StarDate

The success of NASA’s Artemis I mission last year means the agency is getting closer to sending astronauts back to the Moon. A crew could land on the Moon within a few years, spending up to a week on the surface. And within a decade or two, astronauts could be spending weeks or months there.

But it won’t be easy. There’s no air, and temperatures range from a couple of hundred degrees above zero to a couple of hundred below, so habitats and spacesuits will need to be airtight and well insulated. And the lunar day lasts about a month, which could mess with a person’s normal day-night rhythm.

There are many other hazards as well. With no protective atmosphere, the Moon is constantly bombarded by small space rocks, which could puncture spacesuits or living quarters. And with no magnetic field, it’s bombarded by radiation from the Sun and beyond. In fact, big solar storms could be deadly.

There are ways to protect the astronauts. Habitats could be buried under dust and rock, screening out most hazards. And spacesuits could be made of materials that are stronger than earlier suits. Scientists and engineers are working to make all of that happen — as astronauts prepare to return to the Moon.

The Moon climbs into good view by 9 p.m. or so. It’s followed a bit later by Spica, the brightest star of Virgo. The Moon will inch closer to the star during the night, and they’ll be just a couple of degrees apart at dawn.
 

Script by Damond Benningfield

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Mars isn’t quite dead yet. A volcanic region on the planet appears to have stayed active for the past 500 million years. And it’s still producing tremors in the Martian surface.

Tharsis is the largest volcanic region on Mars. It consists of several giant volcanoes, including some of the largest in the entire solar system. It also includes hundreds of smaller volcanoes, plus many related features.

The volcanoes began building about four billion years ago. And many of them have kept building until fairly recently. We don’t see any eruptions today. But there’s evidence that some of them may have erupted within the past hundred thousand years — the blink of an eye on the planetary time scale.

And a recent study found that the activity may not be over yet — below the surface. Images reveal big boulder slides on the flanks of some of the volcanoes and other features — perhaps triggered by volcanic activity. And the InSight lander, which listened for marsquakes, heard activity in the region as well — including one of the most powerful quakes during its entire mission.

A research team says that probably means there are still pockets of molten rock below some Tharsis volcanoes — so at least part of Mars isn’t dead yet.

Look for Mars high in the southwest as darkness falls. It looks like a bright orange star. A true star stands close above it: El Nath, “the butting one” — the tip of the horn of Taurus, the bull.
 

Script by Damond Benningfield

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Comets are as fickle as the weather — and just as hard to predict. A prime example is Comet Kohoutek. It was discovered in a picture shot 50 years ago today. And early predictions said it could become the “Comet of the Century.” Instead, it was a public relations bust. It became barely visible to the unaided eye, but most people never saw it.

Comets are balls of ice mixed with dust and rock. When they pass close to the Sun, they release gas and dust, forming a long, glowing tail.

The comet was discovered by Czech astronomer Lubos Kohoutek. It was farther away than any other comet yet seen, and it would pass quite close to the Sun in December 1973.

Based on its distance and brightness, astronomers forecast that it could become quite bright. But they warned that comets are hard to predict.

Even so, they showed a lot of enthusiasm, which caught on with the public and media. Astronomers observed the comet with telescopes on the ground, plus a Sun-watching space telescope and a craft en route to Mercury. NASA even delayed the launch of the final Skylab crew so the astronauts could watch the comet with telescopes on the space station.

Scientists detected water vapor coming off the comet, confirming long-held theories. And their studies suggested the comet was making its first close pass to the Sun. So while Kohoutek was a P.R. bust, it provided valuable insight into these hard-to-predict objects.
 

Script by Damond Benningfield

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James Webb Space Telescope started out with a bang. Some of its first pictures revealed that the universe was churning out galaxies quite soon after the Big Bang. That pushed the start of galaxy formation much earlier than most astronomers had expected.

The pictures revealed 87 galaxies that look like they formed just 200 million to 400 million years after the Big Bang, which took place 13.8 billion years ago. Astronomers are using other Webb observations to confirm those ages. If even a small fraction of them are correct, the ideas about early galaxy formation may need to be revised.

In a second study, scientists looked at Webb images of 850 galaxies that are at least nine billion light-years away. They compared the pictures to those of the same galaxies snapped by Hubble Space Telescope. Webb has a sharper view, and its instruments are more sensitive to the types of light at which astronomers observe distant galaxies.

Team members found that the Webb pictures showed much more detail in the most-distant galaxies. Many of them were shaped like disks, like our home galaxy, the Milky Way. Others were well-defined balls. That tells us that galaxies were pulling themselves together when the universe was quite young.

Webb’s first images covered only a tiny portion of the sky. So astronomers expect to find many more early galaxies as the telescope takes a deep look at the rest of the universe.
 

Script by Damond Benningfield

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In most calendar systems, two objects play leading roles: the Sun and Moon. Their motions across the sky define the day, the month, and the year.

Yet some calendars have relied on other lights in the sky: the stars. The first appearance of a star in morning twilight told people that it was time to plant or harvest crops, or to move to a warmer climate for the coming winter. Or a star reaching its highest point in the sky at midnight told them that it was time for important rituals.

One of those markers is Regulus, the brightest star of Leo, the lion. It’s to the right or lower right of the Moon at nightfall this evening, and below the Moon before dawn.

Regulus was one of the most important stars of the ancient world. In Persia, it was one of the four “guardians of heaven,” so it was a key marker in the calendar.

And today, Regulus plays a role in the calendar of the Mayan people of Central America — the descendants of the ancient Mayan civilization.

When Regulus stands highest in the sky at midnight — which happens this month — villagers begin preparing the fields for crops. And they start planting mountain corn when the waxing Moon passes by Regulus in March — an important reminder that’s as easy as watching the stars.

Watch Regulus as it pops into view near the Moon in early evening, and stays close throughout the night. It’ll stand just below the Moon before it sets, a little before dawn.
 

Script by Damond Benningfield

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If you happen to be looking at the constellation Cancer in a couple of hundred million years, you might see some fireworks — the merger of two supermassive black holes. Right now, they’re about 750 light-years apart — closer together than any other supermassive black holes within a long way of Earth. They’re spiraling closer to each other, and are expected to merge to form an even bigger black hole.

The black holes are part of a system known as UGC 4211. It’s about 500 million light-years away. Each black hole is more than a hundred million times the mass of the Sun. They’re at the hearts of separate galaxies, which are also merging.

A recent study said the merger should happen in a series of big steps. In the first step, gravitational interactions with stars moving between them will push the black holes closer together. After that, they may keep their distance for a while.

Next, friction with clouds of gas in the galaxies may give the merger a kickstart. And over the final 10 million years or so, the dance of the black holes themselves will produce gravitational waves — ripples in space and time. Those waves carry away energy, which will bring the black holes together — setting off a huge but brief display of fireworks.

Cancer is high in the sky at nightfall. Tonight, it’s above the Moon. UGC 4211 is much too faint to see without a telescope — for now.

Tomorrow: a bright calendar marker.
 

Script by Damond Benningfield

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Astronomers continue to track an asteroid that took a big wallop a few months ago. The observations will tell us more about the asteroid. More important, they could help keep Earth safe from future threats.

Dimorphos is about 500 feet across. On September 26th, the DART spacecraft slammed into it at 14,000 miles per hour. The goal was to change how long it takes Dimorphos to orbit a larger asteroid, Didymos.

That’s important because many asteroids pass close to Earth. Some of them could someday threaten to hit us. One possible way to protect Earth is to ram something into the asteroid, altering its path just enough for it to safely pass us by.

DART was designed to test that technique. Scientists expected the impact to change Dimorphos’s orbit by about 10 minutes. As it turned out, the change was much bigger — about 32 minutes.

Part of the change was due to the impact itself. But the collision also blasted a huge amount of debris into space. That material acted as a jet, giving Dimorphos a big push. It also created a tail thousands of miles long.

Astronomers are studying that debris to learn about the asteroid. And late next year, Europe will send a craft to fly past Dimorphos. It’ll measure the size of the crater gouged by the impact. It’ll also look into the crater to determine the asteroid’s composition and structure — critical information in figuring out how effective DART’s impact really was.
 

Script by Damond Benningfield

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Traveling to any astronomical object beyond Earth takes time. Apollo astronauts left Earth at 25,000 miles per hour, yet it took three days for them to reach the Moon — our closest neighbor. And present-day missions take even longer.

Yet that’s nothing compared to the time it would take to reach the stars — even the closer ones. A couple of examples appear near the Moon tonight — Pollux and Castor, the “twins” of Gemini, with Pollux closest to the Moon.

Pollux is only 34 light-years away. A light-year is the distance light travels in a year — almost six trillion miles. So Pollux is about 800 million times farther than the Moon. An airliner traveling at about 550 miles per hour would need more than 40 million years to get there. And assuming it could maintain a constant speed, even an Apollo spacecraft would take a million years to cover the gap.

Castor is roughly 50 percent farther than Pollux. That means 60 million years by airliner and a million-and-a-half by spacecraft. There’s one caveat, though. Castor is a system of at least six stars, which makes it a little more difficult to measure its distance. So there’s an uncertainty of about three light-years. That means you could spend all that time in transit and find out that you still had hundreds of thousands of years to go — or that you flew past it and had to double back to reach this nearby star.
 

Script by Damond Benningfield

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If you have a few minutes after sunset, it’s well worth stepping outside and peeking at the western sky. That’s the site of a spectacular encounter between Venus and Jupiter, the brightest objects in the night sky after the Moon. They stand side by side, separated by about the width of the Moon. Venus is the brighter of the two.

The planets are quite different. Venus is a ball of rock and metal only a little smaller and less massive than Earth. Jupiter is a ball of gas that’s much bigger and heavier than Earth. Yet both worlds have an effect on our own — a cycle in Earth’s orbit caused by a gravitational tug of war between Venus and Jupiter.

Jupiter is the most massive planet in the solar system, but Venus passes much closer to us. So when you work it all out, they both produce a pretty good tug on our planet. That changes the shape of Earth’s orbit.

Right now, the orbit is pretty close to circular, so our distance to the Sun varies by only about one and a half million miles in either direction. But over a period of about 400,000 years, the pull of Jupiter and Venus makes the orbit more lopsided. That causes the distance to the Sun to vary by about five million miles. That greater range produces a more significant difference in temperatures. And that creates big changes in climate — thanks to the pull of two planets that are staging a beautiful encounter in the evening sky.
 

Script by Damond Benningfield

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The two brightest points of light in the night sky are staging a spectacular encounter. They’re low in the west at nightfall, and set an hour or so later. Venus is the brighter of the two — the “evening star.” Jupiter is a little above it tonight, but they’ll stand side by side tomorrow night — almost touching each other. They’ll stay fairly close for a few nights after that, but the gap will grow wider night by night.

Venus appears so bright because it’s close to Earth, it’s covered by bright clouds, and it’s close to the Sun, so it reflects a lot of sunlight into space.

Thanks to our always-changing viewing angle, the gap between Venus and the Sun will widen over the next few months. As a result, the planet will stand a little higher in the sky each evening until late June. It’ll be moving closer to Earth until August, when it will pass between us and the Sun.

Jupiter, on the other hand, is dropping toward the Sun. It will disappear in the evening twilight next month. Jupiter shines brightly in part because it’s the biggest planet in the solar system — roughly 11 times the diameter of Earth. And it, too, is covered by clouds. But its brightness is limited by its great distance — an average of almost half a billion miles.

Again, look for Venus and Jupiter hanging close together in the western sky not long after sunset — the brightest lights in the night sky.

More about Venus and Jupiter tomorrow.
 

Script by Damond Benningfield

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