StarDate

The heart of the galaxy Messier 87 is a cosmic maelstrom. A disk of super-heated gas that’s hundreds of times the size of our solar system encircles a monster black hole. Gas at the inner edge of the disk spirals into the black hole, producing huge amounts of X-rays. Enormous magnetic fields channel some of the gas into powerful “jets.” It’s not a place you’d ever want to visit. But it’s a fascinating region to study from far away. M87 is a giant elliptical galaxy. It looks like a fat, fuzzy rugby ball. It’s bigger than our home galaxy, the Milky Way. It has many more stars, and could be up to 200 times as massive as the Milky Way. The black hole at its heart is impressive, too. It’s roughly 1400 times the mass of the black hole at the center of the Milky Way. It’s pulling in gas, dust, and other debris. That material forms a disk that’s hundreds of times wider than the orbit of Neptune, the Sun’s most-distant planet. A recent study found that material in the disk is falling into the black hole at a quarter of the speed of light. And the black hole itself is rotating at 80 percent of lightspeed or faster. That rotation generates a powerful magnetic field. The field catches some of the infalling material and shoots it back into space. That creates a “jet” of charged particles that’s thousands of light-years long – a beam of deadly radiation from the heart of Messier 87. Script by Damond Benningfield

A galaxy cluster is like a cosmic blender. It stirs up the galaxies and the space between them. Nothing is left undisturbed. A perfect example is the Virgo Cluster. It consists of more than 1500 individual galaxies, centered about 55 million light-years away. Most of them are fairly small and faint. But a few are monsters – many times the size and mass of our home galaxy, the Milky Way. The cluster’s galaxies are packed fairly close together. So the gravity of each galaxy pulls at its neighbors. That distorts the shape of some of the neighbors, making them lopsided. It also causes big clouds of gas to collapse and give birth to new stars. And it pulls many stars out of the galaxies, into the space between them. In fact, up to one-tenth of the stars in the cluster may be roaming through intergalactic space. The cluster’s brightest galaxy is Messier 49. It was the first to be discovered, in 1771. It’s a giant elliptical, so it looks like a fat, fuzzy rugby ball. It’s much bigger than the Milky Way, and many times its mass. And a supermassive black hole inhabits its heart. The biggest and heaviest member of the cluster is Messier 87, and we’ll talk about it tomorrow. The Virgo Cluster is centered along the border between Virgo and Leo. That spot is low in the east at nightfall and climbs high across the sky later on. Many of the galaxies are easy targets for small telescopes. Script by Damond Benningfield

Snow blanketed the launch pad, and the rocketeers sipped hot malted milk to ward off the chill. But the launch they conducted a century ago today turned the idea of space travel from fantasy to possibility – and provided the first small step toward the Moon. The rocket was designed by Robert Goddard, a physics professor at Clark University in Massachusetts. Goddard was brilliant but secretive. He refused to collaborate with other scientists, and seldom even talked about his research. Instead, he spent his time building, testing, and flying rockets. At the time he started, all rockets were powered by solid fuels, such as gunpowder. But solid fuels are inefficient and hard to control. So Goddard built a rocket powered by liquid fuels – gasoline and liquid oxygen. It was a potent mixture that provided far more energy per pound than solids. Goddard and his wife and assistants launched the first liquid-fueled rocket in history on March 16th, 1926. It was airborne for just two and a half seconds, and climbed just 41 feet. But it proved that liquid fuels could propel a rocket skyward. Goddard spent two more decades experimenting with rockets. German engineers used many of his innovations in the V-2, which bombarded England during World War II. Transplanted to the United States after the war, many of these engineers developed the rockets that boosted satellites into space – and sent astronauts to the Moon. Script by Damond Benningfield

A three-way tug-of-war isn’t a common sight – unless you look toward the constellation Leo. Three galaxies there are tugging at one another, producing some spectacular results. The galaxies are M65, M66, and NGC 3628 – the Leo Triplet. All three galaxies are about the same size as our home galaxy, the Milky Way. And each may resemble the Milky Way – a beautiful spiral with a long “bar” of stars across its middle. The triplets are close enough together that the gravity of each galaxy exerts a strong pull on the others. That’s given M66 a slightly “wonky” look. The galaxy’s core is a little off-center. Its spiral arms are loosely wound, and they aren’t symmetrical. And the arms are lined with knots of starbirth. Some of the stars in these regions are huge. Such a star burns out quickly, then explodes as a supernova. And since 1973, we’ve seen five supernovas in M66 – compared to zero in the Milky Way. We see NGC 3628 edge-on, so it’s hard to know its exact shape. What we do see is a lane of dark dust sandwiched between brighter layers. We also see a “tail” that’s 300,000 light-years long – three times the size of the galaxy itself. It’s a ribbon of stars pulled out by the other galaxies in their ongoing “tug-of-war.” Leo is in the east at nightfall. The triplet is to the upper right of Denebola, the star at the lion’s tail. It’s an easy target for a small telescope. Script by Damond Benningfield

It sounds like a toddler’s attempt to say “Friday” or, even better, a day to gorge on apple crumb or coconut cream. Alas, “Pi Day” is something completely different. It’s a commemoration of a mathematical constant that’s represented by the Greek letter pi – one of the most important quantities in science. Pi is the ratio of a circle’s diameter to its circumference. When it’s rounded off to two digits, it’s 3.14 – the numerical equivalent of March 14th. Astronomers use pi to calculate the volume and density of a star or planet, the details of an orbit, and much more. Other scientists use it as well. But pi is an “irrational” number. That means that no matter how long you calculate its exact value, you never reach the end – whether you go to a thousand decimal places, a million, or rbrm eleventy-jillion. There’s never a conclusion, and no group of numbers ever repeats. Mathematicians have used various techniques to try to calculate the exact value, without success. The record so far is more than a hundred trillion places to the right of the decimal. Trying to calculate an exact value has been an important plot point in science fiction. Any time a computer is getting too uppity, it’s commanded to calculate pi to the last digit. That impossible task overloads the computer, allowing the heroes to regain control. Whether we’ll need it to rein in A-I – well, have a slice of pie – the tasty variety – while you ponder it. Script by Damond Benningfield

To the eye alone, the brightest star in the night sky is Sirius, the leading light of Canis Major, the big dog. It’s well up in the south at nightfall – a brilliant beacon less than nine light-years away. If we could shift the sensitivity of our eyes to shorter wavelengths, the brightest star would appear a little below Sirius. Adhara is already the second-brightest star in the constellation. But it produces most of its energy in the extreme ultraviolet – wavelengths that are far too short to see with the human eye. At those wavelengths, Adhara would be the brightest object in the entire night sky. The star is an ultraviolet powerhouse because it’s tens of thousands of degrees hotter than the Sun. The hotter an object, the more U-V it produces. And Adhara is huge – more than 10 times the Sun’s diameter. So there’s a lot of real estate for beaming its radiation into space. The U-V zaps molecules of gas and dust anywhere close to the star, splitting them apart and making them glow. But the star has been around long enough that it’s already cleared out most of the space around it. More than four million years ago, Adhara was much closer to the Sun than it is today. That made it the brightest star at visible wavelengths as well. It shined as brightly as Venus, the morning or evening star. But Adhara’s motion through the galaxy has carried the star much farther from us – allowing Sirius to outshine this sizzling star. Script by Damond Benningfield

For Charles Messier, star clusters were a nuisance. The French astronomer was mainly interested in comets. In the 18th century, finding a comet could bring fame and fortune – kings sometimes awarded medals and fat stipends for their discovery. Through a telescope, star clusters could resemble comets. Messier and others might spend time following a cluster, only to find out that it wasn’t the prize. So Messier compiled a catalog of clusters and similar nuisances – a list of objects to ignore. Four of the clusters follow a narrow path near Canis Major, the big dog: M46, 47, 48, and 50 – a Messier “highway.” Although they’re close together in our sky, the clusters are not close together in space. Their distances range from about 1600 light-years to more than five thousand. So there’s no relationship among them. They appear close together because they all lie along the Milky Way – the glowing outline of the disk of the Milky Way Galaxy. In that direction, we’re looking into the most densely populated region of the galaxy, so we see many more stars and star clusters – including the “pesky” clusters cataloged by Charles Messier. The clusters are in the southeastern quadrant of the sky as night falls. Look for Sirius, the brightest star in the night sky, due south. The clusters spread out to the left and upper left of Sirius. All of them are easy targets for binoculars. Script by Damond Benningfield

Winter brings out the big dogs – some of the most prominent constellations of all. And one of those really is a dog: Canis Major, the big dog. It’s best known for Sirius, the Dog Star – the brightest star in the night sky. It’s a third of the way up the southern sky at nightfall. But there’s much more to Canis Major than just Sirius. It includes several bright stars, most of which are below or to the right of Sirius. When you link them up, they do form the outline of a dog. Like all constellations, Canis Major consists of more than just a connect-the-dots pattern of stars, though. It covers a patch of sky that includes everything within its borders. And in that area, you can find several deep-sky objects – objects like star clusters, which are far beyond most of the individual stars visible in Canis Major. Perhaps the best known is Messier 41. It’s not far below Sirius, and it’s an easy target for binoculars. It’s about 2300 light-years away, and includes a hundred or more stars. The cluster probably is about 200 million years old. At that age, its biggest, heaviest stars have expired. They’ve left behind small, dense corpses known as white dwarfs. The next-heaviest stars soon will follow the same path. Those stars have puffed up to become red giants. They’re easily visible through binoculars – sparkling red and orange jewels along the “collar” of the big dog. More about Canis Major tomorrow. Script by Damond Benningfield

A magazine that first hit newsstands 100 years ago today was unlike anything readers had seen before. Its cover featured a brightly-colored painting of people ice-skating on a comet as it zoomed past Saturn. Its founding editor, Hugo Gernsback, called it “a new sort of magazine” – “a magazine of ‘scientifiction'” – a genre known today as science fiction. Amazing Stories was the first magazine dedicated solely to the genre. Its debut issue, which was dated April 1926, carried reprints of stories by Jules Verne, H.G. Wells, Edgar Allen Poe, and others. The story titles included “The Man from the Atom” and “The Thing from – Beyond.” The magazine was an instant hit. Within a year, monthly circulation was at 150,000. Other publishers quickly caught on, and began publishing many more sci-fi magazines. Over the decades, they included such titles as Fantastic, Astonishing, and Astounding. They featured many of the major figures of science fiction’s “golden age.” Their inventive stories and eye-catching covers caught the attention of lots of youngsters. The magazines inspired many of them to pursue careers in astronomy, physics, engineering, and related fields. They also inspired future filmmakers, who expanded “scientifiction” far beyond the printed page. Few science-fiction magazines have survived. But their influence is still felt today – on Earth – and beyond. Script by Damond Benningfield

A future super-giant “onion” perches close to the Moon at dawn tomorrow. It’s the star Antares, the bright heart of the scorpion – one of the most impressive stars in the galaxy. Antares is a supergiant. It’s roughly a dozen times as massive as the Sun, and hundreds of times wider. Because it’s so heavy, gravity squeezes its core tightly. That revs up the nuclear fusion in the core. Like all stars, those reactions initially fused hydrogen to make helium. In the Sun, hydrogen fusion will last about 10 billion years. In Antares, though, it lasted a little more than 10 million years. When the hydrogen in the core was gone, the core shrank, making it hotter – hot enough for the helium to fuse to make carbon and oxygen. That process will last about one million years. Then the carbon will fuse to make heavier elements, and so on. Each step takes less time than the one before. In the final step, silicon will fuse to make iron – a step that takes just a few days. The lighter elements won’t all go away, though. Instead, the “ash” from each step will form layers around the core – like an onion. But that structure won’t last. The core can’t get hot enough to fuse the iron. Gravity will win out, and the core will collapse – forming an ultra-dense neutron star. Everything outside the core will blast outward at a few percent of the speed of light. Supergiant Antares will explode as a supernova – an impressive end for an impressive star. Script by Damond Benningfield

Canopus would be a terrible neighbor. The star is big, bright, and hot, so it might blow away any planet-making materials around nearby stars. Even worse, it may be destined to explode. That would zap any existing planets with radiation – perhaps endangering any life in nearby star systems. Canopus is the second-brightest star in the night sky. At this time of year, it’s visible from the southern third of the United States in early evening. It’s low in the south, well below Sirius, the brightest star. Canopus is at least eight times the mass of the Sun. So even though it’s billions of years younger than the Sun, it’s already completed the main phase of life. Within a few million years, its core will collapse, perhaps forming an ultra-dense neutron star. If so, then its outer layers will blast into space as a supernova. Such an outburst would produce enormous amounts of X-rays and gamma rays – the most powerful forms of energy. That could strip away the ozone layer of any planet within a few dozen light-years, subjecting the surface to high levels of radiation. So far, we know of only one planet within that range where conditions are most suitable for life. The planet itself isn’t likely to host life. But any big moons might be more comfortable homes – at least until the demise of Canopus. Luckily for us, Canopus is 300 light-years away. So Earth is well outside the “danger zone” of this not-so-neighborly neighbor. Script by Damond Benningfield

The tale of Jason and the Argonauts is one of the biggest and boldest stories in Greek mythology. And it involves some of the greatest heroes, many of whom are depicted in the stars – from the twins of Gemini to mighty Hercules. The boat itself was placed in the stars as well. But even it was too big. Astronomers eventually split it apart. The original constellation was Argo Navis. It was first drawn almost 3,000 years ago. It was far larger than any of the other ancient western constellations. And for a long time, that was just fine. But as astronomers began studying the stars with telescopes, the Argo was just too big – there were too many stars and other objects within its borders to catalog. In 1756, French astronomer Nicolas Louis de Lacaille decided to do something about it. He split the Argo apart. He kept the references to the boat, though. So his new constellations were Carina, the keel; Vela, the sail; and Puppis, the poop deck – the deck at the back of the boat. And those constellations are still in use today. Carina is best known for its brightest star, Canopus. It’s the second-brightest star in the night sky. And from the southern latitudes of the United States, it crawls low across the south in early evening at this time of year. As night falls, it’s just above the horizon, almost directly below Sirius, the brightest nighttime star. We’ll have more about Canopus tomorrow. Script by Damond Benningfield

The first ship in a solar-system armada reached its target 40 years ago today. Over the following week, four others joined it. Their target was Comet Halley. It was making its first passage through the inner solar system since 1910. So it was the first chance to study the comet from close range. And space agencies around the world responded. The Soviet Union and Japan each sent two spacecraft, and Europe added one more. The first to arrive was Vega 1, one of the Soviet missions. It and a companion, Vega 2, had first flown past Venus. They scanned the planet and dropped probes into its atmosphere. Both of them flew just a few thousand miles from Halley’s nucleus – its “body” of rock and ice. Europe’s contribution, Giotto, came even closer – just 370 miles. It snapped by far the best pictures of any comet. It found that most of the nucleus was covered by a “crust” that was darker than charcoal. But “jets” of ice and dust erupted from thin spots in the crust. They wrapped the nucleus in a cloud of debris. Sunlight and the solar wind pushed some of that material away from the comet, forming a tail that was millions of miles long. The United States was a notable no-show. A dedicated mission to Halley was scuttled. NASA did turn some craft that were already in space to face Halley, but they were millions of miles away. The next chance to study the comet up close won’t come until 2061. Script by Damond Benningfield

Visitors sometimes just drop in on us. But a visitor to a home in Georgia took the notion of “dropping in” a bit far. It smashed through the roof, an air duct, and a thick layer of insulation before splatting into the floor, leaving a crater the size of a quarter. It missed smacking into a resident by just 14 feet. The “visitor” was a meteorite – part of a much larger space rock. The rock formed a glowing streak as it raced through the skies of the southeastern United States on June 26th. Hundreds of people saw it, and many more heard it – it produced a sonic boom, plus an explosion before it hit the ground. The bit that smashed into the house was one of more than 200 samples recovered. In all, they totaled about 12 pounds. Collectively, they were called the McDonough meteorite for the small town where they hit. Eyewitness reports, videos, weather radar, and weather satellites helped scientists reconstruct the space rock’s origin. It came from the asteroid belt – a wide band of debris between the orbits of Mars and Jupiter. It probably was a piece from a much larger body that broke apart 470 million years ago. Lab studies revealed the meteorite’s age: 4.56 billion years – about 20 million years older than Earth. That means it was similar to the rocky building blocks that came together to make Earth. So the McDonough meteorite is an ancient visitor that dropped in with a bang. Script by Damond Benningfield

Last July, a space telescope heard the death cry of a star billions of light-years away. It was the longest outcry of its type ever detected – an astonishing seven hours. Yet its details are still fuzzy. All we know for sure is that it was a violent ending for a star. The outcry was a gamma-ray burst. Astronomers have discovered thousands of them. They’re usually produced by a supernova – the titanic explosion of a massive star. Energy from the nuclear inferno deep inside the star blasts outward through its poles. That forms narrow jets of gamma rays – the most powerful form of energy. The gamma rays usually last a few seconds or minutes. In that time, though, the burst can emit more energy than the Sun will produce over billions of years. Follow-up observations showed that the July outburst took place in a galaxy that’s giving birth to many stars – perhaps as the result of a merger with another galaxy. Many of the new stars are hot and massive, so they explode quickly. That makes the galaxy a good breeding ground for gamma-ray bursts. But the origin of this event isn’t clear. It could have been the result of a supernova. Other possible scenarios include the merger of a black hole with the dead or stripped core of a Sun-like star, or a close encounter between a star and a mid-sized black hole. Such an encounter would have ripped the star apart, forming a trail of incandescent gas – triggering a long outcry from a dying star. Script by Damond Benningfield

Two of the planets of the solar system are crossing paths in the early evening. But they’re quite low in the sky, so they can be a bit tough to spot. The brighter of the two is Venus, which is beginning its reign as the “evening star.” It’ll climb higher into the sky over the coming weeks and months, making it much easier to spot. Right now, though, it sets by the time the color of twilight drains away, so there’s not much time to enjoy it. Venus’s companion is Saturn. It’s close to the upper left of Venus. It’s only about one percent as bright, so it’s tougher to pluck from the twilight. You might miss it entirely if not for the presence of its brighter sibling. And the two planets really are siblings. They were born from the same cloud of gas and dust that surrounded the newborn Sun. Venus was born close to the Sun. Conditions in that region were so hot that only heavier materials were available to build planets. So, like Earth, Venus is made mostly of rock and metal. Saturn took shape in the deep-freeze of the outer solar system. The planet built a big core of heavy materials. The core then pulled in huge amounts of gas. That made Saturn the second-largest planet – a cold, gassy world far from the Sun. Watch Venus and Saturn as they cross paths the next few nights. They’ll stand side by side on Saturday, just a whisker apart. Venus will pull away after that, with Saturn vanishing in the sunlight. Script by Damond Benningfield

Life is all about cycles: birth and death, the rise and fall of the seasons, Taylor Swift tour eras. Many cycles play out in the sky as well. One of them is in view in the wee hours of tomorrow morning, as the Moon and Sun stage a total lunar eclipse. All or most of it will be visible across most of the United States. A lunar eclipse occurs when the Moon passes through Earth’s long shadow. The Moon’s orbit is tilted a bit, so most months the Moon passes above or below the shadow. When the geometry is just right, though, it plunges through this cone of darkness. Each eclipse is part of a centuries-long cycle, known as a Saros. Individual eclipses in a Saros are separated by about 18 years. Tonight’s eclipse is the 27th of 71 eclipses in this cycle. The previous eclipse in the cycle took place in 2008, with the next in March of 2044. But several Saros cycles are unspooling at the same time, so Earth sees two or more lunar eclipses every year. Totality – when the Moon is fully immersed in the shadow – will last about 58 minutes. Alaska, Hawaii, and much of the West Coast will see the entire eclipse sequence. That includes the partial phases, as the Moon moves into and out of the shadow. Much of the rest of the country will see all of the total eclipse, and most of the partial phases, with the Moon setting before the eclipse ends. Script by Damond Benningfield

The Moon stalks the heart of the lion tonight. And seen from Hawaii, it’ll catch it. The Moon will “occult” the heart, blocking it from view. The lion’s heart is Regulus, the brightest star of Leo. The name Regulus means “the little king.” It was introduced 500 years ago. But the star’s association with royalty goes back much farther. In ancient Persia, Regulus was one of the four “royal” stars – four especially bright stars near the ecliptic – the Sun’s path across the sky. The stars are roughly evenly spaced around the ecliptic. That means each star is at its best during a different season. So each star was considered the “guardian” of its season. Regulus is closer to the ecliptic than the other three guardians, so it was the most important of them all – a king among kings. The Moon stays close to the ecliptic as well, straying only a few degrees to either side. So it circles past the same stars every month – including Regulus. Right now, the Moon’s path carries it especially close. And that’s easy to see tonight. Regulus is below the Moon as night falls. But as the hours roll by, the Moon will creep closer and closer to the bright star. As seen from the continental United States, they’ll be separated by no more than about one degree as they set, before dawn – the width of a pencil held at arm’s length. And from Hawaii, the Moon will catch the star – “eclipsing” the little king. Script by Damond Benningfield

The planets in our solar system fit into two groups. Four of the planets are small and rocky; Earth is the largest. The other four are big and bloated; Neptune is the smallest. But there’s nothing between the sizes of Earth and Neptune. And that’s a bit odd. Two of the most common types of planets elsewhere in the galaxy are somewhere in the middle: super-Earths and mini-Neptunes. Astronomers have confirmed more than 6,000 planets in other star systems. Only one system has as many known planets as the solar system does. And the planets in almost all the known systems are packed in much closer to their stars than the worlds of the solar system – in part because close-in planets are the easiest to find. But the biggest difference between our system and all the others appears to be the lack of super-Earths and mini-Neptunes. A super-Earth is up to twice the diameter of Earth, and two to ten times Earth’s mass. Such worlds probably are dense and rocky. They may have thick atmospheres of hydrogen and helium, and perhaps deep oceans of liquid water. Mini-Neptunes are larger than super-Earths, but no bigger than Neptune. They probably have a solid core as well, but thicker layers of gases and liquids. The distinction between the two types of planets isn’t always clear. They probably have a lot in common – including the fact that we don’t have either of them in our own solar system. Script by Damond Benningfield

You might forgive Pollux if it feels disrespected. It’s the brightest star of Gemini – twice as bright as Castor, its “twin.” But the designation that’s most often used by astronomers is Beta Geminorum. And the Greek letter “Beta” usually is applied to a constellation’s runner-up. That naming system was created by German astronomer Johann Bayer, in 1603. He used the Greek alphabet to name most of the stars in a constellation. Usually, the brightest star was given the first letter, Alpha. The next-brightest was Beta, and so on. But in some cases, Bayer switched things up. He labeled the stars based on their location in the constellation’s classical outline, or on some other category. So for Gemini, Pollux became the “Beta” star even though it’s clearly brighter than “Alpha.” Pollux really is an impressive star. It’s moved into the red-giant phase of life. In fact, it’s the closest red giant to the Sun, at a distance of just 34 light-years. It’s puffed up to about nine times the diameter of the Sun, so it shines almost 40 times brighter than the Sun. And it has a distinctively orange tint – a beautiful look for an impressive star. Pollux and Castor line up to the upper left of the Moon at nightfall this evening. Pollux is closer to the Moon. The planet Jupiter is farther to the upper right of the Moon. Jupiter outshines all the true stars in the night sky – even the brightest light of Gemini. Script by Damond Benningfield