StarDate

The Moon has a familiar companion the next couple of evenings: Regulus, the heart of Leo, the lion. The bright star stands to the upper left of the Moon tonight, and closer to the right or lower right tomorrow night.

The Moon passes by Regulus about once a month. That’s because Regulus is just a whisker away from the ecliptic — the Sun’s path across the sky. The Moon stays close to the ecliptic as well, so it swings past Regulus on every loop through the starry background.

Not all of those encounters happen at night — some take place in daylight. In fact, as you see the Moon in the sky the next couple of afternoons, know that Regulus is right there with it.

The Moon also will pass Regulus in daylight in August — on the 21st, to be precise. On that day, though, for viewers in parts of the United States, Regulus will briefly pop into view. That’s because the Moon will pass directly in front of the Sun, creating a total solar eclipse. The path of totality will be a few dozen miles wide, and stretch from Oregon to South Carolina.

As the Moon covers the Sun, the sky will grow dark. The Sun’s outer atmosphere, known as the corona, will form a silvery glow around the intervening Moon. Several bright planets will pop into view — Venus and Mars on one side of the Sun, and Mercury and Jupiter on the other.

And Regulus will be there as well, partially immersed in the glow of the corona — not far from its frequent companion, the Moon.

Script by Damond Benningfield

Fifty years ago this month, a cluster of storms rotated into view on the eastern limb of the Sun. Over the next two weeks, it produced a series of explosions and outbursts that bathed Earth in radiation and charged particles. That produced bright auroras, disrupted radio communications, and interfered with military radar. In fact, some commanders were concerned that the Soviet Union was jamming the radars — perhaps as a prelude to a nuclear attack.

Solar storms are bad for technology. They can knock out power grids on the ground, damage or destroy satellites, interfere with GPS and other radio signals, and cause other mischief.

The 1967 solar storms were some of the biggest of the 20th century. Many of their effects on Earth lasted for days or weeks. They were a particular problem for a line of early-warning radar stations near the Arctic Circle. On May 23rd, for example, the radars were looking almost directly into the Sun. The solar radio interference left the radars eating static.

And that made the military nervous. A study published last year says it prepared to launch bombers to counter a possible Soviet attack. But a new arm of the Air Force, which studied space weather, convinced leaders that the interference came from the Sun, not the Soviets. So the bombers stayed on the ground.

The incident spurred the Air Force to develop an even better system for studying and forecasting space weather — a step to help prevent any accidental “star wars.”

Script by Damond Benningfield

A star can “die” more than once. And the second death can be just as impressive as the first. It can produce a brief outburst that’s easily visible across billions of light-years of space.

Such an outburst was detected three years ago in Corona Borealis, the northern crown. The constellation is in the east as night falls at this time of year, and crowns the sky a few hours later.

A space telescope detected a gamma-ray burst — a flash of the most powerful form of energy. For a couple of seconds, it appeared brighter than any other single object in the universe. But follow-up observations from space and the ground saw nothing — no exploding star or anything else that might have produced the gamma rays.

The brightness and brevity of the blast, and the lack of a visible counterpart, suggested a source: the merger of two dead stars — either two neutron stars, or a neutron star and a black hole. Both kinds of objects form when a massive star explodes as a supernova, crushing its now-dead core. Such objects are no more than a few miles across, but several times as massive as the Sun.

When the two dead stars in Corona Borealis collided, they produced a brief but brilliant burst of gamma rays. The rays were “beamed” into space in narrow jets. We saw the outburst only because one of the jets happened to beam in our direction. If it hadn’t, we wouldn’t have seen anything — and the “re-death” of these two stellar corpses would have remained hidden.

Script by Damond Benningfield

A pretty little semicircle of stars crowns the sky on spring and summer nights: Corona Borealis, the northern crown. It’s in the east as night falls right now, but stands high overhead a few hours later. In a couple of months, it’ll be overhead at nightfall.

Most of the semicircle isn’t very bright — you need pretty dark skies to see it. It stands out because of the tight pattern, with a fairly bright star at its center: Alphecca, “the bright one.”

Alphecca’s actually a binary — two stars locked in a gravitational embrace. The heavier of them is about three times as massive as the Sun, thousands of degrees hotter, and dozens of times brighter. Its companion is a little smaller, cooler, and fainter than the Sun.

The stars are quite close together — an average of about half the distance between the Sun and its closest planet, Mercury. They orbit each other once every 17 and a half days.

And they’re lined up in such a way that we see the fainter star eclipse the brighter one. When that happens, Alphecca dims by a few percent. That’s not enough for most of us to notice with the eye alone, but it’s an easy catch for astronomical instruments.

Instruments also detect a disk of debris around the stars. It extends billions of miles out into space. The disk consists mainly of small grains of dust — material left over from the formation of Alphecca itself.

Tomorrow, we’ll talk about another pair of stars in Corona Borealis that blew itself up.

Script by Damond Benningfield

While the Moon orbits Earth and Earth orbits the Sun, the Sun isn’t exactly standing still. In fact, it’s racing around the center of the Milky Way galaxy, carrying Earth and the other planets with it.

The solar system inhabits the most luminous part of the Milky Way: its disk, which includes the beautiful spiral arms and most of the galaxy’s stars. It’s shaped like a pancake, except this pancake is enormous: at least a hundred thousand light-years across and a couple of thousand light-years thick.

We’re about 27,000 light-years from the galaxy’s center — nearly halfway to the edge of the disk. And we’re near the midplane of the disk — the line that divides it into northern and southern halves. Estimates vary, but the solar system is probably between 40 and 90 light-years north of the midplane. That’s not very far when compared to the thickness of the disk.

Still, with every passing minute, we’re moving higher. As the Sun orbits the galactic center, it slowly bobs up and down, like a horse on a merry-go-round. And for millions of years, we’ve been moving up. Eventually, we’ll reach a peak altitude and start to head back down. But we’ll never venture beyond the bounds of the Milky Way’s starry disk.

And under dark skies, that disk is visible as the hazy band of light known as the Milky Way. It’s quite low in the sky this evening, but arcs high overhead before dawn tomorrow. It’ll be in better view in the evening sky as we head into summer.

Script by Ken Croswell, Copyright 2017

Johannes Hevelius saw things that no one else did. Perhaps that was because he had a vivid imagination. Or perhaps it was because he consumed a lot of the famous beer he brewed. But whatever the reason, in the late 17th century he drew 10 new constellations. All of them filled in regions where no constellations had existed before — relatively dark areas of the sky with almost no bright stars.

And seven of those constellations are still with us today. An example is Lynx, which is in the west and northwest at nightfall. Although it’s faint, you can find its location with the help of three bright stars below it: Pollux and Castor, the twins of Gemini, which are almost due west; and even-brighter Capella, the leading light of the charioteer, to their lower right.

Hevelius, who didn’t use a telescope, counted 19 stars in that region, between Capella and the Big Dipper. He linked some of those stars in a zigzag pattern. And showing that he had a sense of humor, he called the new constellation Lynx, after the wild cat. He didn’t pick the name because the pattern looked like a lynx — it was because the viewer needed the eyes of a lynx to see it.

And thanks to light pollution, it’s even harder to see today. To pick it out, you need a nice, dark sky, far from city lights. From the suburbs, you might make out a few stars, especially the brightest one, Alpha Lyncis. It’s an orange giant that’s 200 light-years away — the brightest “spot” of a faint cat.

Script by Damond Benningfield

A project known as Breakthrough Starshot hopes someday to use a powerful beam of energy to propel a tiny probe to another star. A recent study says that other civilizations might already be doing that, but on a much larger scale — and that we might have seen some of those beams.

Two researchers at Harvard considered the objects known as fast radio bursts. Astronomers have seen about a score of them, all in other galaxies. They’re intense outbursts of radio waves that last only a tiny fraction of a second. They could be powered by exploding stars, collapsing neutron stars, or some other exotic objects.

But the Harvard astronomers wondered if the bursts could have an artificial origin. And they concluded that it’s possible.

Their idea is that a civilization would build a starship propelled by a giant sail. A beam of radio waves would “push” the ship just as the wind pushes sailing vessels here on Earth. Occasionally, the radio beam would sweep past Earth — producing a radio burst.

If the radio beam were powered by solar energy, it would require a collector that’s about twice the diameter of Earth. Building and operating such a system wouldn’t be easy — but it’s within the realm of possibility. And the payoff could be big: it could propel a million-ton ship to a good fraction of the speed of light.

The researchers aren’t saying that fast radio bursts really are produced by other civilizations — only that it’s a possibility worth checking.

Script by Damond Benningfield

[AUDIO: FRB “chirp”] That sound comes from a distant galaxy — perhaps from the corpse of a once-mighty star. It’s one of a couple of dozen outbursts captured from the galaxy — a cosmic puffball that’s three billion light-years away. And it’s helping astronomers understand a new class of objects, known as FRBs — fast radio bursts.

So far, astronomers have discovered only about a score of these objects. They produce intense bursts of radio waves that last only a few thousandths of a second. But until recently, no one could pinpoint the location of even a single burst. Without knowing how far away the bursts are, it’s impossible to know how powerful they are. That means it’s also impossible to know what they are.

But earlier this year, a team of astronomers reported that one FRB has popped off a couple of dozen times in the last few years. That allowed the team to pinpoint the FRB’s location, inside a dwarf galaxy.

Such galaxies give birth to lots of stars. Some of the stars are big and heavy, so they live short, bright lives, then explode. Some of them leave dense corpses that are highly magnetized.

The astronomers say that one of these corpses could produce the outbursts — perhaps as it interacts with the galaxy around it.

This scenario hasn’t been confirmed, though. And so far, there’s no way to know if all FRBs are formed in the same way — there could be several explanations for them. We’ll talk about one of those tomorrow.

Script by Damond Benningfield

A project that’s beginning this month will compile dossiers on hundreds of supernovae. That should give astronomers a better picture of the types of stars that explode, how supernovae interact with their surroundings, and how they seed the cosmos with chemical elements.

The Global Supernova Project is a collaboration of about 150 astronomers around the world. It’ll use about 30 telescopes to monitor supernovae after other projects discover them.

The backbone of the project is the Las Cumbres Observatory — a network of 18 telescopes, including one at McDonald Observatory, with mirrors up to two meters in diameter. Because they’re spaced around the globe, they can follow a supernova around the clock.

That’s especially important in the first days after a supernova explodes. Those early moments reveal details about the original star, such as its composition and structure. But the chemical signatures from some of its expelled materials fade quickly, and the radioactive decay of nickel and other elements soon dominates the light from the supernova debris.

This is a follow-up to an earlier project, which ended last month. During its three-year run, it studied more than 400 supernovae. Among other things, it discovered several new classes of supernova.

The new project is expected to see about 600 supernovae, also over a three-year period. Those observations should help astronomers more fully understand these powerful cosmic blasts.

Script by Damond Benningfield

For the first three decades of the Space Age, Venus was the belle of the ball. Through the 1980s, the United States and the Soviet Union dispatched about 30 missions to the brilliant planet. In fact, Venus was the target of the first successful mission to any planet, and the Soviets landed several craft on its surface.

Since then, though, Venus has been left pretty much alone. A few craft have peeked in when they used Venus to get gravitational “kicks” to other planets. But Venus has been a main target for only a handful of missions.

There are several reasons for the change. One is the success of many of the earlier missions, which answered a lot of questions about the planet.

Another is that it’s tough to build something that can last for very long on the surface of Venus. Because of its hot, dense, toxic atmosphere, nothing has survived for more than about an hour. And it’s hard to explore a world if you only get hour-long peeks.

Some recent work has produced electronics that might be able to survive much longer. In tests, they lasted for weeks in a simulated Venus environment. If those systems can be certified for spaceflight, they might make it possible to get our first long look at the surface — perhaps rekindling the infatuation with the beautiful planet.

And Venus is in good view in the early morning sky. It’s the brilliant “morning star.” Tomorrow, it perches quite close to the crescent Moon — a great way to greet the dawn.

Script by Damond Benningfield