small Japanese orbiter and a rover also would study the atmosphere.

Two missions are planned for 2024. India will send its second orbiter to Mars, while Japan will send a craft to Mars’s moons. It’ll land on one of them and gather samples for return to Earth — continuing the busy exploration of Mars.

Script by Damond Benningfield

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NASA’s next Mars rover will have a lot on its plate. It will scour an ancient lakebed for signs of life. It’ll carry a small helicopter to help scout its path. It’ll gather about 30 samples for possible return to Earth by a follow-up mission. And if that’s not enough, it’ll also try to extract oxygen from the atmosphere as a test for future human exploration of Mars.

The launch window for the Perseverance rover opens this week. And if all goes well, the craft will arrive at Mars in February. It will touch down in Jezero Crater. Billions of years ago, the crater contained a deep lake. The lake could have persisted for millions of years, making it a good place to look for evidence of past life.

Perseverance will use several instruments to study the crater floor — particularly an ancient river delta, where water flowed into the crater. The instruments can identify organic compounds — the chemistry of life.

The rover also will carry a weather station, 23 cameras, and the helicopter. The tiny chopper is there to demonstrate the technology. But controllers on Earth may use some of its pictures to help plan the rover’s path.

Perseverance also will seal some samples of the Martian dirt, and core samples drilled below the surface, for return to Earth in a few years. Plans call for another rover to land nearby, pick up the samples, and place them on a rocket for the journey to Earth — capping the most ambitious Mars mission to date.

Script by Damond Benningfield

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One of the main reasons for exploring Mars is to hunt for life, past or present — especially microscopic life. But scientists want to make sure that if they find microbes on Mars, they’re actually Martian. So every Mars lander is kept especially clean to ensure it doesn’t carry any bugs from Earth.

Just how clean depends on where the lander is going. Any craft that’s aimed at regions where there might be water — the most likely places to find life — must be especially germ free.

Landers are assembled in cleanrooms, where dust, microbes, and other particles are filtered from the air. Workers wear special gear so they don’t sneeze on the craft or smear them with germy fingerprints.

Landers are sterilized as much as possible. Some parts are baked at high temperatures. Others are wiped with strong germ killers. And some are sealed tightly so any microbes are trapped inside. And the landers are routinely checked to make sure they stay clean.

Finally, the trip through space is likely to kill almost anything that hitches a ride. Even so, it’s possible that some microbes could survive.

Conditions on Mars are almost as harsh as those in space. Radiation, for example, probably has sterilized the top layer of the Martian dirt. So in recent years, some scientists have suggested making the rules less restrictive. For now, though, anyone planning a mission to Mars needs to stock up on cleaning supplies.

We’ll talk about one Mars mission tomorrow.

Script by Damond Benningfield

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The United Arab Emirates has a lofty goal. It wants to have a settlement on Mars in less than a century. And it’s taking its first steps toward that goal. It’s working on a “Mars City” in the desert of Dubai. And it’s planning to launch its first mission to Mars as early as this week. The Hope orbiter would arrive at Mars early next year.

Assuming the coronavirus hasn’t scuttled any of them, it’s one of three missions to Mars scheduled for launch this month. The list includes an American rover and a Chinese orbiter-rover combo. A European mission was put off until the next launch window, in two years — not because of the virus, but because of nagging technical problems.

Hope will study the Martian atmosphere. Many orbiters always see the planet below at the same time of day — day in and day out. Hope, though, will see the full day-night cycle. That will allow it to see changes in the atmosphere that take place at various times of day.

And like several other orbiters, it’ll look at how Mars has lost its atmosphere. The early planet had a much warmer, thicker atmosphere than it does today. Most of that atmosphere has vanished. Some is locked in the Martian rocks and ice caps. But most of it leaked out into space. Hope should provide new evidence of how that happened, and how it’s still happening today — a first step toward the lofty goal of a settlement on Mars.

We’ll have more about the new missions to Mars tomorrow.

Script by Damond Benningfield

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You just can’t block a good storm. On Jupiter, for example, a storm as big as Texas muscled its way into a ring of even bigger storms. Scientists will keep an eye on it to see if it sticks around, and perhaps grows to the same size as the others.

The Juno spacecraft discovered the new storm last year. The craft has been orbiting Jupiter for four years. And last November, it passed just a few thousand miles above the south pole.

During earlier passes, the craft had found a set of six cyclones there, each about as wide as the continental United States. One of them was in the middle, almost directly atop the pole. The other five moved around it, forming a pentagon. And the system seemed to be pretty stable — the configuration stayed the same from pass to pass. By November, though, the new cyclone had joined the outer band, turning the pentagon into a hexagon.

The new storm was less than half the size of the older ones. But wind speeds at its perimeter were the same — about 225 miles per hour.

Jupiter’s south pole isn’t visible from Earth. But Juno will make other passes. The new views will tell us whether the new storm stays the same, grows, or perhaps vanishes — blocked by its bigger cousins.

And Jupiter itself is putting on a great show. It’s brightest for the entire year, shining like a brilliant star. It’s low in the southeast at nightfall, scoots low across the south during the night, and is in the southwest at dawn.

Script by Damond Benningfield

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The planet Jupiter is basically a big ball of gas. It consists mainly of hydrogen and helium, the lightest of all elements.

Yet there’s so much of these elements that Jupiter is the 800-pound gorilla of the solar system. It’s about two and a half times as massive as all the other planets and moons combined.

That gives Jupiter a powerful gravitational pull. And the planet puts that gravity to use — and always has. In the early solar system, Jupiter kicked billions of “leftover” balls of rock and ice into deep space. Some of them orbit the Sun from great distances, but others were ejected from the solar system entirely.

Jupiter still has that kind of influence today. It pushes comets and asteroids into new orbits. And it sometimes rips them apart, or pulls them to their doom by dragging them into the planet itself.

Because of that influence, astronomers must consider Jupiter’s pull when they calculate the orbits of the other planets, moons, and smaller bodies. And engineers have to keep it in mind when they launch spacecraft to other parts of the solar system — the giant influence of a giant planet.

And Jupiter is putting in a giant appearance right now. The planet is at opposition — it’s lining up opposite the Sun. It rises around sunset and is in view all night long. It also shines brightest for the year. It’s low in the southeast at nightfall and looks like a brilliant star.

More about Jupiter tomorrow.

Script by Damond Benningfield

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Tomorrow’s dawn sky is packed with beautiful pairings. They involve the Moon, one bright star, and four brighter planets.

One pair is actually in view all night long. Jupiter and Saturn, the largest planets in the solar system, are low in the southeast as night falls, and in the southwest at dawn.

Jupiter is the giant of them all, and looks it. It’s putting in its best appearance of the year right now, so it shines at its brightest. Only the Moon and the planet Venus are brighter. Saturn, the Sun’s second-largest planet, trails along behind it. It’s only about a week away from its peak, so it, too, is shining brightly. We’ll have more about Jupiter tomorrow.

The second pair is the most obvious: the Moon and the planet Mars. They climb into good view by around 1:30 or 2, and are high in the sky at first light. Mars looks like a bright orange star to the upper right of the Moon. It’s headed toward its best appearance of the year in October, so it’s growing a tiny bit brighter with each passing day.

The final pair rises not long before dawn, and is in the southeast as twilight begins to paint the sky. It consists of Venus, the “morning star,” and Aldebaran, the star that marks the eye of Taurus, the bull. Aldebaran is one of the brighter true stars in the night sky. Yet it’s less than one percent as bright as Venus. But its proximity to the brilliant planet helps it stand out — one of three great pairings in the dawn sky.

Script by Damond Benningfield

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Mars doesn’t rumble any more, but it does rattle.

A robotic lander has measured hundreds of “marsquakes.” Most of them are puny. They’re probably generated in the crust — perhaps as the result of the planet cooling and shrinking.

But some quakes are a little stronger — up to about magnitude four. They probably come from deeper inside the planet — from the boundary between the crust and the mantle. Observations of a few of the quakes have been converted to sound.

Scientists have traced a few of the stronger quakes to a region a thousand miles from the lander. Cerberus Fossae consists of three long, deep “cracks” in the surface. The cracks run parallel to each other. They’re up to about 750 miles long, and a few thousand feet wide. They’re near the equator, to the southeast of a group of three giant volcanoes.

The volcanoes could be responsible for the cracks, which are only a few million years old. Lava flowing below the surface could have left voids that collapsed, for example. As the cracks formed, they could have released vast amounts of pressurized water or lava. The flowing liquid carved channels that aim away from the cracks — more activity around the most geologically active region on Mars.

Look for Mars near the Moon the next couple of mornings. They’re high in the sky at first light. Mars is to the upper left of the Moon tomorrow, and to the upper right on Sunday.

Script by Damond Benningfield

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