StarDate

StarDate Online - Your guide to the universe

  • Early Light

    Some of the earliest galaxies were small, faint “puffballs” that nonetheless contained many hot, bright stars. And astronomers at the University of Texas at Austin are using light from those galaxies to learn about a key era in the universe’s evolution.

    A few hundred thousand years after the Big Bang, protons and electrons began linking up to make hydrogen atoms. The atoms had no electric charge, so they emitted no energy. The first stars and galaxies began to form then, but they were embedded within this “fog” of neutral gas — an epoch known as the Dark Ages.

    By a billion years after the Big Bang, though, the gas in the early galaxies had been “reionized” — the atoms were split apart by light from hot stars inside the galaxies.

    One tool for studying this process is the galaxies themselves. After the hydrogen atoms were split apart, some of them linked back up. When they did, they emitted a wavelength of light known as lyman alpha. It can be very bright, but it’s easily blocked by neutral hydrogen.

    Because they’re from the early universe, the galaxies are billions of light-years away. That means their light has to pass through a lot of hydrogen on its way to Earth. If the hydrogen has been ionized, the lyman alpha passes through easily. If not, then the light is blocked. So by measuring light from galaxies at different distances, the Texas astronomers hope to find out when the universe became reionized — ending the cosmic dark ages.

     

    Script by Damond Benningfield

    StarDate: 
    Friday, December 15, 2017
    Teaser: 
    Looking for “fog” in the early universe
  • Horsehead Nebula

    A cloud of cosmic gas and dust known as the Horsehead Nebula stands just below Orion’s Belt, a line of three bright stars that rises almost straight up from the southeastern horizon by 8 p.m. The Horsehead is visible in fairly small telescopes.

  • Colorful Demise

    A dying star surrounds itself with a colorful bubble of gas and dust in this recently released image from the XMM-Newton X-ray telescope in space. The bubble, known as the Crescent Nebula, consists of material blown off the outer layers of the dying star, which is many times more massive than the Sun. The blue shows where strong winds of charged particles have overtaken a shell of gas that was expelled about 200,000 years ago. This collision heats the shell, producing X-rays. Green shows oxygen atoms, where the star's wind is interacting with interstellar gas. The star is about 5,000 light-years away, in the constellation Cygnus. It probably will explode as a supernova, creating a new and brighter bubble. [ESA/XMM-Newton, J. Toalá & D. Goldman]

  • More Moon and Companions

    A bright arrow lines up in the south and southeast at dawn tomorrow. The crescent Moon forms the arrow’s feathers, with the shaft outlined by the equally spaced planets Jupiter and Mars, to the upper right of the Moon. The star Spica forms the arrow’s tip.

    Spacecraft have successfully visited the Moon and the two planets — dozens to the Moon, a couple of dozen to Mars, and almost 10 to Jupiter.

    Spica, on the other hand, is a different story. It’s about 250 light-years away — millions of times farther than Mars and Jupiter. At that distance, it would take millions of years for a conventional spacecraft to reach Spica. In fact, it would take hundreds of thousands of years to reach even the closest star system.

    That doesn’t mean that no one is trying to get there, though. A project called Breakthrough Starshot is working on plans to send a postage-stamp-sized craft to the Alpha Centauri system, our closest stellar neighbors. Although tiny, the craft would carry a camera, a radio transmitter, and other key equipment.

    The project launched some test probes in July. They remained in Earth orbit, attached to larger satellites. They consisted of single circuit boards that measured about an inch-and-a-half on each side. They carried their own power systems, transmitters, solar panels, and sensors.

    Known as Sprites, they mark a beginning in the effort to leave our own solar system — and take the first big step toward the stars.

     

    Script by Damond Benningfield

    StarDate: 
    Thursday, December 14, 2017
    Teaser: 
    Stepping toward the stars
  • More Moon and Companions

    A bright arrow lines up in the south and southeast at dawn tomorrow. The crescent Moon forms the arrow’s feathers, with the shaft outlined by the equally spaced planets Jupiter and Mars, to the upper right of the Moon. The star Spica is the arrow’s tip.

  • Moon and Companions

    A beautiful lineup stretches across the southeastern quadrant of the sky at first light tomorrow. It’s anchored by the crescent Moon and the nearby planet Jupiter, which looks like a brilliant star. The much-fainter planet Mars stands to their upper right, with the star Spica farther along the same line.

    The Moon today is an airless world. Its only atmosphere is a few atoms, most of which were captured from the solar wind. In the distant past, though, it might have had a much thicker atmosphere — one that came from inside the Moon.

    Recent research says the atmosphere was generated more than three billion years ago, when giant asteroids pummeled the lunar surface. They punched holes in the lunar crust. Molten rock oozed to the surface, creating dark volcanic plains.

    This process also released a lot of gas, including water vapor. The study says these gases formed an atmosphere that was at its densest about three and a half billion years ago. At that time, it was about half again as thick as the atmosphere of present-day Mars.

    Because the Moon’s gravity is weak, though, most of the air leaked out into space. But some of the watermight have made its way to the Moon’s poles, where it froze inside deep craters. Those deposits could still be there, forming the layers of ice detected by orbiting spacecraft. One day, they might provide drinking water and rocket fuel for colonists — sustaining human explorers with wisps of an ancient atmosphere.

     

    Script by Damond Benningfield

    StarDate: 
    Wednesday, December 13, 2017
    Teaser: 
    Gassing up a lunar atmosphere
  • Moon and Companions

    The Moon and the planet Jupiter, which looks like a brilliant star, anchor a beautiful lineup in the southeastern sky at first light tomorrow. The much-fainter planet Mars stands to their upper right, with the star Spica farther along the same line.

  • Moon and Mars

    Mars and the Moon are both quite dry. But they do contain sources of water. And some recent studies have found evidence of even more water.

    Scientists studied volcanic deposits on the lunar surface that contain tiny glass beads. Similar beads were brought to Earth by Apollo astronauts. Analysis showed that the beads contained high concentrations of water.

    And using observations made by a satellite from India, the researchers found evidence of water in volcanic deposits scattered across the Moon. The materials probably came from the Moon’s mantle — the layer below its crust. That suggests that the mantle could hold a lot of water.

    Other researchers recently found evidence for more water on Mars in observations made a decade ago. The scientists developed a technique that improved the quality of those observations. The new analysis revealed a lot of hydrogen wafting above large areas around the equator. The hydrogen could be an indication that large amounts of water ice are buried beneath the surface.

    Ice had already been found beneath the surface at high latitudes. But water at the equator wasn’t expected. The scientists still have a lot of work to do, though, to confirm the new analysis.

    Mars and the Moon are part of a beautiful quartet in tomorrow’s pre-dawn sky. Mars stands close below the Moon, with the star Spica to the right of the Moon. The brilliant planet Jupiter perches to the lower left. More about this lineup tomorrow.

     

    Script by Damond Benningfield

    StarDate: 
    Tuesday, December 12, 2017
    Teaser: 
    More water on two nearby worlds
  • Moon and Mars

    Mars and the Moon are part of a beautiful quartet in tomorrow’s pre-dawn sky. Mars will stand close below the Moon, with the star Spica to the right of the Moon. The brilliant planet Jupiter perches below them.

  • Phaethon

    One of the strongest meteor showers of the year, the Geminids, will be at its best on Wednesday night. The shower should sprinkle dozens of meteors into the sky per hour. And the Moon won’t interfere with the fireworks, so it should be a pretty good show.

    Most meteor showers form when Earth sweeps up streams of particles shed by an icy comet. But the Geminids were the first meteor shower known to be spawned instead by a rocky asteroid.

    Skywatchers have seen the Geminids for more than a century. But the shower’s source wasn’t discovered until 1983, by a small space telescope. The asteroid’s orbit around the Sun matches that of the Geminid meteor stream.

    The three-mile-long asteroid leads a rough life. It orbits the Sun once every 17 months. It follows a highly elliptical path, so it both freezes and fries. At its farthest from the Sun, it’s outside the chilly orbit of Mars. When it’s closest to the Sun, though, the asteroid skirts well inside the orbit of Mercury. At that range, its surface temperature soars to more than a thousand degrees Fahrenheit. Because of that Sun-skimming flight, the asteroid was named Phaethon, after a son of the Greek Sun god Helios.

    Phaethon may be a former comet that has exhausted its supply of ice. Or it could be a chip off a bigger asteroid.

    Phaethon passed just 6.4 million miles from Earth on Saturday. Up next, the asteroid’s offspring will reach its peak — the beautiful Geminid meteor shower.

     

    Script by Ken Croswell

    StarDate: 
    Monday, December 11, 2017
    Teaser: 
    A meteor shower with a difference
  • Geminids

    One of the strongest meteor showers of the year, the Geminids, should be at its best on Wednesday night. The shower may sprinkle dozens of meteors into the sky per hour. The Moon won’t interfere with the fireworks, so it should be a good show.

  • Orion Rising

    Orion, one of the brightest and most beautiful constellations, rises to evening prominence in December. This view shows its appearance around 8 p.m. local time on December 10. By two weeks later, it will stand at that same height an hour earlier. [Tim Jones]

  • Orion Rising

    The most visually impressive constellation in all the night sky climbs to prominence on December nights. It’s a sight you don’t want to miss.

    Orion the hunter clears the eastern horizon by about 8 p.m. And it’s easy to find. Look for its “belt” of three moderately bright stars, which aims straight up into the sky as the constellation rises. It’s flanked by Orion’s brightest stars — orange Betelgeuse to the left, and blue-white Rigel to the right. And two other bright stars team up with them to complete a rectangle around the belt.

    All seven of the stars that mark the rectangle and the belt look bright because they really are bright. They’re all supergiants — stars that are much bigger and heavier than the Sun, and tens of thousands of times brighter.

    Such stars blaze through their nuclear fuel in a hurry, so they live short lives — tens of millions of years, compared to billions of years for a star like the Sun. And when such a star expires, it blasts itself to bits as a supernova.

    Even more giants are being born in the Orion Nebula. It’s in Orion’s sword, which extends to the lower right of the belt. The nebula looks like a faint, fuzzy star. But it’s really a stellar nursery that’s given birth to thousands of stars, with many more still being incubated. That includes several supergiants, which light up the surrounding gas and dust. They, too, will blast themselves apart — briefly adding to the luster of this amazing constellation.

     

    Script by Damond Benningfield

    StarDate: 
    Sunday, December 10, 2017
    Teaser: 
    The return of the hunter
  • Orion Rising

    Orion the hunter clears the eastern horizon by about 8 p.m. Look for its belt of three moderately bright stars, which aims straight up into the sky as Orion rises. It’s flanked by Orion’s brightest stars: Betelgeuse to the left, Rigel to the right.

  • Life of the Sun

    With winter approaching, the Sun can seem small and remote for those at far-northern latitudes. Its feeble light doesn’t do much to warm up the shorter days.

    In the distant future, though, that won’t be a problem. The Sun will be much brighter than it is now, so it’ll keep Earth toasty warm all the time. In fact, within a billion years or so, the Sun will get so warm that it’ll boil away Earth’s oceans and air, turning our planet into a cosmic cinder.

    The Sun is constantly evolving. It’s “fusing” the hydrogen in its core to make helium. That process converts about four million tons of matter to energy every second, which is what makes the Sun shine.

    As more hydrogen is fused to make helium, the core gets smaller and hotter. Radiation from the hotter core pushes on the Sun’s outer layers, causing them to puff up, making our star even brighter. Astronomers estimate that it’s about 30 percent brighter today than when it was born four and a half billion years ago. And every hundred million years, it gets another one percent brighter still. So in a billion years, Earth will get so much solar energy that it won’t be habitable.

    In about five billion years, the Sun will enter the next phase of life. It’ll puff up to giant proportions. Then it’ll start burning the helium in its core to make carbon and oxygen, and get bigger still. Finally, it will expel its outer layers, leaving only its hot but dead core, shining feebly through the cosmic night.

     

    Script by Damond Benningfield

    StarDate: 
    Saturday, December 9, 2017
    Teaser: 
    Our constantly changing Sun
  • Last-Quarter Moon

    The Moon will reach its “last-quarter” phase at 1:51 a.m. CST tomorrow, when it lines up at a right angle to the line between Earth and the Sun. Sunlight will illuminate half of the lunar surface, with that fraction growing smaller over the coming week.

  • Doomed Giant

    A giant planet that’s orbiting a Sun-like star appears to be in its final days. A recent study says the planet could disintegrate and fall into its sun in about three million years.

    The system is known as WASP-12. It’s about 870 light-years away. The star is a bit bigger, hotter, and heavier than the Sun. And the planet, WASP-12b, is similar to Jupiter, the giant of our own solar system — a big ball of gas, perhaps wrapped around a solid core.

    The planet and star are quite close together — just a quarter of the distance between Earth and the Sun. At that range, the side of the planet that faces the star sizzles at thousands of degrees. Some of the planet’s atmosphere is being blown out into space by the star’s wind and radiation. And the planet is warped by the star’s gravitational pull, so it’s shaped a bit like an egg, with the tapered end facing the star.

    The study says the planet appears to be spiraling closer to the star. The star’s gravity could soon rip the planet apart. And the remains could fall onto the star in about 3.2 million years — ending the life of a planetary giant.

    WASP-12 is too faint to see with the eye alone. But its constellation, Auriga the charioteer, is in good view on December nights. Right now, it’s low in the east-northeast at nightfall. It’s easy to find because its leading light, yellow-orange Capella, is one of the brightest stars in all the night sky.

     

    Script by Damond Benningfield

    StarDate: 
    Friday, December 8, 2017
    Teaser: 
    The final days of a giant planet
  • More Moon and Regulus

    Regulus, which marks the heart of the lion, crouches to the right of the Moon at first light tomorrow. Regulus is one of the brightest stars in northern skies, so it’s hard to miss.

  • Moon and Regulus

    Most of the stars that fill the Milky Way galaxy are in the prime of life. They are steadily “fusing” together hydrogen atoms in their cores to make helium, the next-heaviest element. In astronomical jargon, stars in that phase of life are on the main sequence — a description that comes from a simple plot of a star’s brightness and temperature.

    When you plot a lot of stars, most of them lie along the same diagonal line — the main sequence. Hot, bright stars are at one corner of the plot, with cool, faint stars at the opposite corner.

    One prominent star that’s on the main sequence is Regulus, the brightest star of Leo, the lion. It follows the Moon across the sky after they rise late this evening.

    Regulus actually consists of two stars that are locked in a tight orbit around each other. One of the stars is well past the prime of life. But the other — the one that’s visible to the eye alone — is in its prime.

    Regulus is on the bright, hot side of the sequence — it’s hundreds of times brighter than the Sun, and thousands of degrees hotter. And that tells astronomers a lot about the star. It’s several times the Sun’s mass, for example. And since heavier stars consume their hydrogen at a rapid rate, Regulus will spend a much shorter time on the main sequence than the Sun will.

    So astronomers can learn a lot about what’s going on inside a star, how long it will live, and more — just by plotting the star’s place on the main sequence.

     

    Script by Damond Benningfield

    StarDate: 
    Thursday, December 7, 2017
    Teaser: 
    A star in the prime of life
  • Moon and Regulus

    Regulus, the brightest star of the constellation Leo, the celestial lion, follows the Moon across the sky after they rise late this evening.

  • Rock Hunting

    A meteorite sits on the Antarctic ice while members of a scientific expedition prepare to bag it. Other meteorite hunters, part of a project called ANSMET, are deploying at two locations in Antarctica in early December to continue the search for these bits of cosmic debris. In four decades of searches, ANSMET has gathered more than 22,000 extraterrestrial samples, including some from the Moon and the planet Mars. [ANSMET/USAP]

  • Hunting Space Rocks II

    Rock hunters have been known to visit some tough environments to collect their treasures. But for the next few weeks, a group of scientists will be hunting rocks in perhaps the most extreme environment on the planet: the Antarctic ice. The researchers are hunting meteorites — chips of rock from asteroids and other solar system bodies.

    A project known as ANSMET has been visiting Antarctica every southern summer since the 1970s. It’s collected more than 22,000 space rocks.

    The scientists journey to McMurdo Station, the largest settlement on the continent. They survey their planned hunting grounds from the air to confirm that the areas are safe and productive. Then they’re ferried to the ice by small aircraft. They spend weeks on the ice, living in tents.

    When the weather conditions are good, they traverse the ice on snowmobiles. When they find a likely meteorite, they give it an ID number, log its position with GPS, and take its picture. They then grab the specimen with a Teflon bag, making sure not to touch it with their fingers or tools — a precaution against possible contamination.

    At the end of the season, the rocks are shipped to a lab at Johnson Space Center for cataloging and preliminary analysis. Samples are then sent to scientists around the world. Eventually, all the samples are sent to the Smithsonian for permanent storage and curation — rocks from beyond Earth found in one of the most extreme environments on Earth.

     

    Script by Damond Benningfield

    StarDate: 
    Wednesday, December 6, 2017
    Teaser: 
    Extreme rock hunting
  • Gemini’s Twins

    Many cultures have seen two human figures in the stars of Gemini. Twin streamers of stars extend from Castor and Pollux, the bright “twin” stars that give Gemini its name. They line up directly above the Moon this evening.

  • Hunting Space Rocks

    Mount Cecily and Mount Raymond are two fairly unremarkable peaks in the Grosvenor Mountains of Antarctica. But something remarkable litters the ice at their bases: rocks from outer space. In fact, a team of scientists will be spending the next couple of months there, gathering up the meteorites for later study. At the same time, another group will be looking for meteorites on an ice field a few hundred miles away.

    The scientists are part of ANSMET — the Antarctic Search for Meteorites. It’s been sending teams to the Antarctic for more than 40 years. They’ve gathered more than 22,000 meteorites. Most are chips off the surfaces of asteroids. But many are pieces of the Moon and the planet Mars.

    Antarctica is a good site to hunt for these rocks for a couple of reasons. First, out on the open ice there are very few Earth rocks. That means there’s a good chance that any rocks sitting on the surface came from space.

    And second, the bases of mountains can expose meteorites that have been on Earth for a long time. As glaciers flow toward the edge of the continent, they ram into mountain ranges. Layers of ice that have been buried for thousands of years can be pushed to the surface. Strong, dry winds vaporize much of the ice, exposing rocks that had been entombed in the ice — including a high concentration of meteorites. In fact, that’s what makes the Grosvenor Mountains a good spot for hunting for rocks from beyond Earth.

    More about the search tomorrow.

     

    Script by Damond Benningfield

    StarDate: 
    Tuesday, December 5, 2017
    Teaser: 
    Rock hunting on ice
  • Lepus

    Lepus, the rabbit, hops across the evening sky this month, beneath the feet of Orion, the hunter. Since the rabbit was one of Orion’s favorite quarries, early skywatchers thought it fitting for hunter and prey to inhabit the same area of the sky.

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