StarDate

Gold and silver are beautiful, but they’re also rare — they account for only a few parts per billion of Earth’s crust.

These and other heavy elements, such as uranium and platinum, are so rare because they’re hard to make. They contain many protons and neutrons, and it’s hard to create the conditions needed to make all those particles stick together.

Some of these elements may be formed in the titanic explosions known as supernovae. But it takes the right kind of explosion to make these heavy elements. Such blasts don’t appear to be common enough to supply all of these elements that are seen in the universe.

So scientists have looked for other possible birthplaces. One possibility is the merger of two neutron stars — the dense, heavy cores of exploded stars. The merger spins off matter, which could stick together to form gold and other heavy elements.

A recent study proposed an even more exotic possibility: a small black hole eating a neutron star. The idea says that small black holes were created shortly after the Big Bang. Occasionally, one of them rams into a neutron star and settles in the star’s core.

As the black hole devours the surrounding material, the neutron star spins faster. Eventually, it may spin fast enough to sling material from its surface out into space. Some of the material could then stick together to form the nuclei of gold, silver, and other heavy elements: cosmic creation from a cosmic death.

Script by Damond Benningfield

 

The bull will get an eye patch tonight. As seen from the eastern U.S., the Moon will pass in front of Aldebaran, the eye of Taurus, hiding the star from view. Aldebaran will stand close to the Moon as night falls. The Moon will then close in on the bright star and pass in front of it.

What’s happening inside Aldebaran is always hidden from view. From the star’s size and brightness, though, astronomers have a good idea of what’s going on. Aldebaran has converted the hydrogen fuel in its core to helium. Now, it’s either converting the helium to carbon and oxygen, or it’s just about to.

In fact, that’s how all the carbon and oxygen in the universe were made — in the hearts of stars.

The Big Bang created huge amounts of hydrogen and helium and a tiny smattering of a couple of other elements. But conditions weren’t right for making heavier elements. Conditions are right in the cores of stars, though.

After it’s burned through the hydrogen to make helium, the core shrinks and gets hotter. That creates the conditions necessary for the nuclei of helium atoms to stick together to make carbon and oxygen.

In stars like Aldebaran and the Sun, the process stops there. But in heavier stars, temperatures in the core get even hotter. That allows the stars to make even heavier elements — all the way up to iron. Most of the elements beyond iron are made either in stellar explosions or in even more-exotic environments — acts of alchemy in the stars.

Script by Damond Benningfield

Many Americans have never really seen the night sky. They get a good view of the Moon, the planets, and a few bright stars. But they can’t see the full star patterns that outline the constellations, or the faint sparks known as meteors. And they don’t have a chance of seeing the subtle yet awesome band of the Milky Way — the combined glow of millions of individual stars.

That’s because most Americans live under a blanket of light pollution. The lights that illuminate streets, businesses, sports arenas, and even our own back yards cast a glow into the sky. This light bounces off dust grains, as well as the molecules of gas that make up the atmosphere, filling the sky with light. So the bigger and brighter the city, the murkier the skies.

And at times, a big natural light source blots out many of the subtleties of the night sky as well: the Moon. That’s especially true on nights like tonight. The Moon is just past full as it rises this evening, so it’s a big spotlight that’s in the sky all night. Even from locations far from city lights, the brilliant Moon can still overpower much of the view.

So on nights with a bright Moon, even those with otherwise dark skies have a limited menu of items to look for in the sky. Tonight, one of the stars that shines through is Capella, the leading light of Auriga, the charioteer. It’s off to the left or upper left of the Moon in early evening — a star that shines through the glow of a moonlit night.

Script by Damond Benningfield

 

For the first 85 years after its discovery, Pluto was a faceless world — an iceball too far away for us to see any of its features. The New Horizons spacecraft filled in those features when it flew past Pluto in 2015. It found mountains, ridges, and vast expanses of ice. And now, 11 of those features have names.

The names were bestowed by a committee of the International Astronomical Union. It adopted several names that were suggested by the New Horizons team. It also selected names recommended by members of the public in a contest.

The largest feature on Pluto is a heart-shaped region made of ice. The New Horizons team named it after Clyde Tombaugh, who discovered Pluto, and the IAU accepted the name.

The brighter half of that feature was named the Sputnik Plains in honor of the first Earth-orbiting satellite, Sputnik 1, which was launched 60 years ago.

Two mountain ranges at the edge of that plain were named for Sir Edmund Hillary and Tenzig Norgay, the first men to climb Mount Everest and return safely.

Other features were named for characters and locations from the mythologies of several cultures, and for other missions of discovery. And a crater was named for Venetia Burney, the schoolgirl who suggested the name “Pluto” for the newly discovered world.

Many other features revealed in the New Horizons pictures are still to be named. When they are named, mapmakers can begin to fill in the details of this once-faceless world.

Script by Damond Benningfield

 

A century ago, many astronomers thought the entire universe was confined to our home galaxy, the Milky Way. And none of them knew that the universe was expanding. But a telescope that took its first look at the sky 100 years ago today changed that.

The 100-inch telescope at Mount Wilson Observatory was the brainchild of George Ellery Hale. He’d already headed development of two other giant telescopes, but he wanted more. The bigger the telescope, the more light it gathers, allowing it to see objects that are fainter and farther away — opening up more of the universe to our curious eyes.

Building the telescope wasn’t easy. Crews used mule teams to lug the telescope and its dome up treacherous mountain trails. But when it was finished, it was the largest telescope in the world — a distinction it held for three decades.

One of the astronomers who used the new telescope was Edwin Hubble, for whom Hubble Space Telescope is named. He looked at a special type of star in the Andromeda Galaxy. These stars are good signposts for measuring astronomical distances. Hubble found that Andromeda was far, far outside the Milky Way — an “island universe” of billions of stars.

And measurements of the motions of Andromeda and other galaxies revealed that the universe itself is expanding — a discovery that helped lead to the idea of the Big Bang. So the hundred-inch telescope greatly expanded the universe — and our understanding of its birth.

Script by Damond Benningfield

The star Gliese 710 is so faint that it’s invisible to the eye alone. In 1.3 million years, though, it’ll be the brightest star in the night sky, as it passes about a quarter of a light-year away.

The encounter could be deadly: The star could deflect some of the icy bodies that surround the Sun, sending them toward the inner solar system, where they could smack into Earth.

Researchers reached that conclusion when they combined older data with the first 14 months of observations by Gaia, a European satellite that’s plotting the distances to a billion stars in the Milky Way galaxy. The study found that Gliese 710’s encounter will be roughly one-third the distance of previous estimates — the closest of any star in the next five million years.

During that span, up to 600 stars will pass within 16 light-years of Earth, with up to two dozen passing within three light-years. The gravity of any of these stars could stir up the Oort Cloud, a shell of icy bodies that forms the outer edge of the solar system. When such bodies enter the inner solar system they form comets, with long, glowing tails. If a comet strikes Earth it can decimate life. In fact, that probably happened about 65 million years ago, when an impact by a comet or asteroid helped bring about the demise of the dinosaurs.

More observations by Gaia should allow astronomers to refine the new estimates, and extend the projections of encounters to 25 million years into the future.

Script by Damond Benningfield

A “spooky” star is one of the highlights of the Halloween sky. The star is in Perseus, the hero, which is in the east as night falls. It consists of three stars. As seen from Earth, two of the stars periodically eclipse each other. So every three days or so, the system gets much fainter. Ancient skywatchers found this a bit frightening, so they named the star Ra’s Al-Ghul — the head of the ghoul. Today, it’s known by a shorter version of the name: Algol, the Demon Star.

The U.S. Navy liked that name so much that it bestowed it on a class of cargo ships. All the members of the class are named for bright stars, including Antares, Capella, and Algol itself.

Star names have been popular in many settings. The names convey beauty, power, and perhaps a bit of mystery. So cars have been named for Vega and the constellation Taurus, among others. Many airliners have borne star names as well, including Hokule’a and Nahiku — Hawaiian names for the star Arcturus and the Big Dipper. And characters in the Harry Potter universe are named for Sirius, Bellatrix, and other stars.

The navy has used many star names, mainly during or after World War II. The names have been bestowed on cargo ships, submarine tenders, and other support craft, as well as research vessels.

Other ships have been named for constellations, with still others named for star patterns that aren’t constellations, such as the Hyades star cluster — bits of the night sky on the high seas.

Script by Damond Benningfield

In Greek mythology, Perseus was a hero — he rescued the princess Andromeda from a nasty sea monster. And the brightest star of the constellation that depicts Perseus befits a hero: It’s big, heavy, and bright.

Mirfak is far more impressive than the Sun: seven or eight times heavier, about 60 times wider, and about 5,000 times brighter. That makes it easy to see even though it’s more than 500 light-years away.

Yet there’s more to Mirfak than meets the eye — perhaps including a companion star.

Mirfak produces a lot of X-rays. That’s a bit of a surprise for a star of its temperature and stage of life. That could mean that Mirfak is an oddball — that some unknown mechanism is causing it to produce the X-rays. But it also could mean that it has an unseen companion — a smaller star with a hot outer atmosphere, like the Sun’s corona.

Searches for such a star have turned up empty — so far. But the system is so far away, and Mirfak itself is so bright, that a companion easily could be hidden in Mirfak’s glare. If such a star exists, it would only add to the impressiveness of the hero’s leading light.

And that light is in the northeast as darkness falls, above the brighter star Capella. Mirfak is an easy target even from light-polluted cities. Most of the constellation’s other stars stream away to its right and lower right. That includes the hero’s second-brightest star — the “demon” star. We’ll have more about that tomorrow.

Script by Damond Benningfield

The Moon is sailing across the “celestial sea” — a group of constellations that are related to water. And it’s a lengthy cruise: The Moon won’t climb out of the sea until Friday.

Most of the sea is in view at nightfall. And by about 11 o’clock, it will span the entire southern sky. It incorporates the sea-goat, the water bearer, the fishes, the southern fish, the sea monster, and the celestial river.

These constellations were associated with water for a couple of reasons. First, they inhabit a relatively dark region of the sky, with only one bright star — Fomalhaut, the mouth of the southern fish. And second, they appeared in the sky during the rainy season in the eastern Mediterranean, where the constellations were drawn and their stories written.

Tonight, the Moon is just passing into the edge of Aquarius, the water bearer. Although it’s perhaps the most famous member of the sea, it’s not much to look at. It depicts a man or boy carrying a jug of water, which is pouring toward Fomalhaut.

That picture appears to trace back to ancient Babylon. The stars represented one of the most important gods, who was shown as a man carrying an urn filled with water. And in ancient Egypt, the stars were associated with the annual flooding of the Nile River.

The Moon will sail across Aquarius and Pisces over the next few nights, flanked by some of the other watery contellations. It won’t stand against the stars of a more earthy constellation until Friday.

Script by Damond Benningfield

A beautiful Moon slides across the southwestern sky this evening. It’s a day past first quarter, so the Sun illuminates about half of the lunar hemisphere that faces our way. The Moon sets by around 1 or 2 a.m.

Many groups across the country and around the world will be keeping an especially close watch on the Moon tonight. That’s because it’s Observe the Moon Night — an event created by NASA almost a decade ago to promote its Moon exploration program. The event has caught on. Hundreds of museums, schools, planetariums, and other science-related groups host events, in the United States and dozens of other countries.

The event is timed so that the angle of the Sun makes it easier to make out features on the lunar surface. A lower Sun angle creates longer shadows, so mountains, canyons, and craters really stand out when you see them through a telescope.

You can make out several dark volcanic “seas” on the Moon with your eyes alone. Near the limb of the illuminated portion of the lunar disk, look for a small, round feature known as the Sea of Crises. Nearby, there’s a bigger sea — the Sea of Tranquility, where astronauts first landed on the Moon, back in 1969. And down at the bottom of the Moon, see if you can make out a large crater with streaks radiating away from it — the crater Tycho.

These and many other prominent features make the Moon a beautiful sight — not just tonight, but all year long.

Tomorrow: Sailing the celestial “sea.”

Script by Damond Benningfield