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Jack Horkheimer: Star Gazer

Star Gazer is the world's only weekly television series on naked eye astronomy. Each weekly episode features selected objects for naked eye viewing for the following week. This video podcast contains the 10 most recent episodes of Jack Horkheimer: Star Gazer.

FaviconStar Gazers 1 Min. Dec. 30, 2013- Jan 5, 2013 13 Nov 2013, 4:10 pm

Here Comes The Sun

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FaviconStar Gazers 5 Min. Dec. 30, 2013- Jan 5, 2013 13 Nov 2013, 4:09 pm

Here Comes The Sun

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FaviconStar Gazers 1 Min. Dec. 23-29, 2013 13 Nov 2013, 4:08 pm

Bye-Bye Venus,Good-bye And Celebrate The New Year With The New Year's Eve Star

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FaviconStar Gazers 5 Min. Dec. 23-29, 2013 13 Nov 2013, 4:06 pm

Bye-Bye Venus,Good-bye And Celebrate The New Year With The New Year's Eve Star

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FaviconStar Gazers 1 Min. Dec. 16-22, 2013 13 Nov 2013, 4:03 pm

Off To The Races With Venus And Jupiter

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Science @ NASA Feature Stories Podcast

The mission of Science@NASA is to help the public understand how exciting NASA research is and to help NASA scientists fulfill their outreach responsibilities.

FaviconGeminid Meteors Defy Explanation 9 Dec 2010, 3:00 pm

The annual Geminid meteor shower peaks this year on Dec. 13th and 14th. Researchers don't fully understand the Geminids, and new measurements make it more mysterious than ever.

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Favicon"Arsenic-Bug" Redefines Life as We Know It 2 Dec 2010, 3:00 pm

NASA-supported researchers have discovered the first known microorganism on Earth able to thrive and reproduce using the toxic chemical arsenic. The microorganism, which lives in California's Mono Lake, substitutes arsenic for phosphorus in the backbone of its DNA.

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FaviconAlien Comets Invade the Solar System 23 Nov 2010, 3:00 pm

Some of the comets in our Solar System probably came from other stars, according to new research by NASA-supported scientists. Studying these 'alien' comets, they say, could reveal new information about stellar systems far, far away.

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FaviconHubble Observes Possible Asteroid Collision 13 Oct 2010, 2:00 am

NASA's Hubble Space Telescope has captured rare images of a suspected asteroid collision. The snapshots show a bizarre X-shaped object at the head of a comet-like trail of material. Their findings will be published in the Oct. 14th issue of Nature.

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StarDate

FaviconInterferometry III 10 Feb 2016, 1:00 am

Combining the views from two or more optical telescopes provides a sharper image of the heavens. But it requires extreme precision to make it work.

The technique is known as interferometry. Light waves from the individual telescopes “interfere” with each other when they’re combined. The way they interfere allows astronomers to produce images of astronomical objects.

Interferometry’s advantage is that the combined telescopes see the universe as clearly as a much bigger single telescope. And the farther apart they are, the sharper their vision.

For an interferometer to work, the light from all the telescopes must come together at precisely the same time. That’s a complicated task. A star’s light reaches each telescope at a slightly different time. And the telescopes will be placed at different distances from the instruments that combine and analyze their light. Those differences add up to a few billionths of a second — but that’s enough to ruin the view.

One way to compensate is to send the light from each telescope through a series of vacuum tubes and mirrors. The light from a closer telescope follows a longer path, making sure it reaches the instrument at the same time as light from a more-distant telescope.

As more telescopes are added, the view improves — but making it work gets tougher. We’ll talk about an array that’s designed for 10 telescopes — the Magdalena Ridge Observatory Interferometer in New Mexico — tomorrow.


Script by Damond Benningfield


For more skywatching tips, astronomy news, and much more, read StarDate magazine.
The one constant in the Universe: StarDate magazine

FaviconInterferometry II 9 Feb 2016, 1:00 am

HL Tauri is like a newborn version of our own solar system, with a Sun-like star surrounded by a disk of gas and dust.

HL TauriALMA view of HL TauriA remarkable image of the system reveals bright rings and dark gaps within the disk — sculpted by planets. The planets grow by sweeping up the gas and dust around them, clearing out gaps. And the planets’ gravity causes the remaining gas and dust to concentrate in the bright rings.

This image of HL Tauri was made with a technique known as interferometry. It combines the light from two or more telescopes to create images that are as sharp as those made by a single telescope that’s as big as the distance between the individual telescopes.

ALMA telescopeMany of the ALMA dishes shine beneath the Magellanic Clouds, two companion galaxies to the Milky Way [ESO/Christoph Malin]The picture of HL Tauri, for example, was taken by ALMA, a radio telescope in Chile. It consists of dozens of individual radio dishes that can be spread up to about 10 miles apart. That provides images that are as sharp as the view from a single radio dish 10 miles wide, but at a fraction of the cost.

Making an interferometer work isn’t easy, though. For example, the observations from the individual telescopes have to be precisely synchronized. If the timing is off by a millionth of a second, the observations are ruined. In most radio interferometers, the observations from each dish are recorded and later combined with a powerful computer.

A few interferometers look at visible light, which is even trickier than radio waves. We’ll have more about that tomorrow.


Script by Damond Benningfield


For more skywatching tips, astronomy news, and much more, read StarDate magazine.
The one constant in the Universe: StarDate magazine

FaviconInterferometry 8 Feb 2016, 1:00 am

One of the monsters of the Milky Way climbs across the south on winter nights. Betelgeuse, the bright orange shoulder of Orion, is high in the southeast at nightfall, and due south a couple of hours later.

The star is so huge that if it took the Sun’s place in our own solar system, it would engulf everything out to Jupiter, the fifth planet.

Betelgeuse was the first star other than the Sun to have its size measured. But despite its great girth, it took an entirely new technique, known as interferometry, to make that measurement.

1920 interferometry experimentDiagram shows how the 1920 experiment worked [Mount Wilson Observatory]Two astronomers did so back in 1920. They used a new telescope at Mount Wilson Observatory in California — the largest in the world. But they added something extra — a pair of small mirrors attached to a wide frame that was mounted atop the telescope. The mirrors were about 20 feet apart. They gathered the light from Betelgeuse, and directed it to the telescope’s main mirror.

The extended mirrors provided two separate beams of light from the star, which were then combined. That combined view was as sharp as the view from a single mirror as wide as the separation between the two small mirrors. That allowed the astronomers to see Betelgeuse as a disk, not just a pinpoint. They measured the size of the disk at hundreds of times the diameter of the Sun — the first confirmation that stars could grow to such giant proportions.

Despite that early success, it took a while for interferometry to catch on. More about that tomorrow.


Script by Damond Benningfield

For more skywatching tips, astronomy news, and much more, read StarDate magazine.
The one constant in the Universe: StarDate magazine

FaviconFaint Neighbors 7 Feb 2016, 2:45 am

A tiny brown dwarf glows next to its stellar companion, Gliese 229, in this false-color image from Hubble Space Telescope. The brown dwarf, known as Gliese 229B, is a "failed star" -- an object that is more massive than a planet, but not massive enough to ignite nuclear fusion and shine as a true star. Gliese 229 is one of our closest stellar neighbors, at a distance of about 20 light-years. [NASA/JHU/Caltech]

Hubble Space Telescope view of the Gliese 229 system

Text ©2016 The University of Texas at Austin McDonald Observatory

For more skywatching tips, astronomy news, and much more, read StarDate magazine.
The one constant in the Universe: StarDate magazine

FaviconFaint Neighbors 7 Feb 2016, 1:00 am

The brightest star visible in Lepus, the rabbit, is a stunner. It’s more than 30,000 times brighter than the Sun, so it’s easily visible to the unaided eye even though it’s more than 2,000 light-years away.

The constellation’s closest star is less than 20 light-years away. Yet it’s so feeble that you need a telescope to see it. And it has a small companion that’s even fainter: a cool ember known as a brown dwarf.

Gliese 229 is smaller and less massive than the Sun, which is the key to its faintness. A lightweight star burns through the nuclear fuel in its core much more slowly than a heavy star. That generates much less energy, so there’s not much for the star to radiate into space.

The brown dwarf companion — Gliese 229B — probably doesn’t produce any energy in its core. It’s a few dozen times the mass of Jupiter, the largest planet in the solar system. That’s just not big enough to ignite nuclear fusion and allow it to shine as a true star.

Gliese 229B probably formed like its bigger companion, from the collapse of a cloud of gas and dust. The cloud split apart, producing two separate objects. But there wasn’t enough material in Gliese 229B’s part of the cloud to make a star. Instead, it made a faint cosmic ember — a brown dwarf.

Lepus hops below the feet of Orion, which is high in the sky at nightfall. The rabbit’s brightest star is easy to spot, but Gliese 229 remains invisible — a close neighbor hidden from sight.

 

Script by Damond Benningfield, Copyright 2015

For more skywatching tips, astronomy news, and much more, read StarDate magazine.
The one constant in the Universe: StarDate magazine

ESOcast HD

ESOcast is a video podcast series dedicated to bringing you the latest news and research from ESO, the European Southern Observatory. Here we explore the Universe's ultimate frontier with our host Doctor J, a.k.a. Dr. Joe Liske.

FaviconESOcast 81: Red Sprites 1 Feb 2016, 8:00 am

As night falls, telescopes at ESO's observatories are just starting the night’s observations. But all of a sudden a strange phenomenon appears in the distance. What could this be? Let’s take a closer look!

FaviconESOcast 80: Follow a Live Planet Hunt 15 Jan 2016, 11:00 am

And a unique new project will now allow members of the public to go behind the scenes and follow a planet hunt as it happens!

FaviconESOcast 79: 20 Years of Exoplanets 8 Dec 2015, 4:00 am

Not a single confirmed planet outside the Solar System had been detected before the year 1990. But, remarkably, we now know of thousands and have studied many in surprising detail.

FaviconESOcast 78: Airglow 4 Nov 2015, 5:00 am

ESO’s La Silla Observatory on a moonless night, deep in the Atacama Desert of Chile. It should be very dark -- but strange green and red colours can be seen to shimmer in the sky. What are these mysterious glows? And why do they seem to be getting more frequent? Find out more in this episode.

FaviconESOcast 77: Mysterious Ripples Found Racing Through Planet-forming Disc 7 Oct 2015, 1:00 pm

Images from ESO’s Very Large Telescope and the NASA/ESA Hubble Space Telescope have revealed unique and totally unexpected structures in the dusty disc around the star AU Microscopii. These fast-moving wave-like dust features are unlike anything ever observed, or even predicted, before now.

HD - NASA's Jet Propulsion Laboratory

High-definition (HD) videos from NASA's Jet Propulsion Laboratory feature the latest news on space and science findings from JPL and NASA. Topics include discoveries made by spacecraft studying planets in our solar system, including Mars, Saturn and our home planet, Earth. Missions also study stars and galaxies in our universe.

FaviconFlight Over Ceres 29 Jan 2016, 3:00 am



A colorful animation shows a simulated flight over the surface of dwarf planet Ceres, based on images from NASA's Dawn spacecraft.



FaviconWhat's Up - February 2016 28 Jan 2016, 3:00 am



Five morning planets, comet Catalina passes Polaris, and icy Uranus and icy Vesta meet near Valentine's Day.



FaviconWhat's Up - January 2016 1 Jan 2016, 3:00 am



What's Up for January? A meteor shower, a binocular comet, and the winter circle of stars!



FaviconCuriosity Rover Report (Dec. 15, 2015): First Visit to Martian Dunes 10 Dec 2015, 3:00 am



Curiosity performs the first investigation of active sand dunes on another planet. Studying the Bagnold Dunes on Mars will help scientists understand the physics of Martian dunes and how they move.



FaviconCeres Rotation and Occator Crater 8 Dec 2015, 3:00 am



Dwarf planet Ceres is shown in these false-color renderings, which highlight differences in surface materials.