Episode 4, August 5, 2020

Episode 4, August 5, 2020

Over The Solar System’s Horizon — The View of Stars Beyond Pluto @1:12
     
The New Horizons probe that visited Pluto a few years ago has now gone so far from Earth that some nearby stars have actually shifted positions in the sky, the first “alien” skies we have seen.  Dr. Tod Lauer of NOAO and the New Horizons team describes how they took photos of these ‘star shifts’ or parallaxes and what they tell us.

The Phoenix Stream — How the Death of a Globular Cluster Tells Us About the Birth of the Milky Way @25:49
     
The Milky Way galaxy has a surrounding halo of matter–stars, gas and other things–and threaded through it are star streams, the shredded rivers of stars made from destroyed satellite or dwarf galaxies and globular clusters, spheres of hundreds of thousands of stars once tightly packed into a few light years.  The massive gravitational tides of our galaxy rip them apart when these star groups  get pulled into us.  But one stellar river, the Phoenix Stream, has stars so deficient in atomic metals that it appears to come from a time before the Milky Way was formed.  The research of Carnegie Institute astronomers Alexander Ji, Ting Li, and University of Sydney grad student Zhan Wan reveals how the destruction of this globular starts to explain how the Milky Way was actually created.  And how halo streams may reveal clues about dark matter!

Skies Over Earth for August 6 thru 20  @1:06:09
     
Jupiter and Saturn dominate the evening sky, and point where Pluto and New Horizons would be. Venus lights up the dawn, and so does the waning moon which will curtail all but the brightest Perseid meteors.  Find Mars near the Moon on the 9th, when the Moon appears smallest in diameter, at its apogee.  Lots of Mars anniversaries this month, and Mars probes on its way.  When you look at Mars and the Moon this month, you are looking at the Earth’s path direction in space.

{Artwork–courtesy, Dr. Ting Li, S5Collab}

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