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StarDate Online - Your guide to the universe





 



The Argo

Thu, 23 Mar 2017 06:00:00 +0000

Argo, the ship of Jason and the Argonauts, sails across the south tonight. It originally was a single constellation, but astronomers broke it into four smaller ones: Carina, the keel; Vela, the sail; Puppis, the poop deck; and Pyxis, the compass.




Major Storm

Thu, 23 Mar 2017 05:00:00 +0000

A storm erupts on the Sun in this August 2012 image from a Sun-watching spacecraft. The storm includes a solar flare (bright white are) and a solar prominence (the loop extending above the Sun's surface). If a major storm was aimed at Earth, it could damage much of our electrical infrastructure, causing massive economic damage. [NASA/GSFC]

(image)



Storm Impact

Thu, 23 Mar 2017 05:00:00 +0000

Major Storm A storm erupts on the Sun in this August 2012 image from a Sun-watching spacecraft. The storm includes a solar flare (bright white are) and a solar prominence (the loop extending above the Sun's surface). If a major storm was aimed at Earth, it could damage much of our electrical infrastructure, causing massive economic damage. [NASA/GSFC] A major hurricane can cause tens of billions of dollars in direct damages. And it can cause tens of billions more in indirect damages — losses to the economy caused by destroyed businesses, fouled roads, power outages, and other problems. A major storm on the Sun, however, has the potential to dwarf those losses. A recent study by the American Geophysical Union found that under the right circumstances, a solar storm could trigger economic damages of up to almost 50 billion dollars a day. The Sun produces storms all the time — big eruptions of charged particles that race outward at millions of miles per hour. Most of the time, these storms miss Earth. But when they do hit, they can knock out satellites, disrupt communications and air travel, and even knock out power grids. In 1989, an especially big storm knocked out power to Quebec. In recent years, there’s been concern that if a monster solar storm hit Earth, it could knock out power across most of the United States. Not only that, but the currents might fry equipment that could take months to replace. That could leave big chunks of the country powerless for weeks or months. The recent report looked at the economic impact of such an outage. It found that damages could hit anywhere from a few billion dollars a day, up to 50 billion. About half of that loss comes from a ripple effect that impacts vendors, customers, and others — a major impact from a stormy Sun.   Script by Damond Benningfield Keywords: Space WeatherSunSunspots and Solar FlaresStarDate: Thursday, March 23, 2017Teaser: Projecting damages from a big storm [...]



Winter Circle

Wed, 22 Mar 2017 06:00:00 +0000

Spring has already sprung, but a great pattern of stars named for winter still dominates the western evening sky. The Winter Circle includes some of the most prominent stars of all, including Sirius, the brightest star in the night sky.




The Next Generation

Wed, 22 Mar 2017 05:00:00 +0000

The next big space telescope, James Webb, is being prepared for launch next year. And the one after that, which will look like a twin of the venerable Hubble telescope, is being developed.

Yet even these instruments will leave many questions unanswered. So NASA is already planning the next generation of space telescopes. They’ll be bigger than anything launched before, and provide capabilities far beyond Hubble or Webb.

A year ago, NASA picked four teams to outline concepts for the next big space telescope. They’ll keep at it for two more years. After that, the National Academy of Sciences will review the ideas and recommend which one to develop.

One telescope would be like a super-sized version of Hubble. It would use a segmented mirror that could be as tall as a five-story building to look at a wide range of wavelengths. That would allow it to detect signs of life on planets in other star systems and watch the evolution of galaxies and black holes.

Another concept would also provide details on other planets. It could photograph planets in Earth-like orbits, and monitor their atmospheres for signs of life.

The other ideas would look only at wavelengths that are invisible to the human eye. That would allow them to study the earliest galaxies, or the disks of superhot gas around black holes.

All of this will take time, though. Whichever concept NASA eventually picks, the telescope won’t launch until at least the 2030s.

 

Script by Damond Benningfield

StarDate: 
Wednesday, March 22, 2017
Teaser: 
Space telescopes: the next generation



Milky Way Clouds

Tue, 21 Mar 2017 06:00:00 +0000

The stars of the Milky Way intertwine with clouds of gas and dust that can span many light-years. Some of them are bright and colorful; others, dark and quiet. The dark clouds are giving birth to new stars. They are dark because their gas is cold.




Looking Deep

Tue, 21 Mar 2017 05:00:00 +0000

Earth and the solar system’s other rocky planets probably grew as smaller blobs of rock and metal slammed together, forming ever larger bodies. As they grew, gravity pulled heavier materials — iron and nickel — toward the middle, forming their cores. Lighter materials floated toward the top, forming the mantle and crust.

We can’t actually see the cores of these worlds. But a new NASA mission may be able to show us the next-best thing: the core of a possible protoplanet, one of the building blocks of planets.

Psyche will orbit an asteroid of the same name. The asteroid is a chunk of metal about 150 miles in diameter — the biggest metallic asteroid in the solar system. It could be the surviving core of a protoplanet. The little object’s outer layers could have been blasted away by collisions with other asteroids, leaving only its dense metallic core.

Observations by ground-based telescopes show that 90 percent of its surface is made of iron. The rest is made of various minerals. A close-up inspection of those minerals could confirm that Psyche is the leftover core of a protoplanet. On the other hand, it could show that the minerals came from impacts with other asteroids, telling us that Psyche never had a mantle or crust.

Either scenario will reveal more about how the inner planets formed and how they grew, and perhaps give us a hint of what their metallic cores look like.

We’ll talk about some other future missions of discovery tomorrow.

 

Script by Damond Benningfield

StarDate: 
Tuesday, March 21, 2017
Teaser: 
Looking into the hearts of planets



Crater

Mon, 20 Mar 2017 06:00:00 +0000

The constellation Crater, the cup, is visible this month in the southeastern evening sky. Its stars are faint, so you need dark skies to find it. To ancient European cultures, Crater represented the birthplace of storms.




Time Machines

Mon, 20 Mar 2017 05:18:07 +0000

Two new NASA missions will take a look at relics from the birth of the solar system. Lucy (left) will explore six Trojan asteroids, which share the orbit of Jupiter, while Psyche (right) will orbit the metallic asteroid 16 Psyche, which could be the battered core of a would-be planet that never formed. Both missions are scheduled for launch in the next decade. [SWRI/SSL/Peter Rubin]

(image)



Time Machine

Mon, 20 Mar 2017 05:00:00 +0000

Time Machines Two new NASA missions will take a look at relics from the birth of the solar system. Lucy (left) will explore six Trojan asteroids, which share the orbit of Jupiter, while Psyche (right) will orbit the metallic asteroid 16 Psyche, which could be the battered core of a would-be planet that never formed. Both missions are scheduled for launch in the next decade. [SWRI/SSL/Peter Rubin] Two new NASA missions are solar-system time machines. They’ll visit relics from the early solar system, providing a glimpse into the materials and processes that gave birth to the planets. Lucy will fly past seven asteroids — big chunks of rock, metal, and ice. One of them is in the asteroid belt, between the orbits of Earth and Mars. But the others share the orbit of Jupiter. Known as Trojans, they’re locked in place ahead of or behind the giant planet by the gravity of Jupiter and the Sun. Jupiter itself probably moved around a bit when it was young. It slid much closer to the Sun, then back out again. The Trojans might have formed with Jupiter and followed its migrations. On the other hand, they might have been captured by Jupiter as it moved. Studying them may help explain when and where they formed. In addition, the asteroids contain materials from the birth of the solar system. They probably haven’t changed much over the eons, so they preserve a record of conditions when the solar system was young. The mission will take advantage of existing technologies. Two of its instruments will be based on those used on New Horizons, which flew past Pluto. And a third will be based on another asteroid mission, Osiris-Rex. Lucy will launch in 2021, with arrival at Jupiter’s orbit six years later. By then, the second mission should be well on the way to its destination — the possible core of a would-be planet. More about that tomorrow.   Script by Damond Benningfield Keywords: AsteroidExplorer MissionsNASA and the American Space ProgramStarDate: Monday, March 20, 2017Teaser: Traveling to the early solar system [...]



Vernal Equinox

Sun, 19 Mar 2017 06:00:00 +0000

Those of us in the United States will wake up to a new season tomorrow. Spring begins at 5:29 a.m. CDT, which is the moment of the vernal equinox. It occurs when the Sun crosses Earth’s equator from south to north.




Vernal Equinox

Sun, 19 Mar 2017 05:00:00 +0000

Those of us in the United States will wake up to a new season tomorrow. Spring begins at 5:29 a.m. Central Daylight Time — the moment of the vernal equinox. It occurs when the Sun crosses Earth’s equator from south to north. It ushers in longer, warmer days here in the northern hemisphere, and shorter, cooler days in the southern hemisphere.

Over the course of a year, the Sun moves north and south across the sky. That’s only an apparent motion, though. The Sun itself isn’t moving. Instead, that motion is caused by Earth’s tilt on its axis.

As seen from the Sun, Earth doesn’t stand straight up and down. Instead, it slouches — by about 23 degrees. As Earth moves around the Sun, that causes the north and south poles to nod toward and away from the Sun. In June, the north pole aims toward the Sun. That brings longer days to the northern hemisphere. And in December, it’s the south pole that nods sunward, bringing less daylight to northern climes.

The equinoxes come halfway between these extremes. Neither pole dips sunward, so both hemispheres experience roughly equal amounts of daylight and darkness. In fact, that’s where the name “equinox” comes from — it means “equal nights.”

The equinoxes are also the only times of year when the Sun rises due east and sets due west. Unless you’re on the equator, it rises north or south of those points for the rest of the year.

So enjoy the first day of spring — the start of a new season under the Sun.

 

Script by Damond Benningfield

 

StarDate: 
Sunday, March 19, 2017
Teaser: 
Springing into a new season



Moon, Antares, Saturn

Sat, 18 Mar 2017 06:00:00 +0000

The planet Saturn is in good view early tomorrow. It looks like a bright star to the lower left of the Moon at first light. The bright star Antares stands about the same distance to the lower right of the Moon.




Moon, Antares, Saturn

Sat, 18 Mar 2017 05:00:00 +0000

Many of the gods and goddesses of the ancient world weren’t very nice. They lied, they cheated, they stole, and they even killed. And many of these actions were aimed at their own families.

Consider the Greek god Kronos, who in Rome was known as Saturn. He was the father of an entire race of gods — the gods of Olympus. But to protect himself from his offspring, he swallowed them whole as soon as they were born — except for one.

According to the story, Kronos was the ruler of the gods known as the Titans. His parents had foretold that one of his children would defeat him. So each time his wife, Rhea, gave birth to a new baby, Kronos swallowed it.

Rhea wasn’t happy with that arrangement, though, so she tricked him. She hid her son Zeus in a cave. And — perhaps showing why you shouldn’t gobble your food — she gave Kronos a stone wrapped in a blanket.

When Zeus grew up, he drugged his father, forcing him to regurgitate his now-grown-up children. They ganged up and waged war against the Titans. They won, and imprisoned the Titans in a pit at the edge of the world. With Zeus as their leader, these brothers and sisters then ruled the world from Olympus.

The planet Saturn was named in honor of the god. And it’s in good view early tomorrow. It looks like a bright star to the lower left of the Moon at first light. And the bright star Antares is about the same distance to the lower right of the Moon.

Tomorrow: springtime.

Script by Damond Benningfield

StarDate: 
Saturday, March 18, 2017
Teaser: 
A planet with a nasty back story



Venus and Mercury

Fri, 17 Mar 2017 06:00:00 +0000

The Sun’s two closest planets are staging a switcheroo. Mercury is climbing higher into the evening sky, while Venus is dropping out of the sky. Venus is the brilliant “evening star,” with much fainter Mercury close to its lower left tonight.




Venus and Mercury

Fri, 17 Mar 2017 05:00:00 +0000

The Sun’s two closest planets are staging a switcheroo this month. Mercury is climbing higher into the evening sky, while Venus is dropping out of the evening sky. And if you look at just the right time, you can see them standing almost side by side the next few evenings.

Mercury is the closest planet to the Sun. Since Earth is the third planet out, Mercury has a limited range of motion across our sky, so the little planet rarely climbs into really good view. At best, it’s visible for a little while before sunrise or after sunset, quite low above the horizon.

Mercury passed behind the Sun earlier this month. Now, it’s moving away from the Sun, so it’s climbing into the evening sky. In fact, this is its best evening appearance for the entire year. It’ll climb higher over the next few nights, making it easier to see.

Venus is the second planet from the Sun. It’s getting ready to cross between Earth and Sun, so it’s dropping lower in the sky each evening — ready to move into the morning sky in about a week.

For now, though, look for Venus quite low in the west beginning about 15 minutes after sunset. It’s the “evening star,” so if you have a clear horizon, you can’t miss it. Tonight, much fainter Mercury is close to its lower left, but you probably need binoculars to pluck it from the twilight glow. The two worlds will stand side by side tomorrow night, with Mercury climbing away from Venus — and into better view — on succeeding nights.

 

Script by Damond Benningfield

StarDate: 
Friday, March 17, 2017
Teaser: 
A close pass in the evening sky



Giant Cannibal

Thu, 16 Mar 2017 06:00:00 +0000

Betelgeuse, the bright orange shoulder of Orion, is high in the south-southwest as night falls, above the hunter’s three-star belt. Recent research says that when Betelgeuse was younger, it might have swallowed a companion star as massive as the Sun.




Living Dangerously

Thu, 16 Mar 2017 05:00:00 +0000

A white dwarf star perches precariously close to a black hole in this artist's concept of 47 Tucanae X9, a binary system in the globular star cluster 47 Tucana. The white dwarf, which is the dead core of a star that was once like the Sun, is just 600,000 miles (1 million km) from the black hole, according to a team of astronomers that analyzed observations from Chandra X-Ray Observatory, a space telescope (a Chandra image is shown in the inset). It is the closest companion to a black hole yet discovered. The black hole's powerful gravity is pulling oxygen-rich gas from the white dwarf's surface. This material forms a disk around the black hole. Material in the disk eventually disappears into the black hole. 47 Tucana is about 15,000 light-years from Earth, in the southern constellation Tucana, the toucan. [NASA/CXC/M. Weiss; inset: NASA/CXC/University of Alberta/A. Bahramian et al.]

(image)



Giant Cannibal

Thu, 16 Mar 2017 05:00:00 +0000

Given the chance, a star can easily become a cannibal — a bigger star can swallow a smaller one. The star that gets eaten can leave its mark on the surviving star, though. Among other things, it can trigger an eruption or change the way the star rotates.

An example of that just may be found in Betelgeuse, the bright orange shoulder of Orion. It’s high in the south-southwest as night falls, above the hunter’s three-star belt.

When Betelgeuse was young, it was probably a few dozen times the diameter of the Sun. As it aged, though, changes in its core caused its outer layers to puff outward. Today, it’s many hundreds of times the Sun’s diameter.

And as Betelgeuse expanded, it just might have swallowed a companion star. That’s the conclusion reached by University of Texas astronomer Craig Wheeler after a team of his students used a computer model to study how Betelgeuse spins on its axis.

Wheeler says its rotation rate is unusually fast for a star of its size. The computer model shows that the star would spin that fast if it swallowed a Sun-sized companion. As the star spiraled in, it transferred its orbital motion to Betelgeuse’s outer layers, making the star spin faster.

A shell of gas surrounds Betelgeuse. It could have been expelled from the star when it swallowed the companion. Judging from the size and motion of the shell, that would have happened about a hundred thousand years ago — when Betelgeuse might have become a cannibal.

 

Script by Damond Benningfield

StarDate: 
Thursday, March 16, 2017
Teaser: 
A giant star becomes a cannibal



Quasars

Wed, 15 Mar 2017 06:00:00 +0000

Amateur telescopes reveal amazing sights. Perhaps the most amazing looks like an average star. It’s a maelstrom of gas around a massive black hole 2.5 billion light-years away. Known as 3C 273, it’s in the east at nightfall, above the brilliant planet Jupiter.




Quasars

Wed, 15 Mar 2017 05:00:00 +0000

Modern amateur telescopes reveal some amazing sights, from the colorful death throes of stars that are thousands of light-years away, to spiral galaxies millions of light-years away. Perhaps the most amazing sight of all, though, looks like an average star. But it’s really a maelstrom of gas around a supermassive black hole. It’s two and a half billion light-years from Earth, which means we see it as it looked two and a half billion years ago.

3C 273 is a quasar — one of the most powerful objects in the universe. It’s powered by a black hole that’s hundreds of millions of times as massive as the Sun. The black hole’s gravity pulls in gas, dust, and stars from the galaxy around it.

This material swirls around the black hole, forming a disk that’s about as wide as our solar system. Friction heats the material to millions of degrees, so it shines brighter than an entire galaxy of stars.

Magnetic fields direct some of the superhot gas in the disk into jets that shoot into space. The jets produce enormous amounts of radio waves. One of the jets aims at Earth, so we get a powerful blast of energy from it.

Astronomers have cataloged a couple of thousand quasars. Some are even more energetic than 3C 273. But they’re also farther away, so they don’t look as bright. That leaves 3C 273 as the most-distant object visible through most amateur telescopes. Right now, it’s in the east a couple of hours after night falls, well above the bright planet Jupiter.

 

Script by Damond Benningfield

 

StarDate: 
Wednesday, March 15, 2017
Teaser: 
Looking deep into the universe



Moon, Jupiter, and Spica

Tue, 14 Mar 2017 06:00:00 +0000

The dazzling planet Jupiter and the fainter star Spica rise almost even with the Moon this evening. All three objects are within the borders of the constellation Virgo.




Active Galaxies

Tue, 14 Mar 2017 05:00:00 +0000

The center of our home galaxy, the Milky Way, is pretty quiet. The supermassive black hole that lurks there isn't “feeding,” so it doesn't produce much energy.

That’s not the case for many other large galaxies, though. As many as a billion of them could be classified as active galaxies — their central black holes are generating enormous amounts of energy.

The black holes themselves aren’t actually producing the energy. Nothing comes out of a black hole, so it stays black. Instead, an active galaxy’s black hole — which is millions or billions of times the mass of the Sun — is pulling in big clouds of gas and dust, along with occasional stars.

As this material spirals toward the black hole, it forms a disk that’s heated to millions of degrees. At that temperature, the disk emits a lot of energy. Some of it is in the form of visible light, but much of it is in the ultraviolet and X-ray portions of the electromagnetic spectrum.

Some active galaxies also spew out long jets of gas that are moving at close to the speed of light. The jets produce radio waves, so the galaxy can shine brighter at radio wavelengths than any other form of energy; more about that tomorrow.

An active galaxy doesn’t stay active. Energy from the disk can blow away surrounding clouds of gas and dust. That deprives the black hole of food, so it shuts down. The black hole is still there, though, waiting to grab a passing star or gas cloud — once again turning its host into an active galaxy.

 

Script by Damond Benningfield

 

StarDate: 
Tuesday, March 14, 2017
Teaser: 
“Activating” the heart of a galaxy



Moon and Companions

Mon, 13 Mar 2017 06:00:00 +0000

Look for brilliant Jupiter rising below the almost-full Moon late this evening, with the bright star Spica close to the lower right of Jupiter. Through binoculars, Jupiter’s four big moons look like tiny stars arrayed near the giant planet.




Moon and Companions

Mon, 13 Mar 2017 05:00:00 +0000

One of the most exotic bodies in the solar system is Io, one of the large moons of Jupiter. It’s covered by hundreds of active volcanoes — more than any other body in the solar system. Their molten rock and volcanic gases make Io look like a scarred apricot.

Io is so active because of a gravitational tug-of-war between Jupiter and its other large moons.

The same side of Io always faces Jupiter, just as the same side of our moon always faces Earth. But as Jupiter’s other moons move past Io, they tug at it, trying to turn it around. That creates tides in Io’s crust. While the highest tides in Earth’s oceans are about 50 feet high, the tides in Io’s solid surface are more than 300 feet high. All of that energy melts some of the rock in Io’s interior, which then pushes its way to the surface.

At the surface, the molten rock bubbles up through cracks in the crust, sometimes building broad volcanic mountains.

Some of the volcanoes produce giant plumes of ash and gas, including the most prominent volcano of them all, known as Pele — a red-and-black bull’s-eye that’s hundreds of miles across. And the plumes extend far into space, creating a fat “doughnut” of gas that encircles Jupiter.

Look for brilliant Jupiter rising below our Moon late this evening, with the bright star Spica close to the lower right of Jupiter. Through binoculars, Io and Jupiter’s three other big moons look like tiny stars arrayed near the giant planet.

 

Script by Damond Benningfield

 

StarDate: 
Monday, March 13, 2017
Teaser: 
Heating up a Jovian moon



Bright Nights

Sun, 12 Mar 2017 06:17:17 +0000

The cities of Florida glow brilliantly in this 2012 view from the International Space Station. From the ground, the light sources blot out the view of the night sky. New LED streetlights can help reduce the glare, although those with bluer colors can make things worse. [NASA/JSC]

(image)



Darker Skies

Sun, 12 Mar 2017 06:00:00 +0000

Bright Nights The cities of Florida glow brilliantly in this 2012 view from the International Space Station. From the ground, the light sources blot out the view of the night sky. New LED streetlights can help reduce the glare, although those with bluer colors can make things worse. [NASA/JSC] A big light pollutes the sky tonight: the full Moon. Its glare blocks faint stars from view. But the Moon is so beautiful that it’s worth a little inconvenience — and besides, there’s not a thing we can do to change it. But we can change other sources of light pollution — the glow of civilization. The International Dark Sky Association says that because of that glow, 99 percent of the American population lives under light-polluted skies. And new light fixtures have the potential to make the problem worse. Many cities have been switching to LEDs for their streetlights. They last longer than older technologies, and they use less energy. The problem, though, is that most LEDs produce a lot of blue light. A recent report by the American Medical Association says that blue light scatters inside the eye, clouding your vision. It can also interfere with sleeping patterns. And, in fact, some cities that installed LED lights have had complaints from the neighbors. Blue light also scatters more in the sky; that’s why the daytime sky is blue. So blue light shining into the sky makes it harder to see the stars. Fortunately, though, newer LEDs are available in warmer colors than older models. With less blue light, there are fewer problems for residents. Phoenix decided to install almost a hundred thousand of these fixtures, and a city in California replaced its blue LEDs with the warmer ones. That makes it easier to sleep, drive — and enjoy a dark night sky.   Script by Damond Benningfield  Keywords: Light PollutionStargazing and SkywatchingStarDate: Sunday, March 12, 2017Teaser: A way to darken the night sky [...]



Darker Skies

Sun, 12 Mar 2017 06:00:00 +0000

A big light pollutes the sky tonight: the full Moon. Its glare blocks faint stars from view. But the Moon is so beautiful that it’s worth a little inconvenience. And besides, there’s not a thing we can do to change it.




Daylight Saving Time

Sat, 11 Mar 2017 06:00:00 +0000

We generally think of “springing forward” as a good thing. It suggests getting ahead — in a race, in a job, or in the progress of a civilization. Most of us in the United States will “spring forward” tonight, with the return of Daylight Saving Time. Whether that’s good or bad depends on your perspective. Some enjoy the extra hour of sunlight that’s added between the end of the work day and sunset. Others don’t enjoy having to leave for work or school when it’s still dark outside. The idea of springing forward during the months of more daylight hours caught on during World War I, with the United States adopting it in 1918. It lasted less than a year, but was reinstated during World War II. After the war, individual states were free to use Daylight Saving Time or not, for any part of the year they chose. It was standardized in 1966, and since then it’s been extended to take up a greater chunk of the year. The rationale for the modern version of Daylight Saving Time is that people tend to use less energy during the dark early morning than they do after darkness falls in the evening. So the idea is that extending daylight by an hour in the evening cuts down on energy use. Study results are mixed, but most do show a small savings. For now, just remember to set your clocks forward at 2 a.m. local time — an hour that you’ll get back when Daylight Saving Time ends and we “fall back” in November. Tomorrow: making the night sky darker.   Script by Damond Benningfield Keywords: Historical EventsTimekeeping and CalendarsWorld War IIStarDate: Saturday, March 11, 2017Teaser: Springing into a new time[...]



Daylight Saving Time

Sat, 11 Mar 2017 06:00:00 +0000

Most of the United States will “spring forward” tonight with the return of Daylight Saving Time at 2 a.m. local time. The U.S. first observed DST during World War I. It was dropped at war’s end, reinstated during World War II, and standardized in 1966.