Deep Astronomy

  • January 5, 2014

    Streaming the 223rd AAS Meeting

    by Tony Darnell

    At this year's AAS meeting, I have plans to step up our live-streaming game. If you want to see all streams that we're planning (schedule will follow) then bookmark this page and watch my Twitter feed for announcements.

    I want to emphasize that this is an experiment, so there will be lots of strangeness, and there are issues of copyright and privacy that I need to think about.  I'm primarily going to stream at the exhibit hall at our booth with a sign that says something like, 'This area is being streamed on the internet' to let people know this is going on and give them a chance to stay clear of the camera.

    Most of the science sessions are off limits too since the AAS considers them intellectual property, but we do have permission to stream a few events.

    For example, we have permission to live-stream the JWST Town Hall and JWST Science Sessions on Wednesday, along with any Hubble Science Sessions.  I'll post a schedule as soon as some things have been shored up and finalized.  Should be a lot of fun!

    So if you're interested in watching an experiment in public outreach in action, then bookmark this page and visit often.  If nothing live is going on at the time, then the last recorded stream will be shown. 

    Please give me feedback on what you think and offer any ideas and suggestion by commenting on the stream or sending me a tweet @DeepAstronomy.  This stream will also be available on our Facebook Page under the Ustream Live App.


    Live streaming video by Ustream

  • September 30, 2013

    Episode 5: The Horsehead Nebula in the Infrared

    by Tony Darnell

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    Shownotes

    The constellation of Orion is one of the most recognizable patterns in our night sky.  Within its boundaries lies the Orion Molecular Cloud Complex, located some 1,500 light years away.

    Inside this complex, on the farthest eastern edge of Orion's belt, is one of the most photographed nebulae in astronomy: The Horsehead Nebula.

    This nebula was first recorded in 1888 by Scottish astronomer Williamina Fleming at the Harvard College Observatory and ever since, we have been captivated by it.

    The red or pinkish glow originates from hydrogen gas predominantly behind the nebula, ionized by the nearby bright star Sigma Orionis, which is really a young, five-star system just out of view.

    The darkness of the Horsehead is caused mostly by thick dust, although the lower part of the Horsehead's neck casts a shadow to the left. Streams of gas leaving the nebula are funneled by a strong magnetic field. Bright spots in the Horsehead Nebula's base are young stars just beginning to form. 

    Since 1888, this has been our main view of the Horsehead Nebula and it has become an icon.

    But in April, 2013, astronomers using the Hubble Space Telescope released another view, one that only Hubble's infrared cameras in space could provide.

    Here is the Horsehead Nebula in the infrared.

    In the Hubble image, the backlit wisps along the Horsehead's upper ridge, illuminated by Sigma Orionis, can be seen.  Along the nebula's top ridge, two fledgling stars peek out from their now-exposed nurseries.

    This nebula gets its shape from powerful forces within this stellar cradle.  

    Harsh, ultraviolet radiation from one of these bright stars is slowly evaporating the nebula. Gas clouds surrounding the Horsehead have already dissipated, but the tip of the jutting pillar contains a slightly higher density of hydrogen and helium, laced with dust. This casts a shadow that protects material behind it from being stripped away, and a pillar structure forms.

    The Hubble Space Telescope has been providing us with ground-breaking science for two decades.  And every once in a while, it takes time out to give us a portrait of familiar friends in a completely new light.

    Keep Looking up.

  • June 20, 2013

    Episode 4: The Hubble Ultra Deep Field in 3D

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    Shownotes

    Astronomers, in 1996, attempted something extraordinary.  They pointed the Hubble Space Telescope into a part of the sky that seemed utterly empty, a patch devoid of any planets, stars and galaxies. This area was close to the Big Dipper, a very familiar constellation. The patch of sky was no bigger than a grain of sand held out at arms length.

    This was a somewhat risky move by the scientists. After all, observing time on this telescope is in very high demand, and some questioned whether it would be wasted trying to look at nothing. There was a real risk that the images returned would be as black as the space at which it was being pointed.

    Nevertheless, they opened the telescope and slowly, over the course of 10 full days, photons that had been travelling for over 13 billion years finally ended their journey on the detector of humanity's most powerful telescope, their feeble signal collected almost one by one.

    When the telescope was finally closed, the light from over 3,000 galaxies had covered the detector, producing one of the most profound and humbling images in all of human history--every single spot, smear, and dot was an entire galaxy, each one containing hundreds of billions of stars.

    Later, in 2004, they did it again, this time pointing the telescope toward an area near the constellation Orion. They opened the shutter for over 11 days and 400 complete orbits around the Earth. Detectors with increased sensitivity and filters that allowed more light through than ever before allowed over 10,000 galaxies to appear in what became known as the Ultra Deep Field, an image that represented the farthest we've ever seen into the universe.

    The photons from these galaxies left when the universe was only 500 million years old, and 13 billion years later, they end their long journey as a small blip on a telescope's CCD.

    These galaxies, while standing absolutely still, are racing away from us, in some cases faster than the speed of light.  The spacetime between us and everything else grows larger by the minute, pushing the galaxies in this image to a distance of over 47 billion light years. Because of universal expansion, the farther something is away from us, the more it's light is shifted toward the red and the faster it appears to be moving.  Edwin Hubble himself discovered this by measuring the redshift of many galaxies. Redshift is a measure of the amount of shift in a galaxy's spectrum toward the red and measures not only speed, but distance as well.

    Recently, Hubble scientists put the icing on the cake. Using the measured redshifts of all the galaxies inside the image, they made a 3D model of the Ultra Deep Field. This is how it looks when we apply the distances of the galaxies in the most important image ever taken.

    There are over 100 billion galaxies in the universe. Simply saying that number doesn't really mean much to us because it doesn't provide any context. Our brains have no way to accurately put that in any meaningful perspective.  When we look at this image, however, and think about the context of how it was made, and really understand what it means, we instantly gain the perspective and cannot help but be forever changed by it.

    We pointed the most powerful telescope ever built by human beings at absolutely nothing, for no other reason than because we were curious, and discovered that we occupy a very tiny place in the heavens.