Skywatch

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    Episode 91: Out for a Spin

    One of the strangest objects we know of is a neutron star, which forms upon the death of a star about twice the mass of the Sun. At the end of its life, the massive star collapses into a tiny object just 6-12 miles (10-20 km) in diameter. Because so much mass is crushed into such a small space, neutron stars are incredibly dense. A thimbleful of neutron star material weighs a hundred million tons. Neutron stars are often found spinning, and can emit X-rays as they spin. A recently discovered neutron star called XTE J1739-285 appears to be the fastest spinning neutron star known. It spins 1122 times every second.

  • Hubblewatch

    Episode 89: HubbleWatch for March 2007

    The Hubble Space Telescope has been watching a supernova in progress since its launch in 1990. The stellar explosion, which first appeared in 1987, is known as SN1987A. Hubble has observed over the years as the shockwave from the explosion slams into the rings of gas circling the dying star. This is astronomers' first close-up and personal view of the death of a massive star. "Hot Jupiters," huge gas planets located perilously close to their parent stars, appear to be scattered throughout our galaxy. One such planet is so close to its star that its atmosphere has puffed up from the heat and is boiling off into space. Hubble is helping astronomers get a glimpse at what that atmosphere is like. The New Horizons space probe, on its way to Pluto, recently swung by the planet Jupiter. The planet's gravity helped slingshot the probe deeper into space. But while it was there, New Horizons took pictures of the gas giant. Hubble took images of Jupiter at the same time, allowing scientists to compare and contrast pictures from both missions.

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    Episode 90: Got Supernovae?

    The universe is full of calcium ? the same substance that helps clot blood and fortifies bones. Calcium, in fact, is the fifth most common element on our planet. We know that elements like iron and sulfur come from the nuclear reactions in exploding stars. It turns out that these supernovae explosions also produce calcium. New X-ray observations taken at the XMM-Newton Observatory indicate that the universe has more calcium than previously thought, giving rise to new theories about the formation of elements and the role of supernovae in their creation.

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    Episode 88: First Light

    How did the universe come into being? To figure out where the universe came from and how it's evolving, we need to look at what was happening very early, right after the Big Bang. Scientists can look for "first light," the leftover glow from the Big Bang. The leftover heat is part of the microwave spectrum. Two earlier satellites, the Cosmic Background Explorer Satellite (COBE) and the Wilkinson Microwave Anisotropy Probe studied this "cosmic background radiation." The satellites were designed to be extremely sensitive to changes in temperature, and mapped the radiation throughout the sky. Now a new satellite, the European Space Agency's Planck probe, will examine that background radiation. Planck, set to launch in 2008, will map the sea of microwaves with a precision that was unattainable earlier

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    Episode 87: Planet Leaks Hydrogen

    A large planet, the size of Jupiter, orbits the star HD 209458. The planet, creatively called HD 209458b, has been studied extensively since its discovery in 1999. Its orbit periodically brings the planet between its star and us, allowing astronomers to detect it using a technique called spectroscopy. The planet's orbit is short, about 3.5 days, because the planet is very close to the parent star. Observations by Hubble found sodium, carbon and oxygen in the planet's atmosphere. Newer observations show that the star is heating up the outer atmosphere of HD 209458b so much that hydrogen is streaming off of it into space.

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    Episode 86: Lunar Eclipse

    The Earth will cast its shadow on the Moon on March 3, causing a lunar eclipse. Unlike solar eclipses, lunar eclipses are perfectly safe to watch, so grab a pair of binoculars and see how the Moon appears in the shade. The Moon should take on a strong reddish or orange tinge as it falls into the Earth's shadow.

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    Episode 84: New Horizons Visits Jupiter

    The New Horizons spacecraft is on its way to Pluto and will arrive in 2015. To speed things up as much as possible, the spacecraft is about to swing by Jupiter. Jupiter's gravity will give it a push that will boost its speed by 9,000 mph. While zooming by the giant planet, the probe will examine its cloudy atmosphere, moons and gigantic tail of charged particles that stretches as far back as the orbit of planet Saturn.

  • Hubblewatch

    Episode 85: HubbleWatch for February 2007

    An international team of astronomers has mapped out the dark matter in the universe for the first time. The map shows that normal matter seems to accumulate along the densest concentrations of the invisible substance. Hubble found a blizzard of particles in a dust disk around a young star, helping scientists understand the way planets eventually form from the clumping together of tiny particles. The particles are as fluffy as snowflakes and about 10 times larger than normal interstellar dust grains. Hubble's Advanced Camera for Surveys, Hubble's most prized instrument, shut down in January after an electrical fuse blew. The ACS had lived out its expected five year lifetime, but NASA is currently attempting to identify the precise cause of the problem and decide whether it would be safe to return ACS to operation. In the meantime, Hubble's three other instruments are operating normally. The servicing mission planned for 2008 would add new, more powerful instruments to the telescope.

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    Episode 83: Planet Hunting

    Astronomers are on the hunt for more planets in other star systems In December, the Europeans launched a satellite called COROT to look some more. COROT, which stands for "Convection Rotation and Planetary Transits," is designed to detect the faint dimming of light as a planet moves between the observatory and its home star. COROT will also look for seismic waves that cause ripples on stars, giving hints to the stars' structures and perhaps their masses and ages.

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    Episode 82: Moon Geysers

    The Cassini spacecraft has detected geysers in a most unusual place - on Saturn's icy moon, Enceladus. Cassini's images show plumes ejecting large amounts of particles at high speed. The geysers could resemble those in Yellowstone, except that they erupt with icy water. Scientists are excited by the find, suspecting that it could indicate reservoirs of water just meters below the moon's surface. Other moons in the solar system are known to have water, but those reservoirs are also thought to be covered by kilometers of ice.

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    Episode 81: Mapping Dark Matter

    Dark matter, the invisible substance that seems to make up most of the matter in the universe, remains a mystery. Astronomers think that mapping the presence of dark matter might help them understand it better. By combining observations from many telescopes, including Hubble, the Very Large Telescope in Chile, and a variety of radio and infrared telescopes, astronomers created a three-dimensional map of the distribution of dark matter in the universe. Interestingly, normal matter appears to accumulate along the densest concentration of dark matter.

  • Hubblewatch

    Episode 142: HubbleWatch for January 2008

    Hubble has found stars clusters where no star clusters should be -- cast adrift in the open space between galaxies. The clusters may give hints about the nature of the early universe. Scientists hit the jackpot with a remarkably lucky find - a double Einstein ring. A rare alignment of a trio of galaxies distorts light, forming a duo of rings that could reveal information about a host of galactic mysteries. A new book opens the universe of modern telescope images to the blind. "Touch the Invisible Sky" combines Braille with embossed pictures to show visually impaired students what astronomical objects look like in different types of radiation, or the "invisible" light referred to in the title.

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    Episode 80: Space Weather

    Weather predictions in space are even trickier than forecasts on Earth. Space weather forecasting largely deals with the pattern of the Sun's activity, or solar cycle. Scientists monitor Sun activity by counting sunspots. These spots are associated with magnetic storms and the ejection of huge plasma plumes from the Sun. Plasma plumes take about three days to reach Earth. Space weather is important in part because of its effect on satellites. A strong solar cycle can expand the Earth's atmosphere, slowing down orbiting satellites - including the Hubble Space Telescope.

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    Episode 78: Water on the Moon?

    Talk of building bases on the Moon has revived interest in the lunar environment. Scientists are trying to determine whether there are any sources of water on the Moon. Those sources would be ice, probably located in craters. Unfortunately, the prospects don't look good. Radar observations of Shackleton Crater at the Moon's south pole have shown no signs of water. Scientists plan to keep looking.

  • Hubblewatch

    Episode 79: HubbleWatch for January 2007

    As we begin the year 2007, it's time for a look back at Hubble's accomplishments in 2006. Join us for Hubble highlights on dark matter and dark energy, planetary discoveries, and the news on the mission to prolong Hubble's life.

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    Episode 77: Meet the Neighbors

    The population of known stars in our stellar neighborhood ? within about 33 light years ? has increased by 16 percent in six years. That?s not because the number of stars has increased, but because astronomers are working hard to find these stars, conducting a kind of cosmic census of our region of space. By finding all the stars in our stellar neighborhood, scientists identify possible targets for planetary systems.

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    Episode 76: What Causes Seasons?

    On Jan. 4, 2006, the Earth reached perihelion, or the closest point in its elliptical orbit to the Sun. Yet the Northern Hemisphere isn't exactly toasty in the beginning of January. What gives? It's actually the tilt of the Earth that causes the changes in the seasons, not the proximity of the Earth to the Sun. Right now the Northern Hemisphere is tilted away from the Sun, meaning less sunlight hits the surface. The less sunlight, the colder it is. How sunlight affects the Earth depends on where it hits. Ground heats more quickly than water, so continents react more swiftly to changes in the amount of sunlight than oceans.

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    Episode 75: Hot Comets?

    Comets travel to Earth and the Sun on orbits that originate in the far reaches of our solar system. From observations and samples collected from a few comets, it seemed that the icy realm far beyond the orbit of Pluto was their birthplace. Comets have been called "dirty snowballs" because they?re composed mostly of ice and some grainy material. The results emerging from the Stardust mission, which snatched a material sample from an actual comet, suggests that some of comet material formed in an intensely hot environment. Scientists believe comets, planets, asteroids and other objects formed from the disk of gas and dust that collected around the Sun. Perhaps the Sun spewed jets of hot material to the far reaches of the disk, giving the comets their blistering background.

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    Episode 74: Next Space Telescope Delayed

    NASA plans to delay the launch of the next space telescope, the James Webb Space Telescope, until 2013. JWST is the successor to the Hubble Space Telescope, but differs from it in many ways. JWST will not be serviceable - instead, it will orbit a million miles from Earth, and its goal will be to see the first galaxies that formed in the early universe. Its instruments are designed to see primarily in infrared, perceived by humans as heat.

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    Episode 72: A Light Echo

    In 2002, an ordinary star in the night sky suddenly flashed to a brightness 600,000 times that of the Sun. No one knows why the eruption occurred, but since then, astronomers have monitored the star, known as V838 Monocerotis (V838 Mon), with the Hubble Space Telescope. An interesting nebula has formed and appears to be expanding around the central object. The nebula isn't really expanding though. The light from the intense brightening of the star is traveling through space, reflecting as it goes off the dust surrounding the star. This effect is called a "light echo." It's something like listening to a shout in the mountains as it reflects off of various surfaces.