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

If you head for orbit around Jupiter, you might want to take along your dust mop. Wide but thin rings encircle the planet. And they’re made of tiny particles of dust. Jupiter’s rings are nothing like the magnificent set that encircles Saturn. The rings are so faint, in fact, that they weren’t discovered until 1979, when the Voyager 1 spacecraft flew close to Jupiter. The system consists of four main rings. The inner ring, known as the halo, contains especially tiny particles, like a thin haze. The particles in the main ring are a little larger, but still quite small. And the two outer rings – known as gossamer rings – are wide and thick, but still don’t add up to much. The particles that make up the rings probably were chipped off of some the small moons that orbit close to Jupiter. Chunks of ice and rock slam into the moons, blasting out clouds of debris. The particles in the rings spiral into Jupiter quickly – within hundreds or thousands of years. So the rings are being constantly replenished by more impacts – adding to the dusty environment around the solar system’s largest planet. Jupiter teams up with the Moon and the twins of Gemini tonight. The planet looks like a brilliant star below the Moon at nightfall. It’s far brighter than any of the true stars. Gemini’s twins – the stars Castor and Pollux – line up to the lower left of the Moon. More about this beautiful grouping tomorrow. Script by Damond Benningfield