Stars are huge — anywhere from about 10 times the diameter of Earth to a hundred thousand times or more. Such a scale is just hard to fathom. One way to envision it is to consider how long it would take you to make one turn around such a giant body. An extreme example is Antares, the bright orange heart of Scorpius. It’s to the lower left of the Moon as they climb into good view tonight, after midnight, and about the same distance to the upper right of the Moon tomorrow night. Antares is a supergiant — one of the biggest stars in the galaxy. It’s also one of the brightest and heaviest. The exact numbers are a bit uncertain. In part, that’s because its outer layers are extremely thin — they just kind of taper off into space. And Antares is blobby instead of perfectly round. But a good estimate says it’s almost 600 million miles in diameter — about 75 thousand times wider than Earth. To get a better picture of that, imagine flying around Antares in a passenger jet at 600 miles per hour. At that speed, you could circle the Moon in about 11 hours, and Earth in about 40. And it would take six months to circumnavigate the Sun. For Antares, though, you’d need to pack a lot of movies on your mobile device. That’s because it would take 350 years to make one full turn around it — a whole bunch of frequent-flier miles for circling around a supergiant star. Script by Damond Benningfield

Over the millennia, stars acquire a lot of names. Some make sense, some don’t. And some of them might have gotten mixed up along the way. An example is the fourth-brightest star of Leo, the lion, which is about 58 light-years away. It represents the lion’s hip. A few centuries ago, it was assigned the name “Delta Leonis” — an indication of its ranking within the constellation. But it also has some older names, including Zosma and Duhr. Zosma comes from ancient Greek. It means “the girdle.” But that may be a mixed-up version of the original word, which meant “hip” or “back” — the star’s correct position in the lion’s anatomy. Duhr comes from ancient Arabic. It’s a shortened version of a phrase that means “the lion’s back.” Regardless of the name, Zosma is a pretty impressive star. It’s more than twice the size and mass of the Sun, and about 15 times brighter. And its surface is thousands of degrees hotter. Studies have shown that Zosma could be up to three-quarters of a billion years old. Stars of its mass burn through their nuclear fuel much faster than stars like the Sun. As a result, they live much shorter lives. Zosma should end its “prime-of-life” phase and head into old age in a few hundred million years. It’ll shine hundreds of times brighter than it does now — giving the lion a brilliant hip. Zosma is high in the sky at nightfall. It’s well to the right of Regulus, the lion’s brightest star. Script by Damond Benningfield

Immanuel Kant is best known for his ideas about philosophy, from ethics to the nature of knowledge. But he also played a role in the development of an idea about how planets are born. And while many of the details were off, his basic idea was sound. Kant was born 300 years ago this week, in the German state of Konigsberg. And during his 80 years, he never left it. He enrolled in the University of Konigsberg at age 16. But his father died, and he was forced to leave the university. He became a tutor for well-to-do families. He was able to return and finish his education in 1755. Kant was interested in just about everything — including science. Soon after completing his degree, he wrote about earthquakes, the weather, and more. One of his early works was “Universal Natural History and Theory of the Heavens.” In it, he described a “nebular” hypothesis for the formation of planets. A scientist in Sweden had conceived the idea a couple of decades earlier. Kant developed it further. He wrote that the Sun and planets were born from a nebula — a giant spinning cloud of gas and particles. Gravity caused the cloud to flatten, forming a disk. Material in the disk stuck together to make larger and larger chunks — eventually forming planets. Today, scientists have worked out more of the details. But the basic idea remains the same — Kant’s hypothesis provides a basic description of how planets are born. Script by Damond Benningfield

Few constellations have as many backstories as Virgo, the virgin. In ancient Greece and Rome, it was linked with several goddesses, each with her own story. In one story, she was Dike, the goddess of justice. She lived when the gods known as the Titans ruled the land. Everything was peaceful, it was always spring, and living was easy. But after Zeus and the Olympians defeated the Titans, life got much more complicated. The goddess had to work a lot harder to maintain peace. Eventually, things got so bad that she turned her back on humanity and settled among the stars. In another story, Virgo was Demeter, the goddess of agriculture and the harvest. The Sun entered that region of the sky in the fall, around the time of the harvest, strengthening the connection. Virgo’s brightest star is Spica — a name that means “an ear of grain.” It’s the only truly bright star around. It’s about 250 light-years away, and consists of two stars in a tight orbit around each other. The more massive of the two is likely to end its life as a supernova — a titanic blast fit for the early gods of ancient Greece. Spica stands just a whisker away from the full Moon tonight. They’re low in the southeast as twilight fades, separated by about half a degree — less than the width of a pencil held at arm’s length. They arc low across the south during the night, and set around dawn. Tomorrow: an early recipe for a system of planets. Script by Damond Benningfield

If you look straight up as the sky gets dark this evening, you won’t see much of anything. The region that’s high overhead is populated by some especially faint stars and constellations. But there’s a ring of brighter stars around it. The point directly overhead is called the zenith. And most of the time, unless you’re lying on a blanket and just watching the stars, you’re not likely to pay it much attention. It’s just too uncomfortable to tilt your head back that much. Instead, most of us look at what’s closer to eye level. Sometimes, it’s worth looking up there. Tonight really isn’t one of those times. The constellations near the zenith at nightfall include Leo Minor, the little lion; Lynx, a constellation so faint that you need the eyes of a cat to see it; and the part of Ursa Major that includes the feet and legs of the great bear, which are faint. And there’s an almost-full Moon in the sky, which overpowers dimmer stars. But if you look a little below the zenith, the view is more impressive. High in the south, for example, there’s Regulus, the bright heart of Leo, the big lion. And about the same height in the west, you’ll find Pollux and Castor, the “twin” stars of Gemini. Finally, in the northeast, you’ll find perhaps the most famous star pattern of all: the Big Dipper. Its stars outline the body and tail of Ursa Major. They’re the easy-to-spot parts of the great bear, standing high in the sky — just not at the zenith. Script by Damond Benningfield

The Little Dipper is famous for the star at the tip of its handle: Polaris, the North Star. Earth’s axis points in that direction, so all the other stars in the night sky appear to circle around it. The second-brightest star in the dipper is Kochab, at the lip of the bowl. It isn’t nearly as famous as Polaris, but it’s almost as bright. Kochab is a giant — more than 40 times the Sun’s diameter, and almost 400 times its brightness. It’s so big because it’s nearing the end of its life. The nuclear reactions deep inside the star push on the surrounding layers of gas, making them puff outward. Just when a star enters the giant phase of life depends on its mass. Heavier stars age much faster, so they “burn out” more quickly. And Kochab is more massive than the Sun. But just how massive has been the subject of debate. Studies using different techniques have yielded estimates of about 1.3 to 2.5 times the Sun’s mass. If Kochab had a companion star, it would be easy for scientists to measure the masses of both stars. For solitary stars like Kochab, though, astronomers rely on models of how stars behave. Today, the models seem to indicate a mass of about 2.2 times the Sun’s. But that isn’t completely settled. Until it is, we won’t know the complete story of Kochab. Kochab is moderately bright, and stands to the right of Polaris at nightfall. It rotates directly above the Pole Star in the wee hours of the morning. Script by Damond Benningfield

The Lyrid meteor shower is building toward its peak, on Sunday night. The Moon will be almost full then, so its glare will wash out all but the brightest of the “shooting stars.” The shower is the offspring of Comet Thatcher 1861. The comet orbits the Sun once every 415 years or so. As Thatcher approaches the Sun, some of the ice at its surface vaporizes. That releases small bits of dirt and rock into space. This debris spreads out along the comet’s path. Earth flies through this path every April. Some of the comet dust slams into our atmosphere and burns up — forming meteors. At least, most of it does. It’s likely that some of the grains fall to the surface. In fact, a recent study might have found some of those grains at the bottom of New York’s Hudson River. Researchers sifted through layers of sand and mud deposited thousands of years ago. The layers included fossils of microscopic organisms that were coated with tin — an element that likely came from outside Earth. The scientists also found other elements that probably originated outside our planet as well. The layers were laid down at roughly 400-year intervals — suggesting a possible connection with Comet Thatcher and the Lyrid meteors. The findings are preliminary. So we don’t know for sure whether there’s a link between the sediments at the bottom of the Hudson River and the streaks of light in April’s night skies. Script by Damond Benningfield

The Small Magellanic Cloud is a satellite galaxy of the Milky Way. It’s about 200,000 light-years away, it contains hundreds of millions of stars, and it’s easily visible to the eye alone — from the southern hemisphere. And it may actually consist of two separate but related halves — two galaxies for the price of one. Astronomers had suggested that possibility almost four decades ago. And a recent study provided the best evidence yet to support the idea. It found two large star-forming regions that are separated by about 15,000 light-years. One lines up in front of the other, making it hard to see them as individual objects. A team studied the galaxy in several ways. It found that gas and dust are split into two distinct regions. Their material moves in different ways, and has a different composition. The researchers also studied hot, young, bright stars. That also revealed two separate regions. And like the gas, the stars in the regions move in different ways, and have a slightly different makeup. The team said the two regions could be remnants of two galaxies that came together long ago. On the other hand, the region that’s closer to us could be the main body of the galaxy. The region behind it then could be a tail of stars and gas pulled out by the gravity of the nearby Large Magellanic Cloud, which is bigger and heavier. Either way, this close companion to the Milky Way may be more than meets the eye. Script by Damond Benningfield

The heart of the lion stays close to the Moon the next couple of nights. The bright star that marks the lion’s heart is Regulus. It’s to the lower left of the Moon at nightfall this evening, and to the upper right of the Moon tomorrow evening. Regulus is impressive. It’s a system of four stars, but only one shines bright enough to see. Known as Regulus A, it’s almost four times the Sun’s mass, and more than 300 times the Sun’s brightness. But the Moon is even closer to another star of Leo that’s more impressive. Eta Leonis is to the upper left of Regulus. It looks fainter than Regulus. Under the glare of the nearby Moon, in fact, it can be hard to see — especially from light-polluted cities. That’s only because Eta Leonis is much farther than Regulus — about 1800 light-years, versus only 79 light-years for Regulus. In fact, Eta Leonis is a one-percenter — among the biggest and brightest stars in the galaxy. Studies show that it’s about 10 times heavier than the Sun, about 50 times wider, and about 20 thousand times brighter. Eta Leonis is only about 25 million years old, compared to four and a half billion years for the Sun. But thanks to its great mass, the star is near the end of its life. Within a few million years, it’s likely to explode as a supernova. For a while, it will greatly outshine every other star in the galaxy — a brilliant beacon for the lion. Script by Damond Benningfield

Two giants of the solar system huddle close together in the evening twilight the next few days. The viewing window is short, so you need to time it just right to see them. Jupiter and Uranus are low in the west as twilight fades. Jupiter is easy to pick out — it looks like a brilliant star. Uranus is just above it tonight, by about the width of your finger held at arm’s length. But you need binoculars to pick it out. The planets will slide past each other on Sunday night. Uranus is the Sun’s third-largest planet — four times the diameter of Earth. Its atmosphere is topped by an organic “haze,” which makes it tough to see much below it. The atmosphere consists mainly of hydrogen and helium. These elements are left over from the planet’s formation, from the cloud of gas that enveloped the young Sun. The third-most-abundant member of the atmosphere is methane. It’s found mostly near the top of the atmosphere. Methane absorbs redder wavelengths of light, so Uranus looks like an almost featureless blue-green ball. Methane is at least partially responsible for the high-altitude haze. Methane itself makes up part of the haze. The ultraviolet light from the Sun breaks apart some of the methane molecules. Their carbon and hydrogen then combine in different ways to make ethane, acetylene, and other compounds. So the haze is like the smog found over major cities — blocking much of this giant planet from view. Script by Damond Benningfield