StarDate

A trio of bright lights in the dawn sky will become a quartet for the next few days. The crescent Moon will join the planets Venus, Mars, and Saturn. It’ll be a short-lived combo, though, as the Moon will vanish quickly in the dawn twilight.

Venus is the brightest member of the trio. It’s the brilliant “morning star.” It rises in the east-southeast a little before first light. Much-fainter Saturn will stand just below Venus tomorrow, then farther to the lower right over the following days. And even-fainter Mars is off to their right.

The Moon will stand to the right of the trio tomorrow, but will cozy up just below the three planets on Monday. It’ll slide to the opposite side of the trio on Tuesday, and be much farther on Wednesday, just peeking through the glow of the late twilight.

As the Moon slides toward the Sun, its crescent will get thinner and thinner. Tomorrow, the Sun will light up about one-quarter of the lunar hemisphere that faces our way. By Tuesday, though, only about one-tenth will be in the sunshine.

Even as the Moon wanes, though, we’ll still be able to see the entire disk. That’s because it’s lit up by earthshine — sunlight reflecting off of planet Earth. It gives the lunar nightside a ghostly gray appearance. If you look through binoculars, there’s enough light to make out the lunar seas, highlands, and a few craters — a panorama made visible by our own planet.

We’ll talk more about earthshine next week.
 

Script by Damond Benningfield

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Space rocks have flattened forests, blasted giant holes in the ground, and killed off the dinosaurs and other life. They’ve damaged houses and cars, injured a few people, and one — a rock from Mars — might or might not have killed a dog. And there’s even evidence that they’ve killed people.

The records of human fatalities are all at least a century old. Most of them have been found in reliable sources, such as official records of the Chinese and Ottoman empires, although many experts doubt them.

Recently reviewed Ottoman records reported that one man was killed when a rock fell in modern-day Iraq in 1888. And in China, records say the sky “rained iron” in 1341, claiming many victims.

An even bigger rain of meteorites was recorded in China in 1490. Several sources say the shower killed at least 10,000 people. Although present-day scientists doubt the number, they note that giant showers of stones have been confirmed. In 1868, for example, more than a hundred thousand fragments pelted Poland — but there were no reports of deaths.

Recent studies have concluded that an asteroid exploded above Jordan almost 3700 years ago. The blast would have been similar to several seen above Russia in the 20th century, but much more powerful. Researchers say the explosion demolished three cities, which housed 50,000 residents. The area remained abandoned for centuries — the aftermath of a cosmic explosion.

Script by Damond Benningfield

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Quebec has been a cosmic target. The Canadian province has been hit by big asteroids or comets at least nine times in the past 500 million years. The impacts blasted out craters that are up to a few dozen miles in diameter.

There’s no special reason for the universe to pick on Quebec. The province is almost as big Alaska, though, so it’s a big target.

The most obvious impact scar is Manicouagan. Its main feature is a 40-mile-wide ring that’s filled with water — one of the largest lakes on Earth. Known as the Eye of Quebec, it was gouged more than 200 million years ago by an asteroid about six miles in diameter. Some studies have said the impact might have led to the extinction of much of the life on Earth.

Clearwater Lakes is a pair of craters linked by channels. Both still look nice and round, with raised rims. They’re filled with water. For a long time, scientists said the craters formed at the same time, from an asteroid that split in two, or an asteroid and its moon. But recent work says the larger crater formed more than 450 million years ago, with the other created a couple of hundred million years later.

The most recent crater is known as Pingualuit. It’s just 1.4 million years old. It’s a near-perfect circle about two miles across and a quarter of a mile deep. It, too, is filled with water — some of the purest and clearest on Earth — the aftermath of a cosmic boulder hitting the northern tip of Quebec.
 

Script by Damond Benningfield

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On a fine spring day 66 million years ago, the world came to an end. An asteroid the size of a city slammed into the Gulf of Mexico, gouging a giant crater. The impact blasted debris high into the sky, started fires thousands of miles away, and created a giant tsunami. That set off a chain reaction that killed the dinosaurs and most of the other life on Earth.

Scientists have learned a great deal about the event in recent years. One study, for example, looked at fossil-bearing rocks in North Dakota. From that, researchers concluded that the impact took place in spring.

Other studies have examined the crater. Known as Chicxulub, it’s off the Yucatan peninsula. It’s almost a hundred miles across and a dozen miles deep.

One study mapped what happened in the first day after the impact. Within minutes, flowing rock formed a ring of hills around the impact site; the hills were quickly buried by falling debris. An hour after impact, ocean water began filling the crater, bringing more debris. And in less than a day, the “rebound” of the tsunami hit the crater, depositing material from distant lands, including charcoal — evidence of a massive fire.

That was only the beginning of the end, though. Smoke from the fires blocked out the Sun for months or years around the globe. That snuffed out photosynthesis, which led to a collapse of the ecosystem. Within years, much of the life on Earth was gone — victims of a cosmic impact.

More tomorrow.
 

Script by Damond Benningfield

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The United States is working to send astronauts back to the Moon — perhaps by the end of this decade. The eventual goal is to establish a long-term base there.

But the U.S. isn’t alone in its lunar ambitions. Russia and China have announced plans to build their own base on the Moon, in the 2030s. Cosmonauts and taikonauts would study the Moon, set up telescopes, and test the technology for exploring beyond the Moon.

As with American plans, the China-Russia base would begin with a series of robotic missions — orbiters, landers, rovers, and others. A couple of them are scheduled for launch later this year.

Those missions would identify the best site for the base. They’d perfect the technology for making pinpoint landings, so everything gets to the right spot. They’d find resources for the base to use — water ice, for example — and test the technology for processing those resources.

According to early reports, construction would start sometime in the next decade, and the base would be operational within a few years.

The two countries are still making plans, and they’re talking to other countries about joining the effort. And the project will require a lot of new tech, including giant rockets. But it’s working toward an ambitious goal: building a base on the Moon.

The Moon climbs into good view by 1:30 or 2 a.m., and is in the south at first light. The bright star Antares — the heart of the scorpion — is just below it.
 

Script by Damond Benningfield

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There’s a logjam in the southeastern sky at dawn right now. Three planets huddle within a few degrees of each other. And they’ll stay close for a couple of weeks.

The brightest member of the trio is Venus — the “morning star.” It far outshines every other planet and star in the night sky, so you can’t miss it.

On the other hand, you might not realize that it’s a planet — at least not at first glance. It’s so bright that people often mistake it for an airplane with its landing lights turned on. And it’s sometimes reported to authorities as a UFO. If you watch it for a minute or two, though, you’ll see that it doesn’t move compared to the other lights around it.

Venus does move from day to day, though. Right now, it’s dropping toward the Sun in our sky, so it’s changing position relative to the other two planets.

Tomorrow, for example, Mars is close to the right or lower right of Venus. It’s less than one percent as bright as Venus, but its proximity to Venus will help it stand out. At the same time, Saturn is a little farther to the lower left of Venus, and shines a little brighter than Mars.

Over the coming days, Venus will slide away from Mars and pass by Saturn. They’ll be at their closest early next week. After that, Venus will continue dropping toward the Sun, while Mars and Saturn climb away from it. Saturn will pass Mars in a couple of weeks, when they’ll form a tight pairing — continuing the logjam in the dawn sky.
 

Script by Damond Benningfield

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Spring arrives in the northern hemisphere today, at 10:32 a.m. Central Daylight Time. That’s the moment of the vernal equinox, when the Sun crosses the celestial equator — the projection of Earth’s equator on the sky — from south to north. Over the next three months, the Sun will travel ever farther northward, bringing longer, warmer days to the northern half of the planet.

The word “vernal” comes from the Latin word for spring. And “equinox” means “equal nights.” Theoretically, all points on Earth should see equal amounts of daylight and darkness on the equinoxes. But for several reasons, the interval between sunrise and sunset — which should be exactly 12 hours — varies by a few minutes.

The vernal equinox marks the starting point for the system that astronomers use to plot the sky.

They measure the positions of astronomical objects using coordinates called right ascension and declination — the equivalent of longitude and latitude. Right ascension is measured in hours. The point where the Sun crosses the celestial equator on the vernal equinox is designated as zero hours. It’s the equivalent of zero degrees longitude — the line that runs through Greenwich, England.

And just as Earth’s equator marks zero degrees latitude, the celestial equator is designated zero degrees declination. So at the moment of the vernal equinox, the Sun stands at celestial coordinates zero-zero — beginning a new circle through the stars.
 

Script by Damond Benningfield

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The two stars that make up Spica — the brightest star of Virgo — are monsters. Both are much bigger, brighter, and heavier than the Sun. That means they’ll have much shorter lifespans than the Sun. And the heavier of the two stars should end its life as a supernova — a titanic explosion that will rip it to bits.

But the fate of the second star isn’t quite as certain. It probably will end as a white dwarf — the same fate that awaits the Sun. But there’s a bit of wiggle room in the numbers. And that leaves the possibility that it, too, could become a supernova.

The main factor is the star’s mass. Most models of how stars work say that a star that’s at least eight times the mass of the Sun will expire as a supernova. And the smaller star of Spica — known as Spica B — appears to be a little more than seven times the Sun’s mass — below the line.

But there’s some wiggle room. Spica B could be right at eight times the Sun’s mass — just heavy enough to go “boom.” There’s also some wiggle room in the models — the lower limit of eight times the Sun’s mass isn’t a hard and fast number. And it’s hard to calculate how the other star will affect Spica B’s evolution. So while Spica B probably won’t light up the skies as a supernova, it’s not out of the question.

Look for Spica — the combined light of two monster stars — near the Moon tonight. It’s close to the lower right of the Moon as they climb into good view, by 10 or 10:30.
 

Script by Damond Benningfield

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Ideas about the planet Venus are sort of like children on a seesaw: up, then down; up, then down.

Astronomers have known for a long time that Venus is covered by clouds. Until the 1960s, that raised the possibility that the surface was covered by oceans and steamy jungles, both teeming with life. That’s up.

As spacecraft began visiting Venus, though, we learned that the clouds are made of sulfuric acid, and conditions below them are hellish. The atmosphere is made of carbon dioxide, it’s dense enough to squish living organisms, and it’s hot enough to melt lead. That’s down.

Then, a few decades ago, evidence began to suggest that Venus had been covered by oceans for as long as two billion years. That would have created a comfortable home for life. Back up.

But a study released last year said that Venus was never cool enough to form oceans, so it’s always been hot and dry. Back down.

Our knowledge of the planet’s past is limited, though, because probes have barely touched the surface. Missions scheduled for the next decade or so should spend more time exploring the surface. Their findings could tilt the seesaw once more — but in which direction is still a mystery.

And Venus has tilted up into view in the dawn sky. It’s the brilliant “morning star,” low in the southeast at first light. Right now, fainter Mars is close to the lower right of Venus — another world with its ups and downs. But that’s a tale for another day.
 

Script by Damond Benningfield

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In modern mythology, dragons are known for breathing fire. And a couple of years ago, a young star in the dragon constellation did just that. It blasted out the biggest eruption yet seen from a Sun-like star.

EK Draconis is in Draco, the dragon. The star is low in the northern sky as night falls. It’s about the same size and mass as the Sun, but it’s more than a hundred light-years away, so you need a telescope to see it.

Astronomers have kept a close eye on the star for decades. They’ve known that it’s a lot more “active” than the Sun — it produces more outbursts of energy and particles. Even so, an outburst in April of 2020 was a knockout. It first produced an explosion known as a superflare. That was followed by a coronal mass ejection — a massive blast of charged particles. It was 10 times more massive than anything ever seen from the Sun. It raced outward at a million miles per hour.

The key to the outburst probably is the star’s age. EK Draconis is only about a hundred million years old — about two percent of the Sun’s age. Young stars generally rotate much faster than older ones. That generates a much stronger magnetic field — and more powerful eruptions.

It’s lucky for us that the Sun is older and calmer. If it produced an outburst like the one from EK Draconis, it could fry our power grids, plunging much of the world into darkness. So, in this case, middle age has its advantages over the fiery nature of youth.

Script by Damond Benningfield

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