The asteroid that killed the dinosaurs might have had some help. A crater discovered off the coast of Africa formed at about the same time as the one gouged by the dinosaur killer. That suggests they could have been companions — perhaps formed by pieces of a larger asteroid.

Much of the life on Earth died when a miles-wide space rock slammed into our planet 66 million years ago. The impact formed a crater in the Gulf of Mexico. Known as Chicxulub, it’s more than a hundred miles wide. Debris that was blasted into the air blotted out the Sun and caused acid rain around the globe.

A couple of years ago, researchers were studying the floor of the Atlantic Ocean when they discovered a new crater near Africa. It’s only five or six miles wide. The asteroid that created it was about a quarter of a mile in diameter. The impact would have produced a massive fireball, vaporized rocks and ocean water, and triggered tsunamis.

The crater formed at about the same time as Chicxulub. So the asteroids that created them could have been companions — perhaps fragments of a single asteroid that broke apart when it reached Earth. Or perhaps the parent asteroid broke apart much earlier, with the two pieces hitting Earth at different times. Or perhaps it’s just a coincidence, and the two asteroids were unrelated.

Scientists plan to drill into the crater to learn exactly when it formed — telling us whether a dinosaur killer had some help.

Script by Damond Benningfield

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Many of the myths of ancient Greece sound like they were written for Hollywood. There’s beauty, mystery, and treachery, with enough nasty monsters to occupy hordes of computer animators. One of the nastiest is Cetus, the sea monster, which crawls across the southern sky on November evenings.

His story begins with Cassiopeia, the queen of Ethiopia. She was beautiful but vain — she bragged that she was the most beautiful of all. That didn’t sit well with the sea nymphs, who were also great beauties. They asked their father, Poseidon, to punish Cassiopeia for her boasting. He did, by sending Cetus to destroy the kingdom.

Cetus often is depicted as having the head and front legs of a land creature, but the body of a sea serpent. And he was huge — big enough to flatten villages.

The oracles told King Cepheus that the only way to save his kingdom was to sacrifice his daughter, Andromeda. So he ordered her chained at the shoreline.

Just as the monster approached, though, Perseus the hero came to the rescue. Depending on which version of the tale you read, he either hacked the monster up or turned him to stone with the head of Medusa, another nasty creature. Either way, Andromeda was saved, and Cetus was banished to the stars.

The constellation is climbing into view in the southeast at nightfall, and is in full view an hour or so later. But it has few bright stars, so you need dark skies to see this giant sea monster.

Script by Damond Benningfield

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Cassiopeia the queen stands high in the northeast at nightfall. Some of her stars form a giant letter M or W. 450 years ago this week, a brilliant new star appeared near the center point of that letter.

Today, it’s known as Tycho’s Supernova, for Tycho Brahe, who published an extensive study of it. But it might also be called Hamlet’s Supernova. A study a few years ago suggested the star might have inspired William Shakespeare to write the famous play.

The star appeared in 1572, when Shakespeare was eight years old. It became as bright as Venus. It flared into view when a “dead” star stole gas from a companion star, causing the dead star to explode.

At the time, the heavens were considered unchanging. A bright “new” star popping into view shook up that concept. The idea that Earth was the center of the universe also was changing, creating a time of uncertainty. And change and uncertainty are a theme in Hamlet, which was written around 1600.

A few years ago, a team led by Don Olson at Texas State University suggested the play was inspired by the supernova. Dialogue suggests it was set in November, and references a star that “burns” near the spot of the supernova. The play is set near Tycho’s observatory. And astronomy played a role in other Shakespeare plays.

There’s no “smoking gun” to confirm the idea. But it suggests that one of history’s great works of art could have been inspired by a great work of nature.

Script by Damond Benningfield

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Tycho Brahe was one of the greatest observers of the night sky. In the era before telescopes, he compiled some of the most accurate star catalogs in history. It didn’t take a lot of talent for him to notice a bright new star in Cassiopeia, though. Tycho logged it 450 years ago tonight. He studied the star extensively, so today it’s known as Tycho’s Supernova.

At the time, the heavens were considered not only unchanging, but unchangeable. A new star suddenly flaring to life didn’t fit that model at all. It helped create a revolution in our understanding of the universe.

It took centuries for astronomers to figure out what had created the new star: a supernova. A “dead” star known as a white dwarf had pulled gas off the surface of a companion star. Eventually, so much gas piled up on the white dwarf that it caused a runaway nuclear explosion. That blasted the white dwarf to cosmic dust.

The supernova was extremely bright. It eventually got as bright as Venus, the brightest object in the night sky after the Moon. And it remained visible for a year and a half.

Today, the debris from that explosion forms a bubble of gas and dust. It’s expanding at two or three percent of the speed of light.

The bubble is too faint to see without a telescope. But you can easily spot its location. It’s close to the left of the center point of the “W” that outlines Cassiopeia, high in the northeast at nightfall.

Script by Damond Benningfield

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A couple of bright orange dots accompany the gibbous Moon across the sky tonight: the planet Mars and the star Aldebaran. Mars is the brighter of the two, and rises close to the lower left of the Moon. Aldebaran is farther to the right of the Moon. They’re all in good view by about 8 o’clock.

Mars and Aldebaran appear orange for different reasons. Mars is “rusty” — it’s covered by dust that contains a lot of iron, which has a dark orange color. Aldebaran is orange because its surface is fairly cool, and cooler gas looks redder than hotter gas.

Mars is about eight times brighter than Aldebaran right now. Aldebaran’s brightness doesn’t really change. The star is so far away that any changes in its distance are insignificant.

But Mars is in our own solar system. It’s the next planet out from the Sun. So over a couple of years, its distance from Earth varies by a wide margin — from a maximum of almost 250 million miles to a minimum of less than 40 million.

Now, Earth and Mars are heading toward one of those close encounters. On December 1st, they’ll pass about 50 million miles apart. And as Mars gets closer, it gets brighter. At its brightest, the only objects in view in the night sky that will outshine it will be the Moon and the planet Jupiter.

Mars and the Moon will move closer to each other during the night, and will appear to almost touch each other at dawn. They’ll remain close tomorrow night.

Script by Damond Benningfield

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You won’t find a much quieter place in the solar system than the far side of the Moon. The Moon doesn’t produce any radio noise, and it blocks radio signals from Earth. That could make it a good site for radio telescopes. But it’ll take a lot of work to build them — and to keep the farside nice and quiet.

Radio telescopes are needed to study the Dark Ages — the period in the early universe when the first stars and galaxies were taking shape. The energy from that era is visible mainly at radio wavelengths. But Earth produces huge amounts of interference — from cell phones to orbiting satellites to microwave ovens. That overwhelms the whispers of the universe.

So astronomers are drafting plans for radio telescopes on the Moon. But the farside is about to get a lot louder. New orbiters and landers will broadcast from there, making it much less favorable for astronomy.

Scientists are trying to get international treaties to limit farside broadcasts. They want to set up a “quiet zone” where no signals at scientifically interesting wavelengths would be allowed. No one knows yet if they’ll succeed at keeping the far side of the Moon quiet.

The Moon is just a couple of days past full tonight, so it’s nice and bright. The star Aldebaran, the eye of the bull, rises close to its lower right, and will be to the lower left of the Moon at dawn.

More about the Moon, Aldebaran, and another bright companion tomorrow.

Script by Damond Benningfield

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Thousands of planets have been found in other star systems. They’re all so far away, though, that most are no more than squiggly lines on a computer screen. Yet scientists are slowly teasing the details out of the squiggles.

To understand how difficult the problem is, consider that there’s still a lot to learn about the planets of our own solar system.

One mystery, for example, is why the planet Uranus radiates very little energy into space.

The four outermost planets — Jupiter, Saturn, Uranus, and Neptune — are all giants. They’re so massive that gravity tightly squeezes their insides, producing heat that radiates into space. In fact, three of the four emit a lot more energy than they receive from the Sun. The exception is Uranus, where the energy is roughly balanced — and scientists are trying to figure out why.

Another mystery is the planet’s climate. Uranus lies on its side, with each pole receiving 42 years of sunlight followed by 42 years of darkness. Astronomers are watching how the climate changes with the seasons — one of the mysteries of a world in our own neighborhood.

Uranus is passing closest to Earth about now, so it’s biggest and brightest for the year. Even so, you need binoculars to spot it — especially tonight. It’s low in the east as night falls, close to the upper right of the full Moon.

We’ll talk about the Moon and a much brighter companion tomorrow.

Script by Damond Benningfield

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For the third November in a row, Earth, Moon, and Sun will achieve syzygy — a perfect alignment. The Moon will pass through Earth’s shadow, creating a total lunar eclipse. All or most of the eclipse will be visible from the entire United States.

“Syzygy” comes from a Greek word that means a union — like when two horses or oxen are yoked side by side. And several times each year, Earth, Moon, and Sun are locked in a precise alignment — a “union” that results in either a lunar or solar eclipse.

This eclipse gets underway shortly after 3 a.m. Central Time. That’s when the edge of the Moon begins to enter Earth’s dark inner shadow, known as the umbra. That begins a partial eclipse, with the Moon partially in the shadow and partially bathed in sunlight.

The Moon will be fully immersed in the shadow — beginning the total eclipse — a little more than an hour later. Totality will last for almost an hour and a half. After that, the eclipse will become partial again as the Moon begins to leave the shadow behind. It ends a few minutes before 7.

Skywatchers west of a line from the southern tip of Texas to the western tip of Lake Superior — including all of Alaska and Hawaii — will see the entire total eclipse and most of the partial. Most of those to the east of that line will see all of the total eclipse, but the Moon will set during the partial phase — the end of a perfect alignment.

Script by Damond Benningfield

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It’s eclipse season! There was a partial solar eclipse a couple of weeks ago. And on Monday night, we’ll have a total lunar eclipse. That one will be visible across all of the United States.

It’s not a coincidence that the eclipses are taking place two weeks apart. In fact, eclipses always come in pairs — unless they come in threes — and always two weeks apart.

That’s because eclipses require precise alignments of Earth, Sun, and the new or full Moon. But the Moon’s orbit around Earth is tilted a bit compared to Earth’s orbit around the Sun. So most months, when the new or full Moon crosses Earth’s orbit it’s either above or below the point where it would create an eclipse.

When the Moon crosses Earth’s orbit at just the right time, though, it brings Moon, Earth, and Sun into alignment. In fact, the alignment happens twice, about two weeks apart — an eclipse season. One alignment creates a solar eclipse, while the other creates a lunar eclipse. They can happen in either order. And the cycle repeats roughly six months later.

The total length of an eclipse season is about five weeks. So if there’s an eclipse early in that period, there can be a third eclipse at its end — usually two poor eclipses flanking one good one. And if the year’s first eclipse season begins in early January, there can be three of them during the year — producing as many as seven eclipses — which will happen in 2038.

More about the upcoming eclipse tomorrow.

Script by Damond Benningfield

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Black swifts love moonlight — the brighter the better. A recent study found that the birds climbed to their highest altitudes when the Moon was full. But when the moonlight was blocked by an eclipse, they dropped in a hurry.

Researchers attached small trackers to a group of black swifts in Colorado. They then tracked the birds during their 4,000-mile migration to the Amazon Basin in Brazil. It took about eight months for the small birds to make the trip — with more than 99 percent of their time spent in the air.

During the day, and on nights with little moonlight, the birds stayed at altitudes of a few hundred to a few thousand feet. When the Moon was full though, they soared to two or three miles — possibly to grab high-flying insects.

On the night of January 20th, 2019, the birds were flying when the Moon was eclipsed. And they didn’t seem to like it. They quickly dropped thousands of feet. And when the eclipse ended, they climbed higher again.

This isn’t the first time animals have been seen to change behavior during an eclipse. Animals that like the light tend to slow down—including mosquitoes—while those that prefer the dark tend to get more active.

The black swifts usually head southward around September. So depending on where they are right now, they might experience that roller-coaster ride again soon. That’s because there’s a lunar eclipse coming up on Monday night. More about that tomorrow.

Script by Damond Benningfield

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