Today, Saturn and its system of moons and rings look calm and peaceful. But things might have been much more chaotic in the fairly recent past. A collision between two moons might have destroyed one of them, changed the orbit of the other, and led to the birth of yet another moon and the planet’s rings. Researchers have been trying to explain some oddities in the Saturn system. The planet itself is tilted far more than it should be, for example. The biggest moon, Titan, follows a more lopsided orbit than expected. And the moon is moving away from Saturn by about four inches per year. A few years ago, a team proposed that Saturn once had another big moon, which the team called Chrysalis. Interactions between the moons might have kicked Chrysalis so close to Saturn that it was ripped apart, forming the rings. But this year, another team came up with a slightly different scenario. It, too, involves a second moon. It collided with Titan a few hundred million years ago, changing Titan’s orbit. Debris from the impact formed the present-day moon Hyperion. The activity caused two other moons to ram together as well. Both moons quickly re-formed, with the leftovers spreading out to form the rings as recently as 50 million years ago. This model explains many of the system’s oddities – bringing order to a chaotic arrangement. Look for Saturn near our moon at dawn tomorrow. The planet looks like a bright star, low above the horizon. Script by Damond Benningfield

Venus might be feeling a bit neglected. The last dedicated mission to the planet wrapped up its work two years ago. A couple of spacecraft have scanned the planet since then, but Venus wasn’t their main target. They were using the planet’s gravity to fling them toward their intended targets. But Venus exploration could tick up over the next few years. Several missions are being developed. Most of them are big and complicated, so they won’t be ready until the next decade. But a craft the size of a beachball could head for Venus as early as this summer. It’ll probe the planet’s clouds for signs of organic compounds – the chemistry of life. Venus Life Finder is a project of Rocket Lab and MIT – the first commercially developed mission to the planet. It’s a small, blunt cone. When it arrives at Venus, it will plunge through the planet’s clouds, shining a laser on the way down. The reflected light will reveal details about the cloud particles. Bits of organic matter might be set aglow. Some recent observations have hinted that the clouds could contain microscopic life. Life Finder won’t actually search for life, but it could tell us if the building blocks of life lurk inside the planet’s clouds. Venus is the “evening star.” It’s sneaking up on the star Elnath, at the tip of one of the horns of the bull. Tonight, the star is a little to the upper right of Venus. The planet will slip past it during the week. Script by Damond Benningfield

The eyes of the dragon shine a third of the way up the northeastern sky at nightfall. Eltanin is the brightest star of Draco, with third-ranked Rastaban just above it. They circle high across the north during the night, and stand in the northwest at first light. Although Eltanin looks brighter than Rastaban, that’s only because of their different distances. Eltanin is about 150 light-years away, while Rastaban is at 380 light-years. So if you lined them up side by side, Rastaban would shine about twice as bright as the dragon’s other eye. Rastaban is only about 65 million years old, compared to four and a half billion years for the Sun. Yet it’s already passed the end of its “prime” lifetime. That’s because it’s about six times as heavy as the Sun. Such massive stars “burn” through their nuclear fuel at a frantic rate. So Rastaban has already converted the hydrogen in its core to helium. Now, it’s probably getting ready to ignite the helium to make carbon and oxygen. That’s caused the star to puff up – it’s about 40 times the diameter of the Sun. That’s the main reason it looks so bright – there’s a lot of surface area to beam light out into space. Eventually, the nuclear reactions in the core will stop. The star’s outer layers will blow out into space. That will leave only the dead core – a cosmic ember as heavy as the Sun but only as big as Earth – closing one of the dragon’s bright eyes. Script by Damond Benningfield

A pair of eyes stares down from the northeast as night falls now – the eyes of Draco, the dragon. They’re to the upper left of brilliant Vega, one of the night sky’s most prominent stars. The brighter eye is the star Eltanin, the dragon’s leading light. The name means “the serpent,” because the star once represented the entire dragon. Eltanin is an orange giant. It’s a good bit bigger, heavier, and brighter than the Sun. That makes it easy to see even though it’s more than 150 light-years away. The star should get a lot easier to see in the coming millennia. That’s because Eltanin and the Sun are moving closer together. In about one and a half million years, they’ll be at their closest – just 28 light-years apart. Assuming Eltanin hasn’t changed much by then, it’ll be the brightest star in the night sky – about as bright as the current champ, Sirius. The other eye, Rastaban, is just above Eltanin. Its name means “head of the serpent.” It’s more than twice as far as Eltanin. It, too, is a giant, but it’s much bigger and brighter – a thousand times as bright as the Sun. So it looks only a little fainter than Eltanin despite the extra distance. The rest of Draco curves to the left and above the dragon’s eyes, and curls around Polaris, the North Star. The eyes stare in the opposite direction – toward Hercules, who killed the dragon before both of them were placed in the heavens. Script by Damond Benningfield

Last July, space telescopes recorded an event that sounds like the plot of a “B” horror movie: Zombie Versus Vampire. Spoiler alert: the vampire won. It drained away the zombie’s life’s blood – or make that its after-life’s blood. The encounter took place in a galaxy billions of light-years from Earth. Space telescopes detected a sudden flare-up in X-rays from the galaxy’s outskirts. The region also produced several short outbursts of gamma rays, the most powerful form of energy. At their peak, each burst produced as much energy every second as the Sun will emit in a billion years. Analysis revealed a possible explanation: a medium-sized black hole devoured a white dwarf – the “corpse” of a Sun-like star. Astronomers have seen similar encounters before. But most of them involved stars that were in the prime of life, so the stars were big. A white dwarf is only about as big as Earth, which is just one percent the Sun’s diameter. So a white dwarf is compact and extremely dense. Its surface gravity is strong, so it’s not easily disrupted. In this case, though, the white dwarf buzzed a black hole about 75,000 times the mass of the Sun. The black hole’s gravity ripped apart the white dwarf in one big bite. Debris swirled around the black hole. Magnetic fields fired some of it into space at almost the speed of light, creating bursts of gamma rays. The whole thing was over in a flash – as the vampire sucked the zombie dry. Script by Damond Benningfield

A massive star in the Andromeda Galaxy might have tried to blow itself to bits, but it failed. Instead, almost the entire star collapsed to form a black hole about five times the mass of the Sun. Astronomers discovered the possible misfire while combing through observations by NeoWise, a space telescope that wrapped up its work a couple of years ago. They found an object that brightened dramatically at infrared wavelengths, which are invisible to the human eye, then slowly faded again. Earlier observations at visible wavelengths showed a supergiant star, perhaps a hundred thousand times as bright as the Sun. But as the infrared peaked and faded, the visible light faded completely – the star simply vanished. The astronomers concluded that the event was a failed supernova. The star stopped producing nuclear reactions in its core, so the core collapsed. A shockwave plowed through the star’s outer layers, blasting their gas outward. In most cases, such a shockwave creates a titanic explosion – a supernova. But this blast wasn’t powerful enough to overcome the core’s gravitational pull. So almost all the gas fell back onto the core, making it massive enough to form a black hole. A little material did escape. It formed a wide disk of gas and dust around the dying star. Energy from the star made it shine brightly in the infrared – a short flare-up that waned as the supergiant star collapsed and faded from sight. Script by Damond Benningfield

More than 1.1 billion years ago, a pair of black holes staged a violent merger. As they spiraled inward, the black holes produced an outburst of gravitational waves – “ripples” in spacetime that rang across the universe. Detectors on Earth “heard” those ripples in January of last year. In fact, it was the loudest and clearest detection of merging black holes to date. Analyzing the signal has told scientists quite a bit about black holes, and about the laws of gravity that govern them. The frequency and duration of the gravitational waves revealed details about the black holes. It showed that when they merged, each of them was spinning. And each was about 33 times the mass of the Sun. But the total mass after they merged was only about 62 times the Sun’s mass – less than the combined weight of the individual black holes. The rest of their mass was converted to energy – mainly the gravitational waves. The aftermath of the merger was important as well. The merged black hole vibrated like a ringing bell. As it settled down, the “ringing” faded away. How it faded matched predictions made by General Relativity – the theory of gravity introduced by Albert Einstein and refined by many others over the decades. It was the strongest evidence to date that General Relativity really is the rule that governs black holes – and sends gravitational waves rippling across the universe. Script by Damond Benningfield

For a trip that’s out of this universe, just cross the event horizon of a black hole. Nothing that passes through an event horizon can ever come back out, so we don’t really know what goes on inside a black hole. But we can be pretty sure that it’s like nothing else in the universe. A black hole’s mass is concentrated in a single point, called a singularity. Its gravity is infinitely strong. But as the distance from the singularity increases, its grip weakens. Eventually, it reaches a point where the escape velocity equals the speed of light – the event horizon. Since nothing can travel faster than light, anything that falls through the horizon is trapped. It may be doomed to merge with the singularity. So the event horizon acts like the “surface” of a black hole. But it’s not solid – there’s nothing to ram into. Instead, it’s more of a boundary between the black hole and anything outside it. The distance between the singularity and the event horizon marks the size of the black hole. And as more stuff falls in, the black hole gets bigger. A black hole that’s 10 times the mass of the Sun spans about 35 miles. The supermassive black hole at the heart of the Milky Way spans 13 million miles. And the heaviest black holes yet seen are more than 40 times the size of the orbit of Neptune, the Sun’s outermost major planet – a wide entrance to an out-of-this-universe experience. More about black holes tomorrow. Script by Damond Benningfield

Comet Halley’s loss is Earth’s gain. As the comet orbits the Sun, it sheds a bit of ice and dirt from its surface. That debris spreads out along the comet’s path. Earth passes close to that path twice a year. Some of the solid particles ram into our planet, adding a minuscule amount to Earth’s mass. For skywatchers, the intersection creates two meteor showers, as the comet dust vaporizes in the atmosphere. And one of them is under way now: the Eta Aquariids. The shower’s peak lasts for several nights, centered around tomorrow night. At its best, the shower can produce a few dozen meteors per hour. Halley is a chunk of rock and ice about seven miles in diameter. On average, it orbits the Sun once every 76 years, although that period varies by a few years. It’s been recorded in Earth’s night sky for more than 2,000 years. Edmond Halley linked some of those appearances in 1705, demonstrating that a comet can return to view multiple times. Halley also predicted the comet’s next appearance, in 1758. When it showed up at the time he forecast, the comet was named in Halley’s honor. Over the centuries, the comet’s orbit moves away from Earth a bit. Today, we’re several million miles from that path. As the orbit shifts away, we pick up less and less of the comet dust. That makes the meteor showers less impressive. So over time, the Eta Aquariids will slowly die out. Script by Damond Benningfield

Antares has played a big role in the skylore of many cultures. And it’s not hard to understand why. It’s quite bright, it has a fiery orange color, and it’s near the ecliptic – the Sun’s path across the sky. The Moon and planets are close to the ecliptic as well, so they periodically swing past Antares. In fact, the Moon snuggles quite close to it late tonight. In western skylore, Antares represented the heart of Scorpius, the scorpion. After Orion the hunter bragged that he could kill any beastie on Earth, the angry gods sent the scorpion to sting him to death. They then put Orion and the scorpion on opposite sides of the heavens, so one rises as the other sets. Antares and the surrounding stars also represented a scorpion in the mythology of the Maya and several other cultures. But others saw Antares differently. In China, it was the “fire star” – a description of its color. It and a couple of nearby stars represented the heart of a dragon. And in Hawaii, Antares was part of a fishhook used by the god Maui. The star itself is worthy of its reputation. It’s a dozen or more times heavier than the Sun, hundreds of times wider, and tens of thousands of times brighter – a supergiant star with some supergiant stories. Antares is just a skosh away from the Moon as they climb into good view tonight, by midnight. They’ll still be close as dawn twilight erases the scorpion’s mighty heart from view. Script by Damond Benningfield