Oct 20th: First Earth-Sized Planet in the Habitable Zone & A Unique Metal World: Asteroid Psyche

By on October 20, 2019 in
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Podcaster: Dr. Al Grauer

travelers-in-the-night

Title: Travelers in the Night Eps. 43 & 44 – First Earth-Sized Planet in the Habitable Zone & A Unique Metal World: Asteroid Psyche

Organization: Travelers in The Night

Link : Travelers in the Night ; @Nmcanopus

Organization: Travelers in The Night

Link : Travelers in the Night ; @Nmcanopus

Description: Today’s 2 topics:

  • The Kepler Space Craft has found tiny regular dips in light from a star which is about 500 light years away in the constellation of Cygnus. The dips in brightness come about when planets pass between their star and the Earth. This particular star has at least 5 planets. One of them is named Kepler-186f.
  • The asteroid Psyche is named for a Greek mythological figure. It  was discovered in 1852 as a moving point of light in the night sky. The size and mass of Psyche suggest that it is dense enough to consist largely of iron.

Bio: Dr. Al Grauer is currently an observing member of the Catalina Sky Survey Team at the University of Arizona.  This group has discovered nearly half of the Earth approaching objects known to exist. He received a PhD in Physics in 1971 and has been an observational Astronomer for 43 years. He retired as a University Professor after 39 years of interacting with students. He has conducted research projects using telescopes in Arizona, Chile, Australia, Hawaii, Louisiana, and Georgia with funding from NSF and NASA.

He is noted as Co-discoverer of comet P/2010 TO20 Linear-Grauer, Discoverer of comet C/2009 U5 Grauer and has asteroid 18871 Grauer named for him.

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Transcript:

31E43 – First Earth-Sized Planet in the Habitable Zone

The Kepler Space Craft has found tiny regular dips in light from a star which is about 500 light years away in the constellation of Cygnus. The dips in brightness come about when planets pass between their star and the Earth. This particular star has at least 5 planets. One of them is named Kepler-186f. It is similar to the Earth in size and is located at a distance from its star which may allow life as we know it to exist.
This newly discovered cousin to our Earth orbits a M dwarf star which is very much cooler than our Sun. Its year is only 130 days long.

Suppose that the temperature and atmospheric conditions on this newly discovered Earth like planet are conducive to the development of human like creatures. Can we imagine what they might look like?

A hint as to how difficult this might be comes from the fact that on Earth our eyes have a structure which is tuned to be most sensitive to the light emitted by our Sun. Beings which have developed on a planet orbiting an M dwarf star will have eyes of unfamiliar size and shape since their star puts out a pattern of radiation which is very different from our Sun.

Another variable is the mass and thus the force of gravity on a planet’s surface. Beings on a planet with either more or less gravity than Earth would be likely to have sizes and shapes which are hard to imagine.

In the future NASA missions like the Transiting Exoplanet Survey Satellite and the James Webb Space Telescope will discover and measure properties of nearby Earth like planets. If any of them harbor life may be hard to determine.

32E – 44 – A Unique Metal World: Asteroid Psyche

The asteroid Psyche is named for a Greek mythological figure. It  was discovered in 1852 as a moving point of light in the night sky.  This small world is about 155 miles in diameter and orbits the Sun between Mars and Jupiter every 5 years. 

The mass of an asteroid can be determined in principle, by how its gravity effects other objects which it encounters.  An asteroid’s size can be determined by how it dims a star as it passes between the star and us. The size and mass of Psyche suggest that it is dense enough to consist largely of iron. This hypothesis is supported by radar observations. These data suggest that the asteroid Psyche may be the core of what was once a rocky proto planet which lost its outer layers during catastrophic collisions in the early solar system. 

The iron world Psyche is unique among the many millions of asteroids in our Solar System which are composed of some combination rocks and ice.

Dr. Elkins-Tanton and her colleagues propose that NASA send a robotic space craft to orbit the asteroid Psyche for 6 months. During that time it would take images, measure magnetic fields, and make an accurate mass determination. 

The Earth’s core and magnetic field effects our weather and climate. However, we can’t travel to the center of the Earth.  Instead we must rely on earthquake waves to know anything about what is at our planet’s core.  A visit to Psyche would allow us to directly study a naked planet’s core and provide clues as to the nature of what is beneath our feet. 

For Travelers in the Night this is Dr. Al Grauer

End of podcast:

365 Days of Astronomy
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