Gravity at the End of the Universe: October 28, 2013

Show notes for the 28th of October 2013

Hosts: Jesse, Paul, Rob B., Harrison
Title: Gravity at the end of the Universe

Return of the hosts! Harrison and Rob B. come out of retirement to help Jesse review the movie ‘Gravity,’ even though Paul had not seen it yet (SPOILER ALERT). Dream Chaser successfully completes its test by with a crash, while ATV-Einstein sets to burn up on reentry. The most distant galaxy yet has been discovered at a redshift greater than 7.5, or roughly 13 billion light years away. Thanks for listening! Podcast and show notes below.

This week in space/astronomy history:

1. October 23, 2001 – Named as a tribute to the vision and spirit of space exploration as embodied in the works of renowned science fiction author Arthur C. Clarke, the 2001 Mars Odyssey spacecraft entered Martian Orbit at 10:30 pm ET. Mars Odyssey is also the primary means of communications between Earth controllers and robotic missions on the surface of the planet – both MERs and Curiosity (Suggested Reading: NASA Mission Page).

2. October 24, 1946 – First photo of Earth from orbital altitude. Photo was taken with a 35mm camera atop a V2 rocket launched from New Mexico. See the image here.


1. The hosts of York Universe have all seen the movie ‘Gravity,’ and decided to review it!

2. Solar eclipse on Sunday, November 3. People from northern South America, across the U.S. Eastern Seaboard and up through the Canadian Maritimes will see a brief partial solar eclipse finishing up around 30 minutes after local sunrise. The brief annular “ring of fire” portion of the eclipse begins at sunrise just ~1,000 kilometres east of Jacksonville, Florida, as it races eastward across the Atlantic.  A “hybrid eclipse” that has not been seen since 2005 (Suggested Reading: Universe Today article).

3. Mission Accomplished in Dream Chaser Test, Despite Crash Landing: Flawless flight, fantastic data, left landing gear failed to deploy on landing. This flight is expected to allow the craft to clear a $15 million design hurdle. “The landing gear wasn’t part of this test.” (Suggested Reading: Space News article)

4. Comet Ison update. With perihelion now only 1 month away (November 28), Ison continues to brighten.  At 10th magnitude it remains a challenge to see but scientists continue to express optimism that the comet will survive perihelion and emerge into the pre-dawn sky with a perceptible tail for all to see. (Suggested Reading: Sky and Telescope article)

5. The Coldest Place in the Universe. ALMA has imaged the Boomerang Nebula in Centaurus, 5000 LY away. This object is a pre-planetary nebula, a star in it’s death throes, and the rapidly expanding gas has cooled it to only 1K, less than the CMB.  Previously thought to be lopsided or bowtie shaped, it is now seen to be roughly spherical when the CO molecules within are observed. (Suggested Reading: NRAO press release)

6. ATV-4 (Albert Einstein) undocked from ISS today. The crew sent down a funny tribute to Albert Einstein: . Re-entry is set for Saturday at 12:00.

Major Topics Discussed:

1. Most distant galaxy discovered yet, z=7.508
Redshift is a measure of the speed an object is moving away from us. Thanks to Edwin Hubble, there is a natural law that says relates distance to speed: the further something is from us, the faster it’s moving away from us. Therefore, we use the term ‘redshift’ to talk about distance.
It’s logarithmic, check out this graph to see how redshift relates to distance.
Starting from parent sample of 100 galaxies chosen to have redshifts greater than 7 based on their colour emission, 43 were observed spectroscopically at exposures times of roughly 5 hours. Of the 43 objets, only 8 showed any emission features, and only 1 showed emission that could be measured at greater than 5-sigma (to better than 1 in 1 million confidence).
This is a massive, bright, highly star forming galaxy existing just 700 million years (roughly) after the big bang. This indicates that: 1., stars/galaxies form quick, 2., they can be moderately chemically enriched (i.e., not Pop III stars), and 3., this galaxy may be the progenitor for some super massive galaxy. (Suggested Reading: Nature Article, arXiv preprint,)

Thanks for listening!
-YorkUniverse Team
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