THE SOUTHWORTH PLANETARIUM
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70 Falmouth Street   Portland, Maine 04103
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Altitude:  10 feet below sea level
Founded January 1970
Julian Date: 2459051.16
2019-2020:  CLXXXI


THE DAILY ASTRONOMER
Monday, July 20, 2020
Remote Planetarium 67: Week 14 Quiz


So, a few people have asked me:  what is the plan for the Remote
Planetarium?
Well, ordinarily, the DA school year begins in early September and ends on
the first Friday in August.   This year, as you well know, is certainly not
ordinary!   The Remote Planetarium will take a three week break starting
August 10th and then resume on August 31st, when the regular school year
begins.      The Remote Planetarium will continue as long as the
planetarium remains closed.   Therefore, we expect that the Remote
Planetarium On-Line Astronomy Course will continue through December 2021.
 According to current projections, the Southworth Planetarium will open for
the spring semester.  At that time, the Remote Planetarium will end and the
regular Daily Astronomer will resume.   Of course, this entire plan could
change.   Not much is certain at the moment.  Then again, except for
mathematical astronomy, is anything in life actually certain?

(Oh and, on request, I included a baby photo at the end of the quiz.)


*1.  Astronomers have found approximately _____________ exo-planets as of
mid-July.*
a.  2400
b. 3200
c.  4200
d. 11,300

*2. Name one of the two astronomers who received the Nobel Prize in Physics
for discovering the first exo-planet around an active star. *

*3.  What technique did they employ to find this planet?*
a.  The Radial Velocity Method
b. The Transit Method
c.  Transit Timing Variation
d.  Direct Observation.

*4.  Can the solar system barycenter ever be outside the Sun?*
a.  it was once possible.  However, the barycenter has remained within the
Sun for the last 100 million years
b.  yes.   The barycenter was last outside the Sun in 1167.
c.  yes.    The barycenter is outside the Sun right now.
d. absolutely not.  The barycenter has never been outside the Sun.

*5.  What is a main disadvantage of the radial velocity method?*
a.  it can only be used to find stars within one hundred light years of the
solar system
b. it can only be used to find highly massive planets
c.  it only works in infrared light
d.  there are no disadvantages to the radial velocity method

*6.  What does it mean when a planet "transits" a star?*
a.  the planet moves directly in front of the star
b. the planet moves directly behind the star
c.  the planet crashed into the star
d.  the planet escapes from the star's gravitational influence

*7.  In which year was the first exo-planet discovered through the use of
the transit method?*
a.  2002
b. 2003
c. 2004
d. 2006
e. 2010

[image: download.jpg]
*8.  The image above shows an idealized light curve for a transiting
planet.  What does the depth of the lower part of the curve reveal?*
a. the planet's period
b. the planet's size
c. the planet's temperature
d.  the planet's chemical composition

*9. The amount of time between successive transits yields information about
the planet's __________.*
a. mass
b. orbital period
c. chemical composition
d.  all of the above

*10.  Approximately how many planets have astronomers found through use of
the transit method so far?*
a. 1100
b. 1600
c. 2100
d. 2700

*11.  The Kepler Space Telescope is named after Johannes Kepler
(1571-1630).   He was responsible for the formulation of ____________.*
a. the Universal Law of Gravitation
b. the three planetary motion laws
c. the Law of the Conservation of Mass
d. the Theory of General Relativity

*12. The Kepler Space Telescope focused on stars around the constellation
______________.*
a.  Virgo the Maiden
b.  Sagittarius the Archer
c.   Cygnus the Swan
d.   Pegasus the Winged Horse

*13.  What is a disadvantage of the transit method of exo-planet detection?*
a.   it can only find planets around G and K type stars
b.  it can only find planets around stars within 300 parsecs of our solar
system
c.  only a small percentage of stars with planets will be aligned in such a
way as to allow us to observe the transit
d.  the transit method can't enable astronomers to find large planets

*14.   Based on Kepler's findings, astronomers estimate that our galaxy
might contain _______________potentially habitable planets.  (Earth sized
worlds within the habitable zones of their parent stars).*
a.  30 million
b. 80 million
c. 5 billion
d.  40 billion

*15.  How many planets within our own solar system are within the Sun's
habitable zone?*
a.   1   (Just Earth)
b.  2
c.  3
d. 4




ANSWERS

*1.  Astronomers have found approximately _____________ exo-planets as of
mid-July.*
c.  4200
As of July 14th, astronomers have detected 4282 exo-planets (3164 planetary
systems.)    As of July 19th, that number has increased to 4295.

*2. Name one of the two astronomers who received the Nobel Prize in Physics
for discovering the first exo-planet around an active star. *
Michel Mayor and Didier Queloz
In 1995, they discovered a planet about half as massive as Jupiter in orbit
around the star 51 Pegasi.   They received the 2019 Nobel Prize in Physics
for this discovery.

*3.  What technique did they employ to find this planet?*
a.  The Radial Velocity Method
Also called the "wobble method," the radial velocity method requires
observations of the star's spectrum to determine if the star moves back and
forth due to the gravitational influence of an orbiting planet.

*4.  Can the solar system barycenter ever be outside the Sun?*
c.  yes.    The barycenter is outside the Sun right now.
The barycenter is outside the Sun presently and has been since 2017.

*5.  What is a main disadvantage of the radial velocity method?*
b. it can only be used to find highly massive planets
Only highly massive planets can induce "wobbles" large enough for
astronomers to detect using this method.

*6.  What does it mean when a planet "transits" a star?*
a.  the planet moves directly in front of the star
When a planet transits a star, it moves directly in front of it from our
viewpoint.   During this transit, the star's apparent brightness diminishes
slightly

*7.  In which year was the first exo-planet discovered through the use of
the transit method?*
a.  2002
In 2002, the Polish astronomer Maciej Konacki and his team discovered
OGLE-TR-56b,
the first exo planet discovered through use of the transit method

*8.  The image above shows an idealized light curve for a transiting
planet.  What does the depth of the lower part of the curve reveal?*
b. the planet's size
The larger the planet, the greater the area it blocks and so the deeper the
curve.

*9. The amount of time between successive transits yields information about
the planet's __________.*
b. orbital period
The longer the orbital period, the greater the time that passes between
successive transits.

*10.  Approximately how many planets have astronomers found through use of
the transit method so far?*
d. 2700
Astronomers have found more exo-planets using the transit method than any
other single method.

*11.  The Kepler Space Telescope is named after Johannes Kepler
(1571-1630).   He was responsible for the formulation of ____________.*
b. the three planetary motion laws
*First law:*  Every planet's orbit is an ellipse with the Sun at one focus
*Second law:*  The radius vectors connecting the Sun and each of the
planets sweep out equal areas of space in equal intervals of time.  (or,
the closer a planet is to the Sun, the greater its orbital velocity)
*Third law:*  (The "Harmonic Law")   The square of a planet's period is
proportional to the cube of its semimajor axis (mean distance)

*12. The Kepler Space Telescope focused on stars around the constellation
______________.*
c.   Cygnus the Swan
The KST examined hundreds of thousands of stars within the Cygnus the Swan
region.    As impressive as that number might be, it represents a minuscule
fraction of all the stars comprising the Milky Way Galaxy.

*13.  What is a disadvantage of the transit method of exo-planet detection?*
c.  only a small percentage of stars with planets will be aligned in such a
way as to allow us to observe the transit
Fewer than one in a hundred planet systems are aligned with Earth so as to
enable us to observe the star's apparent brightness decrease as a result of
the planetary transit.

*14.   Based on Kepler's findings, astronomers estimate that our galaxy
might contain _______________potentially habitable planets.  (Earth sized
worlds within the habitable zones of their parent stars).*
d.  40 billion
If even 0.1% of these worlds actually harbors life, the galaxy would
contain 40 million life-bearing planets: a figure that staggers the
imagination!

*15.  How many planets within our own solar system are within the Sun's
habitable zone?*
c.  3
Venus, Earth and Mars are all technically within the Sun's habitable zone.
Being terrestrial planets (rocky with comparatively thin atmospheres), they
are also all "Earth-like."  However, both Venus and Mars are barren of life
as far as we can determine.    So, in regard to our solar system, only one
in three potentially habitable planets is actually life bearing.   Still an
impressive ratio!


[image: 2167_2.jpeg]

*Susan and our daughter Miranda.  *(Susan is on the left.)

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