StarDate

Long before the fireworks blaze across the midnight sky, the solar system offers a lightshow of its own: an alignment of the Moon and two bright planets. But like an old Charlie Chaplin film, it’s completely silent — nature adds no pops, cracks, or whistles to the visuals.

Start looking not long after sunset, when twilight still bathes the sky in Technicolor hues — from oranges and reds close to the horizon to deep blues above.

The Moon perches quite low in the southwest at that hour, growing more prominent as the curtain of night drops toward the horizon. Sunlight illuminates only a small fraction of the lunar disk that faces our way, so it looks like a thin crescent.

As the sky grows darker, though, the dark part of the disk becomes visible as well. Even though it’s nighttime there, that portion of the Moon is bathed in earthshine — sunlight reflected off of Earth. It’s quite bright, so it makes the entire Moon stand out.

The next-brightest light pops into view not long after sunset, to the upper left of the Moon: the planet Venus — the brilliant “evening star.” It outshines everything else in the sky at that hour except the Moon.

And before long, the third night light brightens into view to the upper left of Venus: the planet Mars. It looks like a fairly bright orange star. And it’s the last of the three to vanish from view, setting around 10 o’clock — bringing this beautiful but quiet lightshow to an end.

Script by Damond Benningfield

No constellation is more brilliant than Orion the hunter, which is prominent in the evening skies of winter. Look for its three-star belt extending upward from the eastern horizon as night falls.

Part of Orion’s beauty comes from the bright star Betelgeuse, which is to the left of the belt in early evening. It’s one of the biggest stars in our part of the galaxy.

Some recent research indicates that Betelgeuse will blow itself to bits a lot sooner than most astronomers had thought.

You can tell that Betelgeuse is in trouble just by looking at it. Unlike Orion’s other bright stars, which are blue, Betelgeuse is orange. All of these stars were born big, bright, and blue. As a massive star ages, though, it expands, which causes its outer layers to get cooler and redder. So Betelgeuse's orange color, which is easily visible to the unaided eye, signals impending doom.

Betelgeuse will someday explode as a supernova. If it does so from its present distance of about 640 light-years, the explosion will rival the brightness of the Moon.

Astronomers have long thought the blast would occur within a million years. But new research suggests it’ll take place even sooner — within just the next hundred thousand years.

That still means that Betelgeuse is unlikely to explode during our lifetimes. But if the new work is correct, the star is closer to death than anyone had thought — and may treat our distant descendants to a real spectacle.

Script by Ken Croswell, Copyright 2016

Besides having a great name, Betelgeuse is one of the most impressive stars in the galaxy. It’s many times bigger and heavier than the Sun, and tens of thousands of times brighter. And it has an impressive fate: it will explode as a supernova; we’ll have more about that tomorrow.

But a recent study says it also has an impressive birth: The star was born with a cluster of other behemoths, many of which also will blast themselves to bits.

Researchers dug through the archives of a satellite that measured precise distances to more than a hundred thousand stars. From those observations, they made a 3-D map of the hottest, brightest stars within about 1600 light-years of Earth. The map revealed several streamers and clumps of these brilliant stars that hadn’t been noticed before.

One of those clumps stretches from Orion — the home of Betelgeuse — to nearby Taurus, so the researchers named it the “Taurion” association. Betelgeuse is near the edge of this clump, and it’s about the same distance as its other stars. Betelgeuse is also moving at the same speed and in the same direction as those stars. So the researchers suggested that the hunter’s bright shoulder was part of the same family — moving through the galaxy with some brilliant brothers and sisters.

Betelgeuse stands low in the east as night falls, and shines bright orange. The other stars of Orion stretch out to the right of Betelgeuse. The stars of Tau-rion stretch above it.

Script by Damond Benningfield

The deep freeze at the edge of the solar system is well stocked. Just this year, for example, astronomers discovered a new dwarf planet there, along with a moon for another dwarf planet.

This zone of cold and darkness begins with the Kuiper Belt — a thick ring that extends well beyond the realm of Neptune, the most distant of the Sun’s major planets. It probably contains tens of millions of chunks of ice and rock, all of which were left over from the birth of the planets. And still more of these icy leftovers orbit beyond the Kuiper Belt.

So far, astronomers have actually seen only a couple of thousand objects in or beyond the Kuiper Belt. But several of them are big enough to classify as dwarf planets — including the most famous of them all, Pluto.

Earlier this year, a team using a telescope in Hawaii announced the discovery of a new dwarf planet. RR245 is probably about 400 miles in diameter. It follows a stretched out orbit that carries it more than 100 times farther from the Sun than Earth is. Right now, it’s moving toward the Sun, and will reach its closest point in about 80 years.

Also this year, another team used Hubble Space Telescope to discover a moon orbiting the dwarf planet Makemake, which is well beyond the orbit of Pluto. The moon is probably less than a hundred miles in diameter — roughly a tenth the diameter of Makemake.

These discoveries show that there’s still a lot to find in the deep freeze of the outer solar system.

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Pluto’s biggest moon is the fashion plate of the outer solar system: It’s topped by a red “beanie cap” — a possible gift from Pluto.

Charon is roughly 750 miles in diameter — about half the size of Pluto itself. The New Horizons spacecraft, which flew past Charon last year, found that its surface is marred by long, deep cracks. They may have formed when an underground ocean of water froze and expanded, fracturing the layers of ice above it.

New Horizons also found that the region around Charon’s north pole is darker and redder than the surrounding landscape. And a recent study proposed one possible explanation: it’s contaminated by material from Pluto.

Pluto’s surface consists mainly of frozen nitrogen and methane. Some of these ices vaporize, and a tiny fraction of them eventually escape into space. Charon sweeps up a bit of this material, which settles at the poles — especially at the winter pole, where it’s dark and cold.

When the winter pole emerges into daylight, sunlight creates chemical reactions that convert some of the nitrogen and methane to tholins — organic compounds that look orange or red. Most of the remaining nitrogen and methane ices then vaporize, leaving a thin layer of tholins.

New Horizons saw the red cap at Charon’s north pole, where it’s summer. But there are hints that the south pole, which is cloaked in the darkness of winter, is also topped by tholins — compounds that may give Charon two red beanie caps.

Script by Damond Benningfield

The most prominent feature on Pluto is like a cold lava lamp, with big blobs of ice slowly bubbling to the surface.

Sputnik Planum looks like a white heart. It’s bigger than Texas and Oklahoma combined, and it’s filled with frozen nitrogen. The ice looks like it’s pieced together like the tiles on a floor, with each tile anywhere from about 10 miles to 30 miles wide.

Researchers used computer simulations to try to decipher why the feature looks that way. They concluded that Sputnik Planum is a big impact crater filled with a layer of frozen nitrogen that’s several miles thick. And none of that ice appears to be more than about a million years old.

Ice at the bottom of the ice layer is warmed by the faint heat of Pluto’s interior. Big blobs of the warmer ice rise through the cooler ice above — at a rate of an inch or two a year. So it takes half a million years or so for a given blob to reach the surface. At the surface, the blob cools and drops back into the icy depths — keeping Pluto’s “lava lamp” going.

Other simulations have found something even more remarkable: A global ocean of liquid water appears to lie beneath Pluto’s icy crust. A study found that the ocean could be dozens of miles deep, and as salty as the Dead Sea here on Earth. Some of the water could occasionally bubble up through cracks in the crust, creating fresh ice on Pluto’s frigid surface.

We’ll talk about a “beanie cap” of ice on Pluto’s largest moon tomorrow.

Script by Damond Benningfield

Some beautiful decorations light up the evening sky on this Christmas night. Venus, the brilliant “evening star,” is low in the southwest as night falls. Mars stands to the upper left of Venus, shining pale orange. And the Summer Triangle perches low to the right of the two planets, with its highest point marked by Deneb, the star at the tail of Cygnus, the swan.

When the swan stands high in the sky, it really does look like a graceful bird soaring through the starry Milky Way. As it noses toward the horizon, though, the pattern looks more like its other name: the Northern Cross. It’s just above the horizon around 8 or 9 o’clock, with the long axis standing straight up, and the cross parallel to the horizon.

Cygnus was first drawn thousands of years ago. But if the people who created it could look at the stars tonight, they wouldn’t notice any difference in its pattern at all.

The stars are all moving around the center of the galaxy at a good clip. And they’re at different distances from Earth, so their motions across the sky are different, too. So over time, the familiar patterns in the night sky will become distorted — and, eventually, unrecognizable. But on the human scale, “eventually” is a long time. The stars are all so far away that their drift across the sky is imperceptible — even over the span of many lifetimes.

So the graceful swan — and the Northern Cross — will continue to decorate the night sky for millennia to come.

Script by Damond Benningfield

After the family dinner is nothing but a pile of dishes the next couple of nights, and the presents have all been unwrapped, you might step outside for a bit to enjoy one more Christmas treat: the glorious night sky. With winter upon us, you’ll see some of the most beautiful of all the stars and constellations.

About 9 o’clock, for example, look in the southeast for Orion, perhaps the shiniest constellation of all. First, find its three-star belt, which aims straight up and down. It’s flanked by the bright orange star Betelgeuse on the left, and the bright blue star Rigel on the right.

If you have a dark sky, look to the lower right of the belt for Orion’s sword. It consists of a couple of stars, plus a fuzzy patch of light in the middle of the sword. That’s the Orion Nebula — a massive cloud of gas and dust that’s giving birth to new stars. Thousands have already been born, and many others are taking shape even now.

Below Orion, just above the horizon, look for dazzling Sirius, the brightest star in the night sky. It twinkles fiercely, quickly changing from red to blue to pure white.

About the same distance above Orion you’ll come to Taurus, the bull. It’s best known for its bright orange eye, the star Aldebaran, which stands at one point of the bull’s V-shaped face. And the bull’s shoulder, above Aldebaran, is marked by the tiny dipper-shaped star cluster known as the Pleiades — one of the many beautiful sights in the holiday sky.

Script by Damond Benningfield

Winter is just getting cranked up here in the northern hemisphere, but you can already find a hint of spring in the air — in the pre-dawn sky. The stars and constellations that are in view a couple of hours before sunrise right now are the same ones that’ll be in view a couple of hours after sunset in late April.

Look high in the east, for example, for yellow Arcturus, one of the brightest stars in the night sky. Low in the northeast, you’ll find slightly fainter Vega, the top point of the Summer Triangle. And between Vega and Arcturus, look for Hercules. It’s marked by an off-kilter “square” of stars known as the Keystone.

Over in the west, the twins of Gemini stand upright. The stars that mark their heads, Pollux and Castor, remind some skywatchers of a pair of eyes. And two bright stars flank the constellation: Procyon to the left and Capella farther to the right.

All of these stars rise and set about four minutes earlier each night. So in four months, the stars that are now in the east before dawn will be rising eight hours earlier. With the change in the time of sunrise and sunset, that means they’ll be in good view after dusk — ready to put on a good show all night.

And the stars that are now in the west before dawn will disappear before midnight in April — getting ready to reappear in the morning sky not long afte, continuing the cycle of stars through the seasons.

We’ll talk about the current evening sky tomorrow.

Script by Damond Benningfield

Many of the stars in our galaxy have stellar companions — they’re gravitationally bound to one or more other stars. But just how many stars have companions is poorly understood. One study says about a third of the stars in the Milky Way are members of systems with at least two stars, while other studies say it could be half or more.

Something else that’s uncertain about these systems is how they form. There are a couple of leading ideas, and it’s possible that both of them are right.

All stars are born from the collapse of a giant cloud of gas and dust. As the cloud contracts, a dense clump forms in the middle, with a spinning disk around it. The clump forms the star, while the disk may give birth to planets.

But as the cloud collapses, turbulence may cause it to form more than one clump. Each clump then coalesces to form a star. That may be the best idea for systems where there’s some space between the stars.

A second idea says that as a star is taking shape, a second disk of material forms within the original disk. The second disk then collapses to create a second star that’s quite close to the first one.

One binary where the two stars are especially close is Spica, the leading light of Virgo. It stands to the right of the Moon at first light tomorrow. The bright planet Jupiter is above Spica. The Spica system consists of two massive, brilliant stars in a very tight orbit — stellar companions whirling through the Milky Way.

Script by Damond Benningfield