Hosts: Pat, Julie, Paul
Title: King Marshall and the Galaxies of the Round Council
In tonights show following some nostalgic commentary on the origin of the word “telescope”, we quickly head for the realm of the galaxies, specifically our Local Volume and the galaxies within. Professor Marshall McCall takes us on a whirlwind trek of over 400 galaxies, some 35 very bright and close and 14 in the realm of a Local Sheet. These 14 seem to have influenced teh development of teh Milky Way and are affectionately referred to as teh Council of Giants. We finish the show with a quick update on NASA’s “twin experiment” to the ISS and touch on the closest exoplanet in size to the Earth: Kepler 186f.
This week in space and astronomy history:
1. April 14, 1611: the word “telescope” was first used in public. According to Alan Hirshfeld’s book “Parallax: The Race To Measure the Cosmos”, this milestone occurred at a banquet held in honour of Galileo by the pioneer scientific society, the Accademia dei Lincei (Academy of Lynxes). Galileo showed the guests the satellites of Jupiter, other celestial marvels, and an inscription on a building three miles away. The Greek mathematician Giovanni Demisiani coined the word telescopio (in Italian) from the Greek “teleskopos” or “far-seeing”, and one of the academia’s founders, Prince Federico Cesi, announced the name publicly to honor Galileo. Galileo himself had used the term “perspicillum”, a Latin term meaning “optical instrument” in general.
2. April 14, 1981: the first orbital test flight of (2 days) the space shuttle (Columbia) ended with a landing at California’s Edwards Air Force Base. The pilots included John Young (Gemini and 2 x Apollo (10 and 16)) and Robert Crippen.
3. April 24,1990 HST launched on Space Shuttle Discovery. HST mirror is 2.4 meters (7.9 feet) in diameter, which is small by modern standards; the real advantage of HST is that it is above the Earth’s atmosphere. Although the instruments need corrective lenses to compensate for the mirror’s flawed shape, HST is 24 years old and going strong!
Interview Guest: Marshall McCall interview: “Council of Giants”
Prof. Marshall McCall obtained his PhD at the University of Texas at Austin, then took up a postdoctoral position in Canberra Australia (Mt Stromlo), before joining the faculty at York University in 1988. Currently he is the Chair of the Department of Physics and Astronomy. His research interests include studies of structure, evolution and formation of galaxies and galaxy aggregates. He has just published a paper titled A Council of Giants, with an accompanying YouTube video (we’ve put the link in the online public viewing chatroom):
1. NASA twin experiment
Scott and Mark Kelly are both NASA astronauts, and they are also twins. In March 2015, Scott will begin a year-long stay on the ISS, while Mark who is retired will hang back on Earth. The brothers will be tested before, during and after Scott’s stay in space to see how extended space travel affects the human body. Ten proposals have been selected and aim to explore the twins’ genetics, biochemistry, vision, cognition and much more. This harkens to Einstein’s relativity thought experiment, the “twin paradox”, where one twin leaves in a high-speed rocket and returns to Earth younger than the one that was left behind. Unfortunately (or fortunately), the ISS doesn’t move fast enough to test this. Suggested reading: NASA Science article, Universe Today article
2. Earth-sized planet found in habitable zone NASA Ames,Science @ NASA, Bad Astronomy Article, Using NASA’s Kepler Space Telescope, astronomers have discovered the first Earth-size planet orbiting a star in its “habitable zone”. That’s the range of distance from a star where liquid water might pool on the surface of an orbiting planet. Other planets have previously been found in stars’ habitable zones, but until now they were all at least 40 percent larger than Earth. The new discovery, Kepler-186f, is more Earth-like: its radius is 1.1 times that of Earth’s, with an uncertainty of about 13 percent. That means it is almost certainly a rocky planet like Earth (although extrasolar planets have been nothing if not surprising). Its mass is not yet known, Kepler-186f is located about 500 light-years from Earth in the constellation Cygnus.
The system is also home to four companion planets (Kepler-186b, c, d and e), which orbit a star half the size and mass of our sun. It orbits a star in the constellation Cygnus classified as an M dwarf, or red dwarf, a class of stars that makes up over two-thirds of the stars in the Milky Way galaxy. 186f is located at the outer edge of teh Habitable Zone and receives about 50% the flux from its star compare to what Earth receives from our Sun.
3. Mars probably too cold for liquid water during most of its history Nature Article.
Research published today in Nature Geoscience suggests that liquid water has flooded the surface of Mars only during occasional warm spells, not during a prolonged period in the planet’s history. The reason is that Mars’ atmosphere was probably never thick enough to keep the temperature on Mars’ surface above freezing for long periods. The evidence comes from Mars’ impact craters. If Mars had a thick atmosphere, small objects would break up passing through it, rather than reaching the surface to create craters.
Using Mars Reconnaissance Orbiter images, Dr. Edwin Kite and colleagues cataloged more than 300 craters in a region near Mars’ equator where the surface is estimated to be 3.6 billion year old. They compared the size distribution of those craters to computer simulations of impact cratering results over a range of atmospheric densities, incoming projectile velocities, etc. The comparison suggests that the atmospheric pressure of old Mars was at most 150 times its current value, which is less than 1/3 what is thought to be needed to keep the surface temperature above freezing.
Water could have flowed on the surface when the atmosphere was temporarily thickened by volcanic outgassing or by release of gas by large impacts that vaporize any surface or subsurface ice in the impact region. A previous study suggests that a 200-kilometre-wide object hitting Mars would be enough to keep the planet above freezing for about a century.
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