StarDate

Centaurus A is one of the brightest galaxies in the night sky. It’s especially bright at radio wavelengths. A supermassive black hole in its heart shoots out long “jets” of charged particles. They produce radio waves. And the first person to identify Centaurus A as a radio galaxy was born 100 years ago today.

John Bolton was born in Sheffield, England. He studied math and physics, then enlisted in the Royal Navy during World War II. He did research and development work on radar, then served on a ship in the Pacific. The ship was in Australia when the war ended, so Bolton decided to stay.

Radio astronomy barely existed then. But war-surplus radar equipment — and scientists who knew how to use it — boosted the field. Bolton built a telescope that used the ocean to reflect radio waves into his detectors. With it, he discovered many new radio sources.

To understand those sources, though, astronomers needed to link them to photographs. So Bolton and his team narrowed the field of view, allowing them to pinpoint the location of radio objects. That led to the discovery that some of the objects were galaxies — like Centaurus A.

Bolton later built and directed a much bigger radio telescope. It contributed to the discovery of quasars and many other intriguing objects — through radio.

From the southern half of the U.S., Centaurus A is due south at nightfall, barely above the horizon — a noisy galaxy powered by a black hole.
 

Script by Damond Benningfield

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Astronomers have caught several planets in the act of destruction. The planets are so close to their parent stars that their atmospheres are being blown out into space. But they’ve also observed one planet that’s still growing. Hot gas and dust are crashing onto its surface, adding to the planet’s heft.

PDS 70b is already pretty hefty. Estimates say it’s several times the mass of Jupiter, the giant of our own solar system. But it’s continuing to grow. And that’s thanks to the age of its parent star, PDS 70.

The star is only about five million years old. In fact, it’s not yet a full-fledged star. It’s encircled by a wide disk of gas and dust. Some of that material is falling onto the star, while some of it has formed the planet. It’s also formed a disk around the planet.

In a study released last year, astronomers at the University of Texas and elsewhere observed the system with Hubble Space Telescope. They snapped a picture of it at ultraviolet wavelengths, which are invisible to the human eye. The strong ultraviolet light from the planet implies that material is still falling onto the planet from its disk. It may be funneled inward by magnetic fields. The process seems to be slowing down, though — suggesting that PDS 70b is just about fully formed.

The system is in the constellation Centaurus, which is low in the south at nightfall. It’s about 370 light-years away, though, so it’s much too faint to see without a telescope.
 

Script by Damond Benningfield

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Soon after the closest star to the Sun was discovered, in 1915, astronomers began suspecting that it was gravitationally bound to two other stars. But it’s been hard to confirm that suspicion.

The stars are the binary system Alpha Centauri A and B, and Proxima Centauri. A and B look like a single pinpoint — one of the brightest in the night sky. Proxima is a cosmic ember so faint that you need a good telescope to see it.

Proxima is just four and a quarter light-years from Earth. The other two are a bit farther. But all three stars move through space in the same way.

Proxima is sometimes called Alpha Centauri C, indicating that it’s the third member of the system. Because of the distance between it and the stars A and B, though, that designation has been shaky. We hadn’t seen enough of Proxima’s possible orbit to confirm its membership.

Some recent studies have solidified that membership, though. One, released last summer, carefully measured the details of the system. Among other things, it found that A and B are about half a percent farther than earlier studies had tallied — a difference of more than a hundred billion miles. It also found that A and B are slightly closer to each other. And it refined the distance from Proxima to the other two stars. The numbers increase the odds that Proxima is a member of the Alpha Centauri system — appearing to confirm that our nearest neighbors are triplets.
 

Script by Damond Benningfield

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Proxima Centauri is our closest neighbor star — just four and a quarter light-years away. By astronomical standards, that’s just down the block. Yet the star is so puny that you need a strong telescope to see it.

What scientists would really like to see are the star’s three known planets. They’re like something from Goldilocks. The closest planet is too hot for life. The farthest planet is too cold. But the middle planet could be just right.

Proxima produces a tiny fraction as much energy as the Sun does. So the “just-right” planet, Proxima Centauri b, is quite close in — about five percent of the distance from Earth to the Sun. That should place it in the star’s habitable zone. That’s the distance where temperatures are just right for liquid water — a key ingredient for life.

The planet is a little bigger and heavier than Earth, which could make it a good home for life. And it’s probably a little older than Earth, so there’s been time for life to take hold.

On the other hand, Proxima Centauri produces huge eruptions of radiation and charged particles. They could blast away any atmosphere the planet ever had and sterilize the surface.

A team is working to send a fleet of postage-stamp-size spacecraft to Proxima Centauri. Powered by lasers on Earth, it might take as little as 20 years to make the trip. The craft could beam back pictures of the star and its planets — revealing details about our close neighbors.
 

Script by Damond Benningfield

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Centaurus is home to some of the night sky’s great treasures, including our closest neighbor stars and the Milky Way’s largest globular cluster. Yet most of us in the United States don’t get to see them. They’re so far south that they always stay below the horizon.

Centaurus represents a centaur — a mythological creature that was half man, half horse. According to some versions of the story, he was Chiron — the wisest of all the centaurs. He tutored Hercules, Perseus, and many other young heroes in music, medicine, and other arts. But Hercules accidentally shot Chiron with a poisoned arrow. Chiron was immortal, so he suffered in agony. Zeus eventually allowed him to die — then placed him in the stars.

The centaur’s greatest treasure is Alpha Centauri — a system of three stars. They’re the nearest stars beyond the Sun. The closest of the three is Proxima Centauri, just four and a quarter light-years away. It’s too faint to see without a telescope. But the other two stars, which are a touch farther, are bright. You need to be in Hawaii or in the southern tips of Texas or Florida to see them.

Centaurus also is home to Omega Centauri — a cluster of several million stars. It is bright enough to see with the eye alone. Right now, it’s just above the southern horizon as night falls across the southern third of the country, and looks like a fuzzy star.

We’ll have more about the centaur tomorrow.
 

Script by Damond Benningfield

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Charles Greeley Abbot was ahead of his time. He was interested in the Sun — not so much as a star, but for more practical reasons. He wanted to use it to improve weather forecasts, and to power everyday devices. He received more than 15 patents related to solar energy — the last when he was 100 years old.

Abbot was born 150 years ago today, on a farm in New Hampshire. He quickly showed that he was clever and inventive; at age 13, he designed and built a forge to help repair tools.

Abbot studied physics at MIT. There, he met Samuel Pierpoint Langley, director of the Smithsonian Astrophysical Observatory. He soon joined Langley, then took over the director’s job after Langley died. And in 1928, he became secretary of the entire Smithsonian.

Abbot was especially interested in how much energy the Sun produced, and how that changed over time. He thought such knowledge could help provide better weather forecasts. So Abbot established three observatories to study the question, then spent decades analyzing the results. He concluded that the Sun’s energy output varied by several percent. He turned out to be wrong, though — the variation is only a fraction of one percent.

Abbot created many solar-powered devices, and wrote about solar power plants. He patented a solar cooker, a boiler, and a system to remove salt from seawater. Abbot received his final patent less than two years before he died, at age 101.
 

Script by Damond Benningfield

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A comet that fell apart almost three decades ago could put on a good show tonight: a meteor shower.

The comet has a mouthful of a name: 73/P Schwassman-Wachmann 3. It was discovered in 1930. Astronomers quickly looked for a meteor shower produced by the comet. And they found it. It was called the Tau Herculid shower because its meteors appeared to “rain” into the sky from near a star in Hercules.

In the decades since, little has been heard of the shower. But in 1995, the comet disintegrated, spewing out huge amounts of dust.

Some models say that could have squirted enough material toward Earth’s orbit to trigger a meteor shower tonight, as the grains of dust ram into the atmosphere. In addition, we may pass through a couple of clumps of dust released in the 1890s.

Astronomers can’t say for sure that we’ll see anything. But if we do, the peak should come around midnight — a little later in the east, a little earlier in the west. Estimates of the number of meteors range from a few to a few thousand.

The central point of the shower has drifted toward the bright star Arcturus, which will be high in the southwest. But the meteors can blaze across any part of the sky, so you don’t have to look toward Arcturus to see them.

The shower will be better from the southern U.S. because twilight will end earlier than in the northern states. But there’s no moonlight to interfere with the show — sparks from a dead comet.
 

Script by Damond Benningfield

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A wayward rocket gave the people of El Paso and Ciudad Juarez a scare 75 years ago. It was launched from New Mexico and was supposed to head north. Instead, it veered south, then crashed a half mile from a cemetery and an airport outside Juarez.

The rocket was a V-2 — a German World War II “terror weapon.” After the war, the U.S. brought in German rocket experts and several train cars full of rocket parts. The army then set up a test site at White Sands Proving Grounds, in New Mexico.

Several V-2s had been launched before the test of May 29th, 1947 — some successful, some not. A flight just two weeks earlier went awry, with the rocket crashing on the outskirts of Alamogordo, New Mexico.

The May 29th flight had been delayed by engine troubles. It finally launched at 7:30 p.m. Something went wrong with its gyroscope, though, so it headed off course.

It streaked across El Paso, then plunged to Earth just south of the city, creating a blast that was heard and felt many miles away. The concussion rattled buildings across El Paso and Juarez, broke windows, and even stopped a clock in the El Paso sheriff’s office. It gouged a crater 50 feet wide and 24 feet deep. No one lived near the impact site, though, so no one was injured.

The Army quickly cleaned up the mess, apologized, and paid for the damages. And it set up new safety procedures to prevent a repeat — keeping the population safe from off-course rockets.
 

Script by Damond Benningfield

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The planet Saturn is tailing the sea goat these days. It’s just a couple of degrees from Deneb Algedi, the star that represents the tail of Capricornus, the sea goat. And Saturn will stick with the star for quite a while.

They’re in the southeast at first light now. Saturn looks like a bright golden star, with Deneb Algedi — an Arabic name that means “tail of the goat” — to its lower right. They’re separated by about two degrees — the width of your finger held at arm’s length. The rest of Capricornus, which forms a wide triangle, spreads to the west.

Deneb Algedi actually consists of four stars. Two of them form a tight binary. One of those stars is bigger, brighter, and heavier than the Sun. The other is fairly similar to the Sun. The other two stars in the system are far away from the binary.

Saturn has been hanging close to Deneb Algedi for a couple of months. And they’ll stay about as close as they are now for a couple of months longer.

After that, Saturn will slide to the west of the star — across the top line of the sea goat’s triangle. That’s because the orbital motions of Earth and Saturn will combine to make the planet appear to slide in reverse against the background of stars. That will end around Halloween, when Saturn will resume its normal eastward motion. That will make it cozy up to Deneb Algedi again late this year and into 2023 — as Saturn continues to “tail” the sea goat.
 

Script by Damond Benningfield

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Two planetary neighbors will get especially neighborly over the next few mornings. They’ll huddle as close as half a degree from each other — less than the width of a pencil held at arm’s length.

The planets are low in the eastern sky at dawn. The brighter one is Jupiter, the giant of the solar system. Only the Moon and Venus shine brighter. The other world is Mars. It’s close to the lower right of Jupiter tomorrow, and even closer on Sunday. It shines with an orange glow, so it’s hard to miss.

Jupiter might have had a big influence on Mars’s formation.

Today, Jupiter is almost half a billion miles from the Sun — more than three times Mars’s distance. But there’s evidence that when the solar system was young, Jupiter might have moved much closer to the Sun — pretty close to the present-day location of Mars.

The evidence includes Mars itself. The planet is only about half the size of Earth — smaller than it should be. It’s possible that it was kept smaller by Jupiter. As it moved inward, the giant planet would have swept away the small chunks of ice and rock that coalesced to form planets. That would have locked Mars at its current size.

Jupiter’s migration also scattered material between itself and Mars, preventing the birth of another planet — and forming the asteroid belt.

Mars and Jupiter will remain fairly close for a few more days. After that, Jupiter will pull away, leaving Mars behind.
 

Script by Damond Benningfield

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