StarDate

On the evening of January 12th of 1820, 14 “gentleman astronomers” met over dinner at Freemason’s Tavern in London. By the time the last brandy was quaffed, they’d established a society for studying and promoting astronomy. Today, it’s one of the leading astronomy groups in the world: the Royal Astronomical Society.

It was founded as the Astronomical Society of London. It gained a royal charter from King William IV a few years later.

From the beginning, it held regular meetings to allow its members to keep up on the latest findings, and to share ideas. Today, the society holds an annual conference that’s one of the world’s largest astronomy meetings.

In 1827, it established its first journal — the “Monthly Notices.” It's still published today. And in the 1800s and early 1900s, it helped organize several expeditions to view solar eclipses.

The society’s roster of presidents is a who’s-who of international science over the last couple of centuries. It includes George Darwin, the brother of Charles Darwin; Arthur Eddington, one of the first astronomers to puzzle out what powers the stars; Bernard Lovell, who established the world’s first major radio astronomy observatory; and Jocelyn Bell Burnell, who discovered the spinning stellar corpses known as pulsars.

Today, the society has about 4,000 members, including many outside the U.K. It remains one of the world\'s leading scientific societies — two centuries after its founding.

Script by Damond Benningfield

This year will offer up some great skywatching sights, including a brilliant showing by Mars, and the closest encounter between the planets Saturn and Jupiter in centuries. But it won’t offer good eclipses. There are no total lunar eclipses visible anywhere on the planet. The only lunar eclipses are so faint that they’re hard to see at all.

The first of them takes place today. It’ll be visible mainly across the eastern hemisphere. From the U.S., it’ll be in progress at moonrise across most of Alaska, but that’s about it.

This is known as a “penumbral” eclipse. The Moon will pass through Earth’s faint outer shadow — the penumbra. The shading is so faint, though, that most people won’t notice it.

All lunar eclipses belong to a cycle known as a Saros. The circumstances of each eclipse in the cycle repeat every 18 years and 11 days. There are only a couple of differences. One is that each eclipse is visible about a third of the way around Earth from the previous one. And the other is that the Moon moves slightly southward on each eclipse, so it passes through slightly more of Earth’s shadow.

This cycle began in 1749, with the first of a series of penumbral eclipses. It’ll soon move to partial eclipses, then total eclipses, where the Moon is totally immersed in the shadow. The first of those will take place on July 4th of 2308.

The Moon then begins moving out of the shadow. The cycle will end with a final penumbral eclipse — in 3011.

Script by Damond Benningfield

The pre-dawn sky might have you seeing red for the next few weeks — or at least reddish orange. That’s because two colorful pinpoints of light will sweep past each other. One of them is Mars, the Red Planet. And the other is its “rival,” Antares — a red-supergiant star.

The two bodies achieve their color in different ways.

Mars is a ball of solid rock, like Earth. Much of its surface is covered by iron-rich dust. Exposure to water has “rusted” the iron, giving it an orangey color.

Antares, on the other hand, is a ball of gas that’s much bigger than the Sun. Its outer layers are quite cool as stars go — a temperature that makes Antares look reddish orange.

The close match in color between the two bodies is what gave Antares its name. “Antares” means “rival of Ares” — the Greek god of war. In Rome, he became known as Mars. So Antares is the rival of Mars. The color of the planet Mars reminded skywatchers of blood, which is why they associated the planet with the war god. And since Antares was about the same color, and Mars regularly passed by it, it made sense to think of the star as being like Mars — a rival for a bright orange planet.

Look for Mars and Antares in the southeast an hour or two before sunrise tomorrow. Mars will stand almost directly above Antares, by less than the width of your fist held at arm’s length. Mars is sliding down to the lower left, so it’ll stick fairly close to its colorful rival for a few weeks.

Script by Damond Benningfield

The Moon pays a call on one of the horns of the bull tonight. As night falls, the star Zeta Tauri is quite close to the right or upper right of the Moon. It’s so close that you might need to blot out the Moon with your hand to see it.

Zeta Tauri represents the tip of one of the horns of Taurus, the bull — at least in western mythology. In China, it was known as Tianguan — the “celestial gate.” A couple of years ago, the International Astronomical Union adopted that as the star’s official name.

Actually, the system consists of two stars, but the proper name applies only to the brighter one. The second star is Zeta Tauri B.

We can’t see star “B,” even through the biggest telescopes. That’s because it’s much fainter than Tianguan, and the stars are quite close together — they’re only about as far apart as Earth is from the Sun.

Astronomers discovered the companion by breaking the light from the system into its individual wavelengths or colors. That revealed two patterns of light. They shift back and forth as the stars orbit each other.

The main star is about 11 times as massive as the Sun, and more than four thousand times brighter. Before long, it will explode as a supernova. It will leave behind a super dense corpse known as a neutron star.

The fainter star may already have expired. Astronomers can’t quite work out its type. But it could already be a corpse — a neutron star or a white dwarf — a dead star at the tip of the bull’s horn.

Script by Damond Benningfield

Our home galaxy, the Milky Way, contains hundreds of billions of stars. So no matter where you point a telescope, you’re going to see many of those stars. And they can appear so close to each other that it’s hard to tell if they’re related, or if they just happen to line up in the same direction.

Consider Aldebaran, the bright “eye” of Taurus, the bull. It’s close to the right of the Moon this evening, so you can’t miss it.

Over the centuries, astronomers have plotted five stars that appear quite close to Aldebaran. They’ve speculated that the stars are companions to Aldebaran — bound to the giant star by their mutual gravitational pull. Detailed observations, though, suggest that most of the stars aren’t related to Aldebaran at all — and perhaps none of them are.

It takes a while to figure out which stars are bound to each other. Astronomers track the motions of each star across the sky. Stars that are companions stick close together. But the motions can be quite subtle, so it can take decades to work them out.

And when stars appear especially close together, the problem is even tougher. One of the stars that’s close to Aldebaran may actually be a binary companion. But the star is quite small and faint, so its light is overwhelmed by Aldebaran’s. That makes it hard to measure the fainter star’s motion and distance. So despite decades of observation, no one is quite sure whether Aldebaran has a companion star — or moves through space alone.

Script by Damond Benningfield

You don’t have to look into the sky to learn about Earth’s interactions with the rest of the solar system. Sometimes, all you need are some ancient clam shells. Fossil shells found in Florida suggest that it was pounded by one or more big space rocks a couple of million years ago.

The story began in 2006. Mike Meyer, a college student, was gathering fossils from a quarry near Sarasota, on the Gulf coast. Some of the clam shells he found contained tiny glass beads. No one could tell Meyer what the beads were, so he chucked them in a box.

A couple of years ago, Meyer decided to take a closer look at them. He and some colleagues subjected the beads to a battery of tests. They found that the beads probably are microtektites, which form in a collision between Earth and an asteroid.

Such an impact blasts huge amounts of debris into the atmosphere. It also melts some of the material. As it falls back to Earth, molten glass can be sculpted into tiny beads.

The Florida beads contain a lot of sodium. That suggests they formed nearby — perhaps from impacts in beds of salt off the Florida coast. The impacts may have taken place two million to three million years ago, although it’ll take more tests to confirm the dates.

So far, no one has found any other microtektites in Florida. That could mean that no one has been looking for them. But researchers may start keeping an eye out for them in the fossil clams they dig up along the Florida coast.

Script by Damond Benningfield

Break out the umbrellas, the swimsuits, and the sunscreen. Sun and Earth are closest for the entire year today, so we’re getting a little extra warmth from our favorite star.

Earth is at a point in its orbit called perihelion — a word that means “closest to the Sun.” We’re about a million-and-a-half miles closer than the average distance.

And as you might expect, we get a little extra solar energy from that proximity — about three percent more than we average over the course of a year.

At this time of year, though, the Sun’s rays are falling most directly on the southern hemisphere, so it gets the bulk of the energy. But the oceans and atmosphere absorb much of that extra heat and transport it around the globe. That helps keep the two hemispheres in balance.

The distance to the Sun changes because Earth’s orbit is an ellipse — like a slightly stretched-out circle. In fact, all the planets follow elliptical orbits. But the “stretching” varies from planet to planet.

Venus has the most nearly circular orbit, so Venus’s distance from the Sun varies by less than one percent. Mercury, on the other hand, has the most lopsided orbit — its distance from the Sun varies by a fifth. So peak daytime temperatures on the airless planet vary by hundreds of degrees — all thanks to the changing distance to the Sun.

Our distance to the Sun will be increasing for months — until we reach our farthest point in early July.

Tomorrow: Florida clams.

Script by Damond Benningfield

A land of supergiants soars across the south on winter nights. Orion is one of the more prominent constellations. That’s because the seven stars that outline the hunter's body are all current or future supergiants — the biggest, brightest, and heaviest of all stars.

Three of them form Orion’s Belt — a short line that extends straight up from the eastern horizon at nightfall. Orange Betelgeuse is to the left of the belt, with Bellatrix to the upper left. Blue-white Rigel, the brightest of the seven, is to the right of the belt, with Saiph to the lower right.

All seven stars formed from the same complex of gas and dust — clouds that span hundreds of light-years. They’re near the inner edge of the Orion Arm — one of the Milky Way Galaxy’s spiral arms. A wave is passing through the arm, squeezing the clouds. That causes them to collapse and give birth to new stars.

The brightest of Orion’s supergiants is Alnilam, which is at the bottom of the belt. It’s about 40 times as massive as the Sun, and half a million times brighter. It looks fainter than Betelgeuse and Rigel because it’s farther away. And Betelgeuse is the biggest of the seven — about 900 times the Sun’s diameter.

All seven of the stars likely face the same fate: Each will explode as a supernova. And it won’t take long. Massive stars age quickly, so Orion’s supergiants are likely to explode within a few million years — turning the land of the supergiants into a graveyard.

Script by Damond Benningfield

A meteor shower that might have been born with the destruction of a comet is at its best tonight. It typically reaches peak rates of about a hundred “shooting stars” per hour — one of the busiest of all meteor showers. But the peak typically lasts no more than a couple of hours, so it’s a tough shower to watch.

It’s called the Quadrantid shower, for the extinct constellation Quadrans Muralis. It’s part of present-day Bootes, which climbs into view in the wee hours of the morning. If you trace the meteors across the sky, their paths all intersect in that region.

The Quadrantids appear to be associated with an asteroid. Recent research suggests it’s a fragment of a comet that split apart more than 500 years ago. The break-up created a cloud of rocky debris that spread out along the comet’s orbit. That path is turned almost perpendicular to Earth, so we punch through it like a runner breaking the tape at the end of a race, sweeping up some of the comet dust.

The trail of debris is pushed around by the powerful gravity of Jupiter, which might have been responsible for the comet’s breakup. By a thousand years from now, it might push the meteor stream so much that it’ll no longer intersect Earth’s orbit — and the Quadrantids will disappear.

For now, look for the meteor shower late tonight. The best view comes in the wee hours of the morning. And the Moon is nowhere in sight — leaving perfect conditions for the celestial fireworks.

Script by Damond Benningfield

That’s the introduction to a radio play based on a story by Isaac Asimov, one of the most influential science-fiction writers ever — and one of the busiest. He wrote or edited 500 books and thousands of short stories and magazine articles.

Asimov was born 100 years ago today, in Russia. His family emigrated to the United States when he was three.

During World War II, Asimov worked as a civilian chemist for the Navy. Afterward, he earned a PhD in biochemistry, and joined the faculty of Boston University — a position he held for decades. He discovered, though, that he preferred writing to research. He published his first short story in 1939, and his first novel in 1950.

Asimov is best known for his three laws of robotics, and for the “Foundation” series — stories that chronicled the fall of a galactic empire and the start of another.

Asimov didn’t limit himself to science fiction, though. He also wrote mysteries and other fiction. And in the 1960s he turned mostly to science fact, with forays into history, religion, and even Shakespeare.

Asimov died in 1992. But his fellow scientists have named an asteroid and a crater on Mars in his honor — tributes to an author who transported millions of readers to the stars.

Script by Damond Benningfield