The bright Moon has some bright companions tonight: the planet Jupiter and the stars Aldebaran and Elnath. But the Moon washes out some fainter lights: the Leonid meteor shower.

The shower is expected to reach its peak late tonight – perhaps 15 or 20 meteors per hour. But only the brightest of them will shine through the glare of the just-past-full Moon.

The nearby planet and stars will be much easier to see – especially Jupiter, which will stand below the Moon as they climb into good view. It’s the brightest pinpoint of light in the sky for most of the night.

Jupiter is so bright for several reasons. For one, it’s the largest planet in the solar system – 11 times the diameter of Earth. For another, it’s blanketed by clouds that reflect most of the sunlight that strikes them. And finally, the planet is especially close now – less than 400 million miles away. It’ll be at its closest early next month.

Aldebaran is to the lower right of the Moon. It’s Taurus’s brightest star. It represents the bull’s eye. It shines bright orange, but the color might be muted by the nearby Moon.

Elnath is the second-brightest star of Taurus. It’s at the tip of one of the bull’s horns. It, too, is washed out by the moonlight. Even so, it should still be pretty easy to pick out – part of a beautiful arc around the gibbous Moon.

Jupiter and Elnath will be even closer to the Moon tomorrow night. More about that tomorrow.

Script by Damond Benningfield

The first intentional message to other civilizations was beamed into the galaxy 50 years ago tomorrow. There wasn’t much to it – just 1,679 bits of data. When properly decoded, the message yields a picture – stick-figure outlines of a person and the message’s planet of origin, for example. The image also features the facility that beamed it into space: the giant Arecibo radio telescope, which collapsed a few years ago.

The Arecibo message was conceived by Frank Drake. He was a pioneer in SETI – the search for extraterrestrial intelligence. He’d conducted the first search for radio signals just 15 years earlier. One of his collaborators was celebrity astronomer Carl Sagan.

The message was intended primarily as a publicity stunt. Arecibo had just received a major upgrade, and astronomers wanted to show it off. So the message was transmitted just once – it wasn’t repeated.

Other messages have followed, from radio telescopes around the world. Today, though, scientists and others are debating the wisdom of alerting the rest of the galaxy to our presence. They wonder whether messages to the stars might bring an unpleasant response.

The target for the Arecibo message was M13, a giant star cluster in Hercules. It’s in the west-northwest at nightfall, and it’s an easy target for binoculars or a small telescope. But it’s so far away that the message won’t get there for another 25,000 years.

Script by Damond Benningfield

Half of the planets discovered in other star systems are about the same size and mass as Uranus and Neptune, two of the giants of our own solar system. But we don’t know much about these exoplanets – in part because we don’t know much about Uranus and Neptune themselves. They’re billions of miles away, and only one mission has visited either planet.

But scientists hope to learn more around the middle of the century. A panel of scientists recommended a “flagship” mission to Uranus as NASA’s next big project for planetary exploration. An orbiter would loop around Uranus and its moons for years, while a probe would parachute into the planet’s atmosphere.

Uranus is an oddball. It lies on its side – probably the result of a collision with another planet when it was young. Scientists would like to know more about the impact and how it affected the planet’s interior. The sideways orientation also gives Uranus a cycle of seasons unlike that of any other planet. And some of the planet’s moons could have oceans of liquid water below their icy crusts.

NASA hasn’t yet started on the mission – in part because it’s working on a lot of other big-ticket items. So it’ll be a while before we get a close look at this common type of giant planet.

Right now, Uranus is low in the east as darkness falls. Tonight, it’s not too far to the lower left of the Moon. But it’s so faint that you need binoculars or a telescope to see it.

Script by Damond Benningfield

It’s cold in the outer solar system. The planet Uranus, for example, is 20 times farther from the Sun than Earth is. As a result, its 28 known moons all shiver at hundreds of degrees below zero. Yet several of the planet’s bigger moons might have active volcanoes. Instead of molten rock, they’d belch out molten ice – a slushy brew from buried oceans of liquid water.

We don’t know for sure if any of the moons have ice volcanoes, but there’s evidence that they do. The surfaces of the moons are fairly young, for example. That suggests that something is renewing them – like material from the interior. And a couple of the moons appear to be pumping material into the space around Uranus.

Recent observations by Webb Space Telescope found additional evidence for an ocean on the moon Ariel. It’s coated with frozen carbon dioxide. Webb found the layer of C-O-2 is especially thick. And it’s mixed with carbon monoxide. Both compounds should quickly vaporize and drift off into space. Their presence suggests the supply is being renewed – perhaps by volcanoes belching ice from a hidden ocean.

Uranus is putting in its best appearance of the year. The giant planet rises around sunset and is in view all night. It’s brightest for the year, too, although you still need binoculars to pick it out. Tonight, it lines up about half way between the almost-full Moon and the bright planet Jupiter.

We’ll have more about Uranus tomorrow.

Script by Damond Benningfield

Polar vortex has entered the American lexicon with a fury in recent years. It’s used to describe especially bitter outbreaks of winter weather. The northern hemisphere actually has two polar vortexes. The one that gives us the extreme cold is fairly low in the atmosphere. It’s formed by jet streams that encircle the pole that sometimes plunge southward. The other is much higher in the atmosphere.

The higher vortexes are seen on every planet and moon in the solar system with much of an atmosphere. That includes Uranus, the third-largest planet. Scientists found evidence to confirm the vortex last year.

Hints of a vortex around the north pole were seen in 2015. More recently, scientists looked at the pole with a giant radio telescope in New Mexico. They saw an especially bright area at the pole itself, with a dark ring around it. The bright region was warmer than the surrounding atmosphere. The combination provides strong evidence of a polar vortex.

Air in the upper atmosphere moves toward the poles. It’s deflected by the planet’s high-speed rotation – forming a “vortex” around the north pole.

Uranus is putting in its best appearance of the year. It’s lining up opposite the Sun, so it rises around sunset and is in view all night. It’s brightest for the year as well. But you still need binoculars or a telescope to see it, along the border between Taurus and Aries.

We’ll have more about Uranus tomorrow.

Script by Damond Benningfield

It’s springtime – on Mars, anyway – because today is the spring equinox for the Red Planet’s northern hemisphere.

Like the seasons on Earth, the seasons on Mars are the result of the planet’s tilt on its axis. In fact, the two planets are tilted at almost the same angle. So the north pole dips toward the Sun at the start of northern summer, while the south pole dips sunward at the start of northern winter. The equinoxes are half way between those points.

But there are some differences between the seasons on Earth and Mars. Mars’s orbit is more stretched out than Earth’s orbit, so there’s a bigger difference in the planet’s distance from the Sun. Mars’s distance varies by about 26 million miles.

That has a couple of effects. For one thing, it creates a big disparity between the seasons in the northern and southern hemispheres. Mars is farthest from the Sun during southern winter, and closest during summer. That means southern winters are colder than northern winters, while summers are warmer.

And second, Mars moves fastest when it’s close to the Sun, and slowest when it’s far away. That causes a big difference in the length of the seasons. Northern spring is the longest – it lasts 194 Mars days. Northern fall is the shortest – just 142 days.

Look for bright orange Mars climbing into good view in late evening, and high in the southwest at first light – a world that’s springing into a new season.

Script by Damond Benningfield

The Moon will stage a pair of cover-ups over the next couple of nights. The first happens tonight, when the Moon covers up the planet Saturn. And the second happens just 24 hours later, when it covers the planet Neptune.

The cover-ups are known as occultations. They occur because the Moon and planets all stay close to the ecliptic – the Sun’s path across the sky. But they all stray a few degrees to either side of the ecliptic. So most months, the alignment is off by a bit, so the Moon just misses the planets.

At times, though, the geometry is just right, as it is now – at least for parts of the world. Tonight, for example, the occultation of Saturn will be visible from a bit of South America, most of Central America, and the southern half of Florida. There, Saturn will disappear at about 9:20 p.m. It’ll remain out of sight for about 45 minutes. Because Saturn forms a tiny disk in our sky, it’ll take a few seconds for the planet to disappear and reappear – it won’t instantly blink off and back on.

The rest of the United States will see an especially close encounter between Saturn and the Moon. Saturn looks like a bright star, and will pass just a fraction of a degree from the Moon.

Tomorrow night, it’s Neptune’s turn. The path of the occultation will cross most of the United States. But Neptune is so faint that you need a telescope to watch the giant planet vanish – another cover-up for the gibbous Moon.

Script by Damond Benningfield

The bright Moon washes out the fainter stars tonight. One that shines through is Hamal, the leading light of Aries, the ram. It’s in the east at nightfall. It’s about 65 light-years away. And it’s a giant – bigger, heavier, and brighter than the Sun.

The other stars of Aries are tougher to see. And some stars that once formed separate constellations around it are impossible to see. In fact, they were tough to spot even when they were first outlined.

To the left of Hamal is Triangulum Minus, the little triangle. It was created by German astronomer Johannes Hevelius, in 1687. Its three stars are all quite faint. So even without the moonlight, they’re visible only under dark skies, away from city lights.

Below Hamal is Musca Borealis, the northern fly. It consists of four faint stars. The constellation was created by Petrus Plancius, in 1612. His original name for it was Apes, the bees. Later, another astronomer called it Vespa, the wasp. Hevelius then took over. He kept the buzzy theme, but he went with Musca, the fly. But there was already a fly in the southern hemisphere, so astronomers clarified matters by adding “northern” to the name.

In 1930, the International Astronomical Union adopted 88 official constellations, all with well-defined borders. The little triangle was incorporated into Triangulum. And the stars of the northern fly became part of Aries – buzzing around the rump of the ram.

Script by Damond Benningfield

Capella is a big mismatch. It’s a system of four stars, divided into two widely separated pairs. The members of one pair are both about two and a half times the mass of the Sun. But the members of the other pair are only about half the Sun’s mass. As a result, the two pairs face quite different futures.

Capella is the brightest star of Auriga, the charioteer, and the sixth-brightest star in the entire night sky. It climbs into good view in the northeast in early evening and soars high overhead during the night.

The system appears to be about 600 million years old – four billion years younger than the Sun. Yet the stars in the heavier pair are both at the end of life. They’ve burned through the original hydrogen fuel in their cores. That’s made them puff up to giant proportions.

Before long, both stars will shed their outer layers. The stars are close enough together that the expelled gas should act like a brake, causing the stars to spiral close together. But as the gas disperses, the stars will be much lighter. That will loosen their grip on each other, causing them to move farther apart. So no one is quite sure what the system’s final configuration will look like.

The smaller stars, on the other hand, will remain in the prime phase of life for tens of billions of years longer. But as the heavier stars trim down, the two pairs are likely to drift apart – splitting up a stellar quartet.

Script by Damond Benningfield

Scientists don’t have a crystal ball to help them foretell the future of the universe. But they can devise ideas about the future based on their understanding of the history of the universe and the laws of nature.

Based on that, perhaps the leading idea about the fate of the universe is the Big Freeze: The universe will get colder and darker, and eventually disintegrate into a soup of particles.

The key ingredient of the Big Freeze is dark energy. Scientists don’t yet understand its nature. But it causes the universe to expand faster as it ages. And if it keeps its foot on the accelerator, the universe faces a bleak future.

Hundreds of billions of years from now, the expansion rate will outpace the speed of light. Galaxies will disappear from each other – their light won’t move fast enough to reach most of the other galaxies.

The final stars will be born in a few trillion years. By then, most stars will have expired. Galaxies will consist mainly of the corpses of stars, plus some faint stars and smaller objects.

Over the eons, all the stars will die, and the stellar corpses will evaporate. And after trillions upon trillions of years, even black holes will vanish. Only ghostly particles will remain.

This future is far from certain. Scientists have many questions about dark energy and more. They’ll need to peer deeper into their crystal balls – the laws of nature – to tell us whether the universe will die in a Big Freeze.

Script by Damond Benningfield